CHAPTER 1
INTRODUCTION
Obesity reflects the excessive accumulation of fats in bodies. The abnormal accumulation of fats poses various health dangers to people. The dangers include being at a greater risk of suffering from various health conditions such as obesity. Trasande and Chatterjee (2009) observed that obesity posed health risks which predisposed victims to incurring high medical costs in addition to other direct and indirect costs.
The body mass index (BMI) is the most commonly used measure for obesity. BMI is obtained by dividing the weight (Kilograms) by height squared (Meters). A person whose BMI is 25 or more is considered is to be overweight. An individual who has a BMI of thirty or more is considered obese. Overweight and obesity present serious health risks for several chronic illnesses such as diabetes, cancer and cardiovascular ailments. Previously, obesity was considered a problem that affected only high-income people. However, trends have shifted as obesity now affects even low-income people.
Key facts based on the WHO (2013) on obesity are as follows. Since the 1980’s, obesity has almost doubled. In the year 2008, over 1.4 billion adults were overweight. Of these people, over 200 million men and 300 million women were obese. In the same year, thirty-five percent of the adults were overweight while eleven percent were obese. It should also be noted that 65% of the global population reside in countries where obesity and overweight kill. Matters became worse in 2011 as more than forty million children (under the age of 5) were overweight. On an annual basis, childhood obesity costs were roughly 14.3 billion US dollars (Trasande & Chatterjee, 2009).
Despite the negative statistics, obesity is preventable. In the United States, the rates of obesity have continued to rise, as is the case across other parts of the world. In light of the above revelations, this dissertation seeks to examine the relationship between 100% fruit juice and the obesity problem in the United States. In order to achieve the goal, the NHANES data of 1999-2004 is sampled. The primary hypothesis is that the consumption of 100% fruit juice reduces the risk of becoming obese or overweight.
The table below shows the rates across the United States.
2010 State Obesity Rates
State % State % State % State %
Alabama 32.2 Illinois 28.2 Montana 23.0 Rhode Island 25.5
Alaska 24.5 Indiana 29.6 Nebraska 26.9 South Carolina 31.5
Arizona 24.3 Iowa 28.4 Nevada 22.4 South Dakota 27.3
Arkansas 30.1 Kansas 29.4 New Hampshire 25.0 Tennessee 30.8
California 24.0 Kentucky 31.3 New Jersey 23.8 Texas 31.0
Colorado 21.0 Louisiana 31.0 New Mexico 25.1 Utah 22.5
Connecticut 22.5 Maine 26.8 New York 23.9 Vermont 23.2
Delaware 28.0 Maryland 27.1 North Carolina 27.8 Virginia 26.0
District of Columbia 22.2 Massachusetts 23.0 North Dakota 27.2 Washington 25.5
Florida 26.6 Michigan 30.9 Ohio 29.2 West Virginia 32.5
Georgia 29.6 Minnesota 24.8 Oklahoma 30.4 Wisconsin 26.3
Hawaii 22.7 Mississippi 34.0 Oregon 26.8 Wyoming 2
Table courtesy of Centers for Disease Control and Prevention. The above table demonstrates the obesity rates in various States (updated 2012).
The main cause of overweight and obesity is an imbalance in energy which occurs due to a mismatch on the calories consumed and those expended (WHO, 2013). Put differently, when more energy is consumed than the amount used, obesity and overweight problems are likely to emerge. As the WHO observed, there has been an increase in the intake of energy-dense foodstuffs which contain a high amount of fats. Moreover, the research has confirmed that the consumption of sweetened fruits has a positive correlation with the increase in incidences of obesity (DiMeglio & Mattes, 2000). In addition, there has been decrease in physical activity as people now embrace a sedentary lifestyle.
The consumption of sugar-sweetened drinks has continued to increase (Popkin, 2010). The statistics become grimmer as the average American consumes approximately forty-five gallons of sweetened drinks per year (Andreyeva, Chaloupka & Brownell, 2011). Since the consumption of sweetened drinks is associated with high incidences of obesity, the trends of unhealthy living are likely to continue. The high incidence of obesity has been linked with the consumption of sugar-sweetened drinks (Woodward-Lopez, Kao & Ritchie, 2011). The liquid calories do not induce a similar sensation as solid foods do. Hence, the calories are likely to add on to those that are already consumed as opposed to replacing them. Babey et al. (2009) established that adults who drank soda daily were twenty-seven percent more likely to become obese, regardless of their income, race or ethnicity. In regards to children, the risk was up to sixty percent. Hence, the consumption of soft drinks shows a tendency to increase the risk of becoming obese and overweight.
Fruit Juice and Obesity
Fresh juice is counted among the natural power foods. Fruit juice has an important role in terms of its contribution towards healthy living (Franke et al., 2005). It is observable that fruits are rich in nutrients, minerals and vitamins. Based on what fruit juices comprise, they strengthen the bodies’ powers to fight accumulated toxins. The fruits have concentrated natural sugar which is critical in bringing out vital energy.
Natural juice is an ideal source of minerals and vitamins. These substances are helpful in activating both enzymes and co-enzymes (Franke et al., 2005). In the absence of such activation, body enzymes would not be able to perform their duties as expected. The enzymes are responsible for several body functions such as digestion and absorption of food, which would become difficult if the body lacks the minerals and vitamins. Similarly, the enzymes play a significant role in the transformation of the minerals and vitamins into the body tissues.
Due to such benefits, consuming fruit juices is commendable as opposed to the preference for sweetened drinks, which give false energy. Another important attribute is that fruit juice energy is often in the form of fructose (Ghanim et al., 2010). The process of transforming fructose to glucose does not require much energy from the body. Consequently, fruit juice energy is a critical source of real energy to the body.
The alarming statistics regarding the consumption of sweetened drinks has played a key role in influencing the lifestyle choices that people are making. Specifically, society is now embracing a healthier lifestyle than it did previously. This follows the realization that fresh fruit juice offers a better alternative to sweetened drinks (Feldman, 2001). It has been alleged that 100% natural juice is more nutritious because it is nutrient-dense. The nutrients include vitamin C, potassium, folate, in addition to other natural plant compounds which promote healthy living (Feldman, 2001).
Based on previous research, consuming fruit juice has advantages and disadvantages. Consuming the juice during the morning hours relieves bodies from the need to invest heavily in food digestion (Ghanim et al., 2010). Consuming natural fruit juice is also associated with weight reduction (Ghanim et al., 2010). The consumption of natural fruit juice allows the body to focus on other aspects such as weight reduction since the burden of digestion is reduced.
Both the USDA 2010 Dietary Guidelines and the American Academy of Pediatrics noted that fresh juice was far more nutritious as well as beneficial to human health. As the 2010 Dietary Guidelines indicated, 100% fruit juice accompanied by low fat milk offered a nutrient dense beverage which has a significant amount of nutrients, in addition to containing minimal calories. However, the 2010 Dietary Guidelines underscored the need to consume various foods moderately in order to obtain maximum health benefits.
The American Academy of Pediatrics suggested that serving four to six ounces of fresh juice to children in a day among children between the ages of 1-6 and twelve ounces to those aged between seven and eighteen could be helpful. Furthermore, the consumption of fruit juice has been closely associated with a positive influence on both diet and nutrition. Focusing on the data by the National Health and Nutrition Examination Surveys (NHANES) of 2003-06, adolescents and children who consumed fresh juice enjoyed a more nutritious diet in comparison to non-fruit juice consumers (O’Neil et al., 2012). The primary reason was that fruit juice consumers had a higher intake of significant nutrients such as magnesium, folate, calcium, phosphate, potassium and vitamins A and C. The recommendation by the American Academy of Pediatrics, coupled with the findings of the O’Neil et al. (2012) study on the National Health and Nutrition Examination Surveys, support the notion that fruit juice consumption improves health.
Another NHANES study indicated that adults who consumed the 100% orange juice showed a tendency to have as lower BMI, body fat, and waist circumferences in comparison to those who never drank juice (Chun et al., 2011). Another notable finding from the NHANES study was that adolescents and children who consumed 100% orange juice stood a better chance of complying with the My Pyramid health recommendations which calls for limiting sugary and flavored foods (Sebastian, Enns, Goldman, Bowman, Moshfegh, 2011).
It is tentatively conclusive that the consumption of fruit juice is healthy since the studies by Chun et al. (2011), Sebastian, et al. (2011) and O’Neil et al. (2012) based on the NHANES data, concluded that consumers of 100% fruit juice had lower BMI, body fat and waist circumference.
Dietary Guidelines
Findings from past research showed that consuming fruit juice regularly is associated with a reduced exposure to chronic illnesses (Trasande & Chatterjee, 2009). Fruit juice offers fibers and other critical nutrients to the body leading to healthy living. The fact that Nutrition and Your Health: Dietary Guidelines for Americans are published every five years manifests the significance of leading a healthy lifestyle. The inclusion of fruit and vegetable juice among the recommended dietary intake augments the view that they are significant components of healthy living.
In practice, any food or dietary guidelines are developed with the intention of helping consumers select the most appropriate foods for a healthy living. The guidelines achieve that goal by providing quantitative value, which each person should meet. A food guideline gives details on recommended nutrient intake. Put differently, the guideline is particularly useful in the provision of a conceptual framework that assists in selecting the right amounts of food.
Focusing on the USDA Food Guide Pyramid is significant towards understanding how food should be consumed. The pyramid divided food into five main categories (grains, fruits, vegetables, protein-rich foods and dairy). The grid provides quantities that should be consumed from each group, as well as the limits which cannot be exceeded. The measures are often given to reflect daily requirements.
The guidelines acknowledge the fact that the consumption requirements of different age groups or sexes differ. In addition, the drafters of the dietary guidelines appreciate the notion that physical engagements in terms of exercises influence the level/amount of food that should be consumed.
Fruit juice should be served twice to four times on a daily basis, based on the Food Guide Pyramid recommendations. Individuals who require a lesser amount of calories should consume a smaller amount of fruit juice while those with higher demands should consume more of the juice. Apart from the crucial information conveyed regarding fruit consumption, the guidelines also give information about every other food. Thus, the guidelines are of great value not only to nutritionists but also to consumers.
Group Age Amount
Toddlers 2 – 3 1 cup
Girls 4 – 8 1 cup
Boys 4 – 8 1.5 cups
Girls 9 – 18 1.5 cups
Boys 9 – 13 1.5 cups
Boys 14 – 18 2 cups
Women 19 – 30 2 cups
Men 19 + 2 cups
The information is from, Nutrition Fact Sheet, www.fruitjuicefacts.org
The above intake of fruit juice applies to individuals who exercise for 30 minutes or less. Those who engage in more physical activities should consume larger amounts. Based on the above statistics, males are required to consume more fruit juice than females.
Recommended Daily Amount Age Group
None Below 6 months
4 – 6 ounces 1 – 6 years
8 – 12 ounces 7 – 18 years
Source – American Academy of Pediatrics
The recommendation to consume fruit juices is based on the idea that they have a high nutritional value to the health of consumers. Various fruit juices have different nutrients, an aspect that improves their relevancy to the health requirements of consumers. Such nutrients/minerals include folate and vitamins which are highly helpful to human health.
Problem Statement
Obesity and overweight have become an increasing concern across the world. The obesity rates affect both sexes as well as all ages of the population. American society is greatly affected by this problem. The obesity problem seems to affect African American females more than other subgroups (Ogden et al., 2006). Overweight and obesity deny people, especially children, the opportunity to enjoy a quality lifestyle. Young people suffering from obesity or from being overweight have to deal with teasing from colleagues, low self-esteem, and bullying, among other concerns. Similarly, adults who are obese or overweight encounter the risk of suffering from insulin resistance, diabetes (type 2), metabolic syndrome, etc. Despite the perceived presence of ethnic or racial variations, obesity/overweight has a tendency to track. As Janssen, et al. (2005) observed, childhood obesity or overweight could be a precursor for other diseases later in life. Thus, the obesity problem predisposes victims to incurring more healthcare costs, as established by Finkelstein, Ruhm and Kosa (2005). With the above realization, the need to probe obesity or being overweight as a problem is significant.
In the recent past, the obesity epidemic has taken a toll on American society. Since the 1970’s, the obesity rates have nearly doubled in the United States (Flegal, Carroll, Ogden et al., 2010). It is also alleged that more than 65% of the American population is overweight. It should be noted that the determinants and consequences of the epidemic are complex and are practically beyond the purview of the current study.
Obesity and overweight pose serious implications on the United States. Various studies have considered the economic impact of the epidemic in the United States (Finkelstein, Ruhm & Kosa, 2005). Economic costs identified have included direct medical costs, human capital costs, productivity costs and transportation costs (Trasande & Chatterjee, 2009). Of the four main costs of obesity, the direct medical costs are the most alarming. Trasande & Chatterjee (2009) indicated that obesity has been associated with several other illnesses such as high blood pressure, asthma, arthritis, etc. Therefore, diagnoses of these conditions demand further treatment costs. In order to understand the direct medical costs attributable to obesity, it is necessary to focus on the incidence of conditions associated with this problem.
Thompson et al. (1999) considered a model relating BMI and risks of five conditions associated with obesity. The conditions included: hypercholesterolemia, hypertension, CHD, type 2 diabetes and stroke. The dynamic model captures the direct and indirect impact of obesity on health. It should be noted that obesity is a risk factor for the said conditions. The rise in the incidence of exposure to risk is also associated with an increase in healthcare costs.
Thus, it emerges that obesity-related conditions have a cost element as patients must pay for diagnoses and treatment. A number of studies have estimated the costs using case studies, representative surveys, cohort studies, etc. (Thompson et al., 1999). Moreover, there is a widespread acceptance in the literature that obesity-related health conditions force people to incur substantial costs.
There are several factors that influence the emergence of obesity or overweight problems. Such factors as racial, ethnic, diet patterns and physical activity play an influential role in the occurrence of the problem. Dennison, Rockwell and Baker (1997) indicated that the consumers of 100% fruit juice were at a bigger risk to become overweight and to be obese than non-consumers were. Nevertheless, more studies on the subject have offered conflicting results. The likelihood that there is an association between obesity/overweight and the consumption of 100% fruit juice continues to elicit divided opinions (Baker, 2007). In light of the controversy surrounding the relationship between the consumption of 100% fruit juice and obesity/overweight and the negative effects associated with obesity and overweight, conducting a study to ascertain the connection between the two variables is significant. Unhealthy conditions such as obesity and other related conditions predispose victims to higher costs in seeking healthcare. The overall effect is that huge resources are spent on health matters. This investigation intends to use the National Health and Nutrition Examination Study (NHANES) survey data to examine the relationship between 100% fruit juice and the obesity problem in the United States.
Dietary Guidelines and Statistics
Based on the above graph, the trend shows that the consumption of fruit beverages has continued to rise over the years. A rise in the consumption of fruit juice has been studied widely in reference to its association with obesity and overweight.
Similarly, the above graph confirms that the consumption of fruit juices has risen. Thus, assessing their effect on health is critical.
Based on the Food Guide Pyramid recommendations, fruit juice should be served twice to four times on a daily basis. However, the guidelines discourage individuals who require a lesser amount of calories from consuming higher amounts of fruit juice. Besides, the guidelines also give information about other foods. For example, the guidelines recommend higher fruit juice intake among individuals who exercise more. The same guidelines indicated that males are required to consume more fruit juice than females.
CHAPTER 2
LONGITUDINAL DATA
A dataset is longitudinal when it tracks a specific type of information on known subjects at given points at a time (Carlson et al., 2001). For instance, a part of such data could contain specific people and their standardized measures (could include weight, height, age, etc.).
Longitudinal data can be used to remedy shortcomings of cross-sectional data driven researches. It is notable that cross-sectional research designs rely on the nature of research questions (Carlson et al., 2001). When studying the relationship between the consumption of 100% fruit juice, obesity and healthcare costs, it is critical to determine an approach that shades more light on such a relationship. Thus, the question is whether the researcher seeks to compare the relationship at one point to another, or over a long period of time. When one is interested in establishing the relationship at one point, the use of the cross-sectional approach is preferred. On the other hand, when considering the relationship of variables at different points, the focus should be on the longitudinal approach to data collection and analysis.
Cross-sectional data is observation-based (Carlson et al., 2001). Hence, researchers record observations about the study subjects without having to interfere or manipulate the environment. Thus, in a study focusing on the association among 100% fruit juice, obesity and medical costs, the focus would be on those people consuming the juice, as opposed to non-consumers. The main strength of this type of research design is that it can compare various groups at a given point in time. However, cross-sectional data may not offer definitive information on cause and effect associations (Carlson et al., 2001). This is because such studies do not consider the pre- and post- conditions surrounding the research subjects. Thus, in assessing the relationship between fruit consumption and obesity, it is not possible to know the weight levels of the people being studied before the research.
The main benefit of using longitudinal data lies in its ability to measure change over time (Carlson et al., 2001). This allows for estimating the effect of different factors on a given issue/variable. The overall effect of a variable on another can also be estimated. Moreover, longitudinal data covers the past, in addition to present data. This facilitates the evaluation of the effects of a specific policy on an issue. Longitudinal data also allows for the usage of analytical strategies to measure or to assess the influence of various factors on given variables.
NHANES Data
The National Health and Nutrition Examination Survey (NHANES), which is a program of studies assessing both health and nutritional status of people from American society is used for the study. The program offers unique data as it combines physical examinations, as well as interviews of participants. The NHANES works under the National Center for Health Statistics (NCHS). The NCHS is a part of the Centers for Disease Control and Prevention (CDC) charged with the responsibility of providing significant information/data on health in the United States.
The program was introduced in the 1960’s, and from that time, it has been carried out as a chain of surveys that focus on various groups of the population, as well as health topics. The survey adopted a continuous approach as it changed its focus to meet emerging health and nutritional measurement demands. Each year, the survey picks a sample of about five thousand respondents using the random approach. The respondents are selected from states across the United States. Of the chosen states, researchers from the program visit respondents in fifteen states each year.
The program interview encompasses dietary, socioeconomic, demographic and other health related issues. The examined components include dental, physiological and medical measurements, in addition to laboratory tests. The survey findings are then used to estimate the prevalence of major conditions/diseases and risk factors for the various diseases. The information is often used to assess the nutritional condition and its relationship with disease prevention or health promotion. Primarily, the NHANES data form the basis upon which the state’s national recommendations, measurements and standards are set.
Determining the Dietary Intake Data
The NHANES Dietary data are collected by employing twenty-four hour dietary recalls. To achieve the goal, the use of automated multiple-pass methods is employed (Moshfegh et al., 2008, Blanton, Moshfegh, Baer & Kretsch, 2006). The approach involves two recalls. A trained interviewer conducts the first recall while the use of a telephone is employed to conduct a follow-up recall after three to ten days. Upon such an exercise, only the data that was deemed appropriate by the National Center for Health Statistics staff is included to guarantee reliability and validity of findings. Further, in-depth descriptions on dietary recalls as well as data collection are sought from the Dietary Interview Training Manual of the NHANES (National Center for Health Statistics, 2003).
In the previous studies, 100% fruit juice was defined as per the expectations of the United States Food and Drug Administration guide which held that 100% fruit juice is a juice that has no other substance apart from the fruit concentrate and added nutrients. The individual codes of fruits as per the guidelines of the NHANES 2005-2006 are used to gauge the intake of fruit juice. On the other hand, the consumers are defined as individuals taking part in the consumption of 100% fruit juice during the recall period. In a bid to determine the intake of nutrients, the third version of the USDA Food and Database for Dietary Studies is used. The nutrients examined include dietary fiber, macronutrients, sodium, vitamins A, B6, C, magnesium, potassium and folate. The intake from supplements is also considered depending on the objectives of a study.
Under the NHANES studies, examining physiological measures has remained relevant. Waist circumference, height and weight were obtained based on the NHANES procedures. The body mass index is calculated using kilograms (Kg) divided by the height (meters squared), then squared. In calculating the odds ratio, obesity/overweight and the weight circumference, the National Lung and Blood Institute guidelines play a significant role (National Institutes of Health, 2012).
The determination of the systolic and diastolic blood pressure is done by employing the NHANES procedural guidelines. The average values of these scores are then used. The overall level of cholesterol and the density (high) of lipoprotein cholesterol are determined by an examination of no-fasted individuals. On the other hand, it has been necessary to determine aspects such as low-level lipoprotein cholesterol, blood glucose, triacylglycerides and insulin. Still, fasted subjects are used to determine these values.
Another critical aspect is metabolic syndrome. This syndrome is viewed alongside the NHLBI criterion which considers three factors. They include consuming anti-hypertensive drugs or hypertension and abdominal obesity, taking anti-hyperlipidemic medications or consuming hypoglycemic substances.
When focusing on NHANES study, the Healthy Eating Index (HEI-2005) and Food Group Equivalent Consumption have been applied. Previously, the food group equivalent consumption was known as the My Pyramid Equivalents. They were determined basing on the application of figures from the database of My Pyramid Equivalents. Whenever deemed necessary, the intakes as determined by the NHANES 2005-2006 will be matched to related foods. The HEI has been used to aid in the determination of the quality of the diet consumed. The use of the SAS code to determine the HEI scores has also been preferred. The code is obtained from the Center for Nutrition Policy Promotion.
Studies relying on the NHANES data have used various statistical analyses. The sampling weights, the sampling units and group information as detailed by the NHANES have been included in many analyses. This is done using the SUDAAN V10.0 by the Research Triangle Institute. To determine the usual consumption, the use of SAS V 9.2 has been adopted. The determination of the usual levels is a representation of the long-term mean scores on daily intakes, which are computed by the removal of excessive intra-personal differences in the consumption levels. These are better estimates since dietary intakes are supposed to be met over a longer period rather than being taken at a day. The normal consumption of 100% juice and chosen nutrients are calculated based on the National Cancer Institute method (Usual Dietary Intakes, 2010).
For the usual intake of 100% fruit juice, taken episodically, the NCI model (2 part) has been applied. On the part of the nutrients, the one part model is applied. The Distrib v1.1 and Mixtran v1.1 from the NCI SAS macros is used to generate the parameter effects upon the adjustments of the covariates and the estimation of the distribution of the usual consumption. The latter is done using the Monte Carlo simulation method (Usual Dietary Intakes, 2010). The covariates of the study are the day of the 24 hour recall, having a weekday code (Monday-Thursday) or weekend code, (Friday-Sunday) and the sequence of the dietary recalls (1st or 2nd). The software developed by the NCI is used to obtain the estimates of the variance. In order to obtain the variance estimates, the one-day sampling measures of fruit consumption are used. The use of balanced repeated replication to obtain the standard errors is also employed. The same method is expected to yield confidence intervals. In constructing the balanced repeated replication, the Fay adjustment factor is used. Another significant measure used is the Dietary Reference Intake which is helpful in presenting the usual intake of each nutrient under investigation.
The determination of significance in the differences among 100& fruit juice consumers and non-consumers, the use of a Z-statistic is considered. Linear regressions are also used to reflect the differences among categories of consumers in regards to physiological attributes. Further, the application of logistic regression is critical in determining the odds ratio of becoming overweight or facing other health concerns. The covariates of the linear regression have included ethnicity, gender, age, physical activity engagement, body weight, BMI and poverty index ratio. Physical activity engagement is determined by using a questionnaire.
In order to confirm or disconfirm literature findings, studies have often reviewed data from the NHANES. The studies incorporate two scales that have been used previously by other researchers. The two scales, The Healthy Eating Index (HEI-2005) and food group equivalent intake are appropriate in this kind of study. The level of appropriateness is high since the instruments have been used. Thus, validity and reliability are assumed to be relatively high.
For the purposes of the proposed study, demographic factors (pregnancy status, ethnicity, gender and age), BMI, and weight will be considered. Based on the NHANES of 2004-5, I will refer to a demographic file in order to obtain the age, gender, pregnancy status and ethnicity of the respondents. Similarly, in conducting the body measurement exercise, I will use the Body Measurement file to record the weight measures of the study respondents. The same measure is expected to offer the height and body mass index.
Pseudo Panel Research
The need to use a pseudo-panel base has received theoretical substantiation from the various scholars. The most important theoretical postulates of the pseudo panel research findings have been recognized by the co-joint study of Trasande and Chatterjee (2009). Moreover, it has been empirically inferred that the practical dietary strategies applications supported by the use of pseudo panel research findings are 3% more effective than the ones utilized without this approach ( Skinner et al, 1999). Its need has been practically recognized in the co-joint study of Allison, Zanolli and Narayan (1999) and in the fundamental study of Babey (2009).
Theoretically, the need to undertake this type of research is dictated by the practical necessity to model the situations ( Ballew et. al, 2000). In many instances, panel data is difficult to find. However, a series of cross-sectional data exist. For example, the NHANES data is an example of cross-sectional data in the US which gives details on variables bordering on nutrition. The research is concerned with tracking cohorts using the NHANES data. A cohort is a group that has fixed membership; hence it is possible to trace patterns of individuals. When dealing with large cohorts or samples, it is possible to generate time series data which is useful in interpreting behavioral associations among cohorts or for the whole sample in the same way when using pane data. The procedures employed in constructing the cohorts and estimation are considered below.
Economic associations are assumed to be linear in parameters although not in data. The parameters may contain individual effects. Averaged versions of similar forms for the cohorts exist, corresponding to the individual associations although with unobservable data locations/points. For instance, whenever there is a fixed additive individual effect, there is a corresponding added cohort fixed effect to the cohort population. Sample cohorts from averages based on the survey are sometimes error-prone estimates of the unobserved cohort population averages. Because micro data is used to come up with the averages. Ideally, they should also be used to develop variance estimates and sample covariance means. Therefore, it is possible to estimate the population relationships consistently.
Model and Data
The data to be used consists of T independent cross-sections occurring at different periods. Each of the cross-sections is a random sample representing some population. Individuals from different points cannot be the same. The conventional literature requires the indexing of variables using a double subscript. The z stands for the cross-section while i(t), 1…, Tz indexes the subjects in cross-section t. The model is as shown below
Yi(t), z=α Yi(t), t-1 + x’i(t), tβ +∑i(t), t, t=1, …, T; i(t) =1, …., Tz, (1)
In the above model, the k dimensional vector xi(z), t may include a time-invariant, time-varying variables and intercept. Yi(z), z-1 refers to the y value at z-1 for an individual observation in the t cross-section. The z is however unobserved in the available data. It is assumed that the error term has the following features.
E {∑i(t), txi(t), t} = 0, t =1, …., T (2)
Since the lagged values for z are unobserved for any individual, an estimate is constructed using information on y values of individuals observed at z-1. In doing so, fi(t) stands for a group of time on invariant variables such as an intercept term. The orthogonal projection in the cross section t of
E* {Yi(t), t│ zi(t)} = zi(t) αt, t = 1, …, T (3)
E* stands for the orthogonal projection of a given t. The reduced form is estimated consistently for Nt≥∞ by regressing
Yi(t), t on zi(t)} to give αt-1, (4)
αt-1 is estimated using the data from different individuals who are not indexed by i(t). The population is defined as Y*i(t), t-1 = zi(t) αt-1zi(t) and is presumed as dummy variable vectors which correspond to mutual cohorts. After this, predicted values are inserted into the original model.
Yi(t), t =Αyi(t), t-1 + x’i(t), tβ + E*i(t), t, t =1,…., T; I(t) = 1,… Nt, (5)
Where
E*i(t), t = Ei(t), t +α{Yi(t), t-1 – yi(t), ti-1} (6)
yi(t), ti-1 is included to take care of the errors in measurement. Although asymptomatic in nature, the error will be uncorrelated to the predicted value.
The assumption that
E { {∑i(t), tzi(t)} = 0, t =1,…, T (7)
holds.
Methodological Concerns/Limitations
To gauge the relationship between 100% fruit juice and being overweight, it is necessary to assess the nature of evidence and strength. Determining the strength of evidence is done through the assessment of the quantity, quality and consistency of previous studies. Generally, the quality shows the level to which study aspects. Such as the design and execution, reduce both systematic and non-systematic bias. Further, the analysis should minimize bias. Subject selection should also be objective.
Quantity reflects the number of studies and the sample size or power. The attribute also encompasses the magnitude or size of influence. On the other hand, consistency shows the level at which studies establish similar or related results regardless of the approaches employed.
Studies based on longitudinal data are sometimes limited. For instance, the studies rely on data collected at two points in time. Although some researchers believe that studies based on such data are more informative as they permit a better speculation of causal links, questions remain. This is because, in practice, the data only offer temporal trends, as opposed to showing causal links.
As of 2008, studies on the topic either used longitudinal or cross sectional data to assess the association between weight gain and the consumption of100% fruit juice. In practice, longitudinal studies, which are conducted as per the standards of research, should offer stronger evidence on any association between the variables. However, it is remarkable that each study has strengths, as well as weaknesses.
Assessing overweight or weight gain is an arduous task. This view is held in reference to the notion that weight gain is a function of many factors. Such factors as age, race, socio-economic status, sex, etc. are influential factors on weight status. Thus, in epidemiological studies focusing on the relationship between diet and weight gain, there is a need to identify and apply covariates in an appropriate manner. For instance, age and sex/gender highly influence weight status. Thus, it is common to add a covariate of the two variables, although they lack a clear biological significance in terms of the high level of interaction. Other potential covariates include food security at the household level, parental, and physical activity. Ethnicity or race is also influential on weight status. Thus, it is an important covariate that is included since there is a possibility of encountering systematic variations in diet reporting (Flegal et al., 1988). Moreover, there are absolute variations in intakes, weight or adiposity (Freedman et al., 2006). The relevance of these covariates apply to the need to determine appropriate covariates in a study. This is significant since some covariates may be inappropriate in given studies. The best approach involves pretesting the covariates in order to understand which ones are significant in statistical terms.
Nearly all nutrition-based studies employ a questionable approach in data collection. This is because the studies depend on the self-assessment of participants. The reliance on self-assessments may compromise the accuracy of the measures. Evidence from cross sectional data-based research has shown that a positive relationship between the consumption of 100% fruit juice and weight status is limited. One of the few studies that have focused on cross sectional data is the study by Dennison, Rockwell and Baker (1999). In the study, the researchers compared the consumption data using NHANES data. The limitation of the study was that it had overlapping populations (Dennison, Rockwell, Nichols & Jenkins, 1999). The effect of overlapping populations is on the possible prejudice that interpretations would make regarding the association between variables. Other cross-sectional data based studies have relied on responses from self assessors (Dennison, Rockwell and Baker 1999 and Dennison, Rockwell,, Nichols & Jenkins, 1999). Dennison, Rockwell and Baker (1999) established that children who consumed over 12 ounces of 100% fruit juice showed an increase in their BMI. They were also at a higher risk of becoming obese than those who consumed lesser amounts.
Other studies did not find a relationship between the consumption of fruit juices and weight status or obesity. Among the studies were those of Nicklas, O’Neil & Kleinman, 2007 and O’Neil, Nicklas & Kleinman, 2007. These studies used NHANES data in assessing the relationship. The studies relied on well-established protocols while sampling.
Addressing this issue, theoreticians strongly admonish researchers to conduct longitudinal and cross-sectional studies. The relevance of these approaches to evaluate such phenomenon has been recognized by the academic research community, state authorities and practitioners. The need to provide theoretical substantiation of the practical findings is done in order to increase academic soundness and verification of the study in question (Deaton et. al, 1985)
Longitudinal studies are also helpful in understanding the most suitable approach to conducting studies. In the studies (Skinner et al., 1999; Skinner & Carruth, 2001), none found any association between 100% fruit juice consumption and weight status.
Like a cross-sectional study design, a longitudinal one is also observational (Carlson et al., 2001). The researcher does not interfere with the study environments. However, in the longitudinal study, a researcher carries out a number of observations on subjects for some period of time. The main strength of the longitudinal studies is that they facilitate the detection of changes in the features of the studied subjects. By extending observations beyond a single moment in time, a sequence of events is established. This allows researchers to account for weight levels at the start and the end of a study. In this regard, the longitudinal study is better placed to establish a cause-effect relationship. Based on this evaluation, the longitudinal approach is proposed in order to overcome weaknesses associated with cross-sectional studies.
Basics of Econometric Juice Consumption and Obesity Studies
The contemporary scholarly experience indicates that a multitude research methods, grouped into the cross-sectional and longitudinal studies. While the efficacy of the both techniques have been classified as highly effective in terms of examination specific medical-oriented phenomenon, the practice indicates that only a combination of such technique and an integral holistic approach can lead to totally viable and positive academic findings, that can be utilized to construct practical guidelines in order to eradicate a specific negative phenomenon (Faith et. al, 2006).
For the needs of this very study (the correlation between fruit juice consumption, obesity and overweight among different age categories in the United States of America) a threefold approach will be followed, entailing the holistic use of cross-sectional and longitudinal study elements.
The role of pseudo-panels is immense for the needs of this survey. Under this type of econometric approach, the specific phenomenon is observed within intervals during a specific timeframe, while the number of the tested group is not accentuated. The studies delimitating the different weight-fruit consumption ratios across different states of the United States have been taken as a working model.
The findings of pseudo-panel investigation have been duly corroborated by the respective findings of panel research, similarly conducted on a number of the states in the United States. In this type of data analysis, the accent has been on the observation of a specific scholarly phenomenon on a permanent basis. Under the fundamentals of the hypothesis of this paper, the medical intervention of the dietitians and obesity healthcare practitioners has not been considered.
Cohorts studies in this paper are focused on the two types of available medical and academic research. The first type is linked to the examination of obese people and their juice consumption during a specific period of time. The second type of research involves the examination of weight-healthy people and their fruit juice consumption.
Pseudo-Panel Studies
One of the most fundamental studies conducted in this regard has been performed co-jointly by professor Bolton and his associates, Heaton and Burroughs in 1981. The examination period involved the analysis of 84 obesity patients registered in New York City hospital during a three year period, 1978 to 1981. The evaluation materials included medical transcripts and testimonies obtained from the medical practitioners and from the patients themselves. The evaluation of the results took place on a quarterly basis.
Mathematically, the model followed by the research team could be presented in the form of the following logarithmic equation
where a stands for health vacillations of the targeted obesity and overweight groups, and b represents the average regular fruit intake consumed by them. The margins and possible errors of the study (4-5%) have been considered as well.
During the first interview, the patients and their attending physicians reported that the average weekly intake of juice ranged from 10 to 12 liters of US Jews manufactured with the use of traditional technologies. Before the survey was started, the weights of the tested group exceeded the standards of the World Health Organization by 14% – 40%. The targeted group was apprised about the particular repercussions to which excessive fruit consumption may lead. The treatment process was conducted on the basis of the available traditional obesity tackling techniques. However, after the consultation with the academics performing the research and their medical attending observers, 23 patients decided to diminish their fruit juice intake, while the remaining 61 participants continued to consume fruit juice on a regular basis (when the research was initiated the fruit and fruit juice intake was not included in the obligatory diet programs prescribed by the doctors).
The first quarterly examination revealed that no significant changes took place, except for the aggregate weight decrease anticipated in advance by the medical practitioners. However, the 23 patients who agreed to cease fruit juice consumption were admonished to refrain from consuming fruit juice further. The second quarterly examination indicated that the average weight decrease of the second (those, who abstained from taking fruit juice) was 1-2% larger than among those who continued to practice regular consumption of fruit juices. It should be noted as well that for the needs of that study, the practitioners did not distinguish the types and the industrial make of fruit juices the patients consumed. After a third quarterly examination was conducted, it was revealed that the weight discrepancies included 3-4% between the two groups. After the sixth quarterly examination, the research indicated that in aggregate the average weight of the second evaluation group was 10-12% smaller than the first one. However, the later examination revealed no significant weight vacillations, and the progression remained invariant. Hereby, following the findings of this study it can be assumed that juice intake can be considered as a determinant on the short-term basis.
The second targeted pseudo panel study conducted by professor Tam and his associates (2006) was focused on the evaluation of the same patterns among school students in Australia. A total of 200 students attending clinical departments in Sydney and Canberra were tested respectively. While regular medication measures were consumed by them, the focus was on fruit and fruit juice consumption by the study participants. The control period encompassed two years and the respective examinations were conducted on a semiannual basis. Additional factors, such as differences and similarities of the diets prescribed by the dietitians were not taken into consideration and the study was limited to fruit intake exclusively. All the respondents consumed juice on a regular basis, with average fruit consumption being 10-13 liters of juice (irrespective of the manufacturing type and fruit type) per week. During the targeted period, fruit juice intake was not diminished, while other dietary procedures were followed.
The working model of the study can be presented in the following way:
Overall, the semiannual findings indicated that the obesity rates of the examined group diminished as prescribed and promised by their respective dietary analysts. Therefore, it was concluded that fruit intake does not inhibit conventional dietary methods that included the removal of fat intake and increased sport activities. However, 5 students, after additional consultations with independent dietary specialists, resolved to diminish fruit and fruit juices intake. The third semiannual evaluation evinced that their progress were 12%-15% bigger than among the main analyzed group. Therefore, it can be inferentially concluded that refraining from excessive fruit juice and fruit consumption can beneficially contribute weight-fighting campaigns.
Panel Studies
One of the most illustrative studies on this subject was performed by Lin and Morrison (2002), who examined fruit juice consumption and increased body mass of the parsed targeted overweight group. The study was conducted in the Clinical Research Institute (State of Texas). The examination involved 96 people, middle age category, who had entered the first phase of obesity. The representatives of the analyzed group were registered at the clinical department with different complaints, varying from cardiovascular diseases to bone-related complaints. The average weekly diet included 10-15 liters of apple, orange and other juices (the manufacturing method was not taken into consideration). The examinations were done during 3 consecutive years on an annual basis. While no weight-tackling methods were intentionally taken by the targeted group, during the 1st year of examination, 68% of the analyzed targeted group entered the second phase of obesity. Considering that the evaluation of the patients whose fruit and fruit juice consumption was smaller did not enter the second obesity stage during the same time period, it can be inferred that fruit juice consumption remains one of the most determinative factors that generate obesity trends among patients.
The co-joint study of Tohil, Seymour, Serdula, Kettel-Khan and Rolls (2004) examined the same situation in the state of New York, on the basis of an Internet-distributed questionnaire. In this study, 500 respondents were independently tested and the causation between fruit juice consumption and overweight-obesity was evaluated. In accordance with the statements submitted by the respondents, 321 of them consumed more than 13 liters of orange and other juices weekly, while the rest consumed less than this amount. The evaluation of the results took place during one year and the individual examination of the results took place every other month. The data collected by analysts indicated that the average weight of the targeted group was increased to 4-6%, while the weight of those who abstained from excessive juice intake due to the peculiarities of their lifestyle remained either in the normal range of weight or reported the increase in weight insignificantly (1-2%).
Cohort Studies
The most illustrative cohort study was conducted by the team under control of Professor Flood and his associates (2002). The research was conducted on the basis of San-Diego National Breast Cancer Research Center and involved the examination of 150 patients suffering from overweight. The study was linked to 3 years term and the examination of the patients took place on a semi-annual regular basis. The first group of patients (34 persons) reported that their average fruit juice intake was lower than 10 liters of fruit juice per week (the manufacturing peculiarities were not taken into consideration and the type of the juice consumed was disregarded as well). Within the first year of examination, the study indicated that average weight accumulation among the first targeted group (those, who consume more than 10 liters of juice weekly) was 10% bigger than among those who replaced juice intake with water or other sugar-free beverages. The ultimate findings revealed that the aggregate average weight of the targeted group was 14% larger than among those 34 who abstained from fruit juice intake. It is necessary to highlight in the course of this paper that the lifestyle of the analyzed targeted groups was similar and the only variables that have been tested included fruit juice consumption and the corresponding weight changes of the targeted groups.
The work conducted under the leadership of professor He and his affiliates in (2004) evinced the causation between fruit consumption among middle-aged women. While the rest of the analyzed studies analyzed the compound general public of the adults, in this research the gender peculiarities of the specific gender group have been accentuated. The evaluation of 50 45-60 years old women consuming more than 10 liters of apple juice on a weekly basis indicated that at the moment the analysis was commenced all the respondents suffered from overweigh or obesity proportionally (29% to 71% respectively). The fruits and fruit juice deliberate consumption was the variable and the bodily mass index was the invariable of the mathematical equation employed by the research team. The one year evaluation period indicated that the body weight increase among the analyzed group constituted average annual rise in 1-3% individually. Considering that the rest of the factors that can hypothetically affect weight increase were considered by the research team, it can be empirically inferred that fruit juice consumption can be considered one of the most important determinants that leads to weight increase.
The Assumptions
Based on the findings of the statistics, the scholars assume that and increase in juice consumption indeed leads to increase in weight. While the role of other factors is considered, the scholars were firmly convinced that the effect should also be analyzed in an isolated way, i.e., the situation when a human is not subjected to any other weight-increasing factors but the sole effect is exercised by the juice consumption. Moreover, it is considered that for people of younger ages, especially for children 3-14 years old and adolescents, the effect is considerably intensified due to the age’s biological peculiarities. In particular, it is stated that although the metabolism and growth processes are increased more than in the body of an adult, the interior energy interchange is diminished. Therefore, the weight increase is among the most anticipated outcomes of the process.
The Scope of the Problem
This part of the paper outlines the relevance of this study, with the focus made on the statistical evaluation of the obesity rates and obesity-related process growth in the United States of America. The second part of the chapter provides statistical information relating to juice consumption of the targeted geographical region.
Obesity has taken on epidemic scales in the United States of America. The following to test sticks provided by National Health and Nutrition Examination Survey provide the obesity ranking of the United States for the period between the 2010 and 2011 research years in accordance with the obesity criterion elaborated by the World Health Organization (Orden, et. al, 2008).
State and District Obesity Adults Overweight Obesity Children Place (US States)
State of Colorado 21.0% 55.0% 9.9% 51
Hawaii 20.7% 55.3% 13.3% 50
Connecticut 20.8% 58.7% 12.3% 49
Massachusetts 20.9% 56.8% 13.6% 48
Vermont 21.1% 56.9% 11.3% 47
Rhode Island 21.4% 60.4% 11.9% 46
Montana 21.7% 59.6% 11.1% 45
Utah 21.8% 56.4% 8.5% 44
District of Columbia 22.1% 55.0% 14.8% 43
New Jersey 22.9% 60.5% 13.7% 42
California 23.1% 59.4% 13.2% 41
Arizona 23.3% 59.5% 12.2% 40
Florida 23.3% 60.8% 14.4% 39
New Mexico 23.3% 60.3% 16.8% 38
New York 23.5% 60.0% 15.3% 37
Nevada 23.6% 61.8% 12.4% 36
New Hampshire 23.6% 60.8% 12.9% 35
Maine 23.7% 60.8% 12.7% 34
Wyoming 24.0% 61.7% 8.7% 33
Washington 24.5% 60.7% 10.8% 32
Idaho 24.6% 61.4% 10.1% 31
Minnesota 24.8% 61.9% 10.1% 30
Oregon 25.0% 60.8% 14.1% 29
Maryland 25.2% 61.5% 13.3% 28
Virginia 25.2% 61.6% 13.8% 27
Illinois 25.3% 61.8% 15.8% 26
Wisconsin 25.5% 62.4% 13.5% 25
Pennsylvania 25.7% 61.9% 13.3% 24
Kansas 25.8% 62.3% 14.0% 23
Delaware 25.9% 63.9% 22.8% 22
North Dakota 25.9% 64.5% 12.1% 21
South Dakota 26.1% 64.2% 12.1% 20
Iowa 26.3% 63.4% 12.5% 19
Nebraska 26.5% 63.9% 11.9% 18
Ohio 26.9% 63.3% 14.2% 17
State and District Obesity Adults Overweight Obesity Children Place (US States)
North Carolina 27.1% 63.4% 19.3% 16
Texas 27.2% 64.1% 19.1% 15
Alaska 27.3% 64.5% 11.1% 14
Missouri 27.4% 63.3% 15.6% 13
Georgia 27.5% 63.3% 16.4% 12
Indiana 27.5% 62.8% 15.6% 11
Michigan 27.7% 63.9% 14.5% 10
Arkansas 28.1% 64.7% 16.4% 9
Oklahoma 28.1% 64.2% 15.4% 8
Kentucky 28.4% 66.8% 20.6% 7
Tennessee 29.0% 65.0% 20.0% 6
South Carolina 29.2% 65.1% 18.9% 5
Louisiana 29.5% 64.2% 17.2% 4
Alabama 30.1% 65.4% 16.7% 3
West Virginia 30.6% 66.8% 20.9% 2
Mississippi 34.4% 67.4% 17.8% 1
It is evident that almost all states in the U.S. have fully exceeded the limit that is acceptable under the standards of the World Health Organization and popular scholarly opinion.
This chart composed by the National Health and Nutrition Examination Survey provides actual data for the international analysis of the obesity increase worldwide (Wang, 2008).
This map clearly indicates that the United States of America occupies the dominant place in the obesity increase internationally. Not a single country exceeds the United States in terms of obesity index increase.
This bar chart has been composed as a result of the research team working under the aegis of the World Health Organization (WHO, 2008 report). The aim of the study was to find out the percentage of people suffering from obesity and overweight in the English speaking countries (excluding the countries of the British Commonwealth).
The analysis of this graph suggests that the United States of America remains the unchallenged leader of the international obesity rally.
The following geographical chart denotes how the problem is distributed on the local, U.S. Level, i.e., the leadership in obesity trends domestically is found out (Wang et. al, 2008).
The map clearly manifests that obesity and overweight problems have a strong foothold in the United States of America. All states of the country are experiencing the gravity of the problem, irrespective of the fact that there have been multiple obesity and overweight eradicating initiatives launched by the respective health care agencies on both federal and local levels.
Fruit Juice Consumption Statistics
Scholarly concerns were raised relating to the causation between fruit consumption and increased obesity rates in the National Health and Nutrition Examination Survey. The most problematic issue in this context is to establish a connection between the consumer groups who say purchasing juice is the dominant or partially dominant beverage for their daily food ration and those who suffer from obesity and overweight. However, considering the fact that the vast majority (71%) of the population of the United States consume juices on a regular basis, it can be reasonably and logically assumed that various types of juices constitute the main beverage for the majority of Americans.
The following graph demonstrates fruit juice consumption (liters per capita) in the United States of America for the period between 2000 and 2010 (Weinraub, 2010).
The line clearly demonstrates that the juice consumption figures in the United States of America vacillate between 100 and 120 liters per capita. In accordance with the recommendations of the World Health Organization, an average adult human being (20-45 years old) is recommended to consume no more than 80 liters per year. Moreover, the predominant source for supplying the body with water is to be pure potable water, containing the normal set of minerals, vitamins and other ingredients.
Another important fact that shall be taken into consideration in this paradigm is the chemical structure of the juices being imported, produced and consumed in different countries. In accordance with the report of the World Health organization, there are various methods of juice production. Respective national legislation defines the criterion that is to be followed by the manufacturers to produce the juice. As far as the United States of America is concerned, the brief algorithm can be classified as concentration, followed by reconstitution. The last stages of the manufacturing process are the pasteurization and packaging of the juice products. The portion of the squeezed pure juice under this manufacturing method remains insignificant. Therefore, the positive influence of biologically friendly substances is minimized, while the presence of the ones that exercise negative effect is artificially increased.
Rationale
Scholars share the unanimous opinion that the factors that make juices obesity-generating aspect are the increased content of dietary fiber elements, while the energy density remains comparatively minimized, in contrast to other obesity-related determinants. Most importantly, the presence of viscous dietary fiber indicates that the sense of hunger is considerably minimized after the juice is consumed. Prospectively, excessive fruit consumption can lead to energy deficit and as a result to an increase in body weight.
Moreover, when the fruits are industrially processed, their water content is drastically diminished. The addition of sugar into the components hereby incrementally increases the energy density of the ultimate product. Although chemists speaking on behalf of the juice producing companies vigorously advocate the notion that sugar-free juices are becoming available at the market, taste and savor replacers exercise the same biological effect as the sugar-containing components do.
Another significant issue to be addressed here is the presence of additional satiety feeling produced by the juice intake. A multiple set of studies indicated that plasma-containing forms of foodstuff (i.e. beverages) contain more calories and, therefore, they are more energy-rich than similar substances produced in the form of puree. The main sugar-containing element in fruit is fructose, metabolism of which is slower while it has been industrially processed. Following this rule, scholars assume that the glucose rise is produced more slowly by the cells of a human being after a portion of juice has been ingested.
The Issue of Glycemic Production
The medical community actively reports that glycemic production capacities of a human being are considerably slower among the people who consume fruit as their main foodstuff than those who prefer a combined diet consisting of different food elements. The issue is that of paramount practical importance due to the fact that there is a direct causation between the discussed index and the satiety index of an average human being. The hormonal vacillations of a human being are among the most determinative issues that define the way the body responds to the intakes of glycemic-based chemical substances present in the juices. It has been empirically established that fruit juices containing high rates of glycemic-based chemical substances produce an appetite-diminishing effect but in the long run an average human being increases its food intake due to the fact that gradually the appetite intensifies. Moreover, the study conducted by the National Health and Nutrition Survey indicate that glucose-containing substances can be closely linked to the regulation of satiety on a short-term level. However, another popular opinion is that this rule is applicable to healthy, able-bodied human beings exclusively and cannot be applied with the same efficiency to the people who suffer from obesity or overweight issues.
Juice Intake, Obesity and Cohort Studies
The causation among obesity, overweight and fruit juice consumption has been established by many scholars. In accordance with the popular cohort method, two groups of participants were chosen for the experiment. The first group was exposed to the influence of specific experimental substances, while the second one totally abstained from intake of such elements. The majority of such studies processed by scholars are related to the United States of America. The targeted scholarly researchers have stipulated that there is inverse causation between fruit juice consumption and the body weight increase of the targeted respondents. More importantly, a number of studies conducted under the aegis of NHANES precisely indicated that children from low income families are more predisposed to gain extra weight while consuming fruit and fruit juice than their peers from middle income and well-off families. The common scholarly opinion in this regard is that the ration of children from middle and well-off families is relatively balanced and supplemented with respective portions of meat and cooked cereals, while the low-income kids do not have such opportunities.
The targeted study of the United States’ children fully backed up the assumption of the United States Medicine Institute to diminish consumption of fruit and fruit juice as the main preventive and treatment measure to reduce their imminent or present overweight or obesity symptoms. However, similar studies conducted in Australia have identified specific age peculiarities. In particular, it was found that before a child reaches the age of 5 years old, practically no weight-increase effect is exercised by fruit juices, irrespective of fruit composition (Allison, Zannolli, Narayan, 1999). The criterion for the research has been formulated on the basis of relevant international experience. To be more exact, it included the children who were not genetically predisposed to overweight and obesity and kept a generally normal lifecycle. The targeted group involved equal representation of children with Afro-America, Hispanic and White Protestant origin, in order to remove the genetic predisposition factor. In other words, whatever the internal chemical structure and the manufacturing process of the fruit followed, the increased metabolism processes of a young human being effectively copes with the ingestion processes.
Similar studies conducted in the Federative Republic of Germany indicated that girls of 5 years old and older are considerably more vulnerable to spirit dancing the negative effects of juice intake than our boys of that age.
Cohort Studies of Adults
Multiple numbers of cohort studies aimed at establishing the causation between the juice and fruit juice intake and the obesity and overweigh tendencies among adults have been conducted.
The fundamental study conducted by Skinner and his associates (1999) was aimed to evaluate the impact between fruit juice intake and the obesity and overweight physical deviations among the 20-45 years old targeted patients residing in the state of New York and not predisposed to overweight and obesity genetically. All of the targeted respondents (200) were attendants of the Bronx-Lebanon Hospital. The study indicated that daily consumption of juice resulted in the general body weight increase on 1-3%. Another important criterion that shall be mentioned here is that the targeted group was not taking fat-containing products, since all the respondents was on a dietary programs prescribed by their physicians.
Another important cohort study was done by Woodward-Lopez and his research group in 2011. The study was made on the basis of the randomly distributed questionnaires. The criterions involved the age of the respondents (25-40), their lifecycle particularities, gender (the representation of the males and females was equal) and absence of genetic overweight predisposition. The most important criterion of the study was the regular orange juice consumption (at least 6 liters per week). The study indicated that for the vast majority of the targeted group (76%) the annual weight growth constituted 1-3%.
On the basis of the outlined cohort studies, the conclusion that there is a direct causation between the weight increase and the consumption of fruit juice has been established.
Intervention Research and Cross Sectional Studies Confirming the Assumption
One of the landmark intervention studies examining the ration between the juice ingestion and the effect on weight increase has been conducted in state of Alabama, the USA, in 2008. Three groups of targeted adults (20-45 years old) were chosen to measure the effect of fruit intake into their body weight increase. No other chemical substances were present in their ration, and the targeted groups did not possess any weight-affecting peculiarities (i.e. neither one was a professional sportsman nor his / her life cycle included heavy physical exercising that condition fast and intensified burning of calories).
The issue of intervention research is the supervision over the targeted experimental group who continue to live their normal life cycle, and no changes in their dietary preferences are made (Chun et al, 2011a). The second targeted group is asked to make appropriate changes to their daily ration and to increase the intake of fresh fruits.
Several cross-sectional studies have been promoted by NHANES in order to measure the causation between the fresh juice and fruit consumption on the basis of the United States clinical units. The study involved the supervision over the two targeted groups undergoing post-treatment medical procedures in San Diego clinical department of the United States of America’s Healthcare Office. The first group was mandated to supplement their diet with fruit and fresh juice, while the second group was asked to reduce the amount of fat-containing products like steaks, fried potatoes and hams. The clinical studies indicated that for the short period the weight of the third targeted group remained unchanged, with slight increase in the weight mass of those who were genetically predisposed to weight increase ( whose parents were either overweight or obese people). For the second group taking juices and fruit and simultaneously diminishing the intake of fat-containing products, the results indicated insignificant negative weight vacillations (i.e., weight decrease) (Blum, Jacobsen and Donnelly, 2005). However, practically it was not possible to find out the major driving factor causing weight decrease since hypothetically it can be juice consumption and fat-ingestion reduction. However, analyzing the results of the first observed group, the most verisimilar hypothesis is that the reduction should be attributed to fat-containing product ration reduction.
The USA’s medical practitioners, in close cooperation with the scholarly community, have identified 23 studies meeting the requested criterion of targeted groups eligibility and long-term character (Boato et. al, 2002). After the feedback of the studies were evaluated and respectively analyzed, their results were classified into three categories: the first one was for the children of pre-school and elementary school age; the second group involved children from secondary school and adolescents, and the third one represented the adults. The total number of respondents was equal to 4 000 persons, with the biggest representation of the adults (accordingly, 2000 and 1000 for the children of each group). The gathered results indicated different findings for the different groups of people in the experiment. While the average bodily mass among the children and adolescents taking juices were generally increased, the one of the adolescents remained almost unchanged. However, specific individuals implicated in the study reported slight bodily weight reduction. The results did not differ drastically from the rest of the examined group. Therefore, the assumption that the consumption of fruit juices and fresh fruit are the most determinative factors that leads to weight increase of an individual since the cumulative effect of all the factors acting together is still to be evaluated (Dennison et. al, 1999).
The Opinion of Dietary Consultants
With regard to the opinion provided by the professional dietitians and nutritionists, it shall be stipulated that they are almost unanimous in their concern that proper weight-reduction strategy should be focused on the reduction of fresh fruit and fruit juice intake reduction. However, these strategies are caused primarily by the need to reduce the calories, content of which in the fruit and juices is very high as supported by previous studies.
The Analysis
Overall, the provided data suggests that juice intake by any age group inevitably contributes to weight increase processes of the targeted examined groups. However, as far as individual impact is concerned, it is still highly disputed by the scholarly community that the consumption of juice is a major determinant that regulates the weight of a human being although a strong causation is evident. The analyzed data clearly demonstrates the discrepancies in individual weight peculiarities between the targeted groups who consume juice as a main beverage and those who give their preference to potable water and other beverages with low sugar content.
CHAPTER 3
LITERATURE REVIEW
Literature on the topic of fruit juice consumption and obesity is overwhelming in terms of availability and diversity. In the following section, literature on the topic is analyzed with a view to determining patterns. The literature is divided into seven subsections. In the introductory part, studies of cutting across methodologies are presented while the remaining six phases focus on the following areas: obesity and costs, orange juice and fruit juice contribution to obesity, Body Mass Index (BMI) research, NHANES research and Pseudo-Panel research.
Despite the absence of fruit juice consumption and weight status, the obesity epidemic in the United States has been dominating public debate for a long time now. It should be remarked that macronutrients play a significant role in the emergence of health conditions such as obesity. However, the complexity of nutrients, coupled with the high level of processing involved, add difficulties to gauging the contribution of each nutrient to the emergence of health conditions. Several studies of scholars, among them Bray, Nielsen, Popkin (2004) and Ismail, Tanzer, Dingle (1997), considered how various food contribute to increase in the incidence of obesity and other chronic conditions. However, fewer studies have paid attention to the issue of a possible link between the consumption of 100% fruit juice and obesity.
Ogden and Carroll (2006) established that in America 1 out of 6 children was obese or at a risk of becoming overweight. In practice overweight children are at a bigger risk of becoming overweight in their adult lives. Overall, 100% fruit juice is highly nutritious as well as beneficial to healthy living. The USDA’s 2010 Dietary Guidelines for Americans recommended the juices for consumption when in need of substituting whole fruit. However, the US Department of Agriculture found that a bigger percentage of the population consumed less than fifty percent of the recommended levels.
The Juice Products Association supported the juice industry in endorsing the Academy of Pediatrics’ (AAP) recommendations regarding the maximum daily consumption of 100% fruit juice among children. The AAP advised that children between the age of one and six should consume four to six ounces of natural juice and 12 ounces for those between the age of 7 and 18.
During the transition time from liquid to solid food, 100% fruit juice is among the top three sources of carbohydrates (Skinner, Ziegler & Ponza, 2004). Approximately one out of five infants consumes fruit juice before they turn six months old (Briefel et al., 2004). The consumption of 100% fresh juice and fruit-flavored drinks could contribute towards building of excess energy. In such an event, there is a possibility of displacing nutrient-dense food in the diets of children. This realization supports the position that the role of fruit juice in becoming overweight is controversial.
100% fruit juice differs from sweetened juices in terms of fructose corn syrup concentration. Whereas the sweetened drinks have a higher concentration, 100% fruit juice has no concentration of the substance. 100% fruit juice contains minerals and nutrients including antioxidants. Studies focused on children have shown that consumers of 100% juice depict that they also come closer to observing dietary guidelines compared to those who do not consume any juice. Nevertheless, it is critical to observe that obesity is influenced by other factors such as overall lifestyles. Hence, it is not easy to determine how influential one factor such as the consumption of 100% fruit juice could be.
Nicklas, O’Neil & Kleinman (2010) investigated the link between the consumption of fresh juice and nutrient intake and weight status. These scholars employed a cross-sectional design in collecting data from adolescents in the age bracket of 12-18. In total, they reviewed the data relating to 3939 subjects. The participants were recruited from the National Health and Nutrition Examination Survey 1999-2002. The study employed the Logistic Regression and Least Square Means in analyzing the data. After generating the data it was adjusted for ethnicity, age, gender and energy intake. Upon this, the analyses were correlated with reference to a p value of .0125.
According to the Nicklas, O’Neil & Kleinman (2010) study 28% of the adolescents (only 51% of males, 42% of Hispanics, 29% of non-Hispanic black and 25% of non -Hispanic white) consumed fresh juice on the day of the appointment. On average, the amount of fresh juice consumed was 2.2% of total energy intake. When these consumers of 100% fresh juice were compared to non-drinkers, the latter category was found to be at a higher risk of consuming higher amounts of fatty and saturated fats than consumers. As research established, those who consumed more 100% fresh juice were also less likely to consume food with added sugar than the non-drinkers. However, the research did not find any connection between weight gain or loss and the consumption of fresh juice.
However, based on the findings, the research concluded that adolescents who consumed 100% fresh juice showed a lower tendency to develop increased weight. It was also established that fresh juice offered critical nutrients. In addition, the research held that a higher consumption of fresh juice was associated with a reduced consumption of discretionary fat, saturated fatty acids, total fat, as well as added sugar. Moreover, the higher consumption of fresh juice was not related to a decline in the consumption of meat, milk or grains.
The consumption of 100% fruit juice has been linked to higher levels of intake of such nutrients as vitamins B-6 and C, folate, magnesium and thiamin and overall improved health. Concerns about the connection between consuming juice and obesity have also been witnessed. Many studies focused on the relationship between weight gain and fruit juice consumption among children (O’Neil & Nicklas, 2008). The studies did not find a relationship between the two variables. Studies focusing on adults led to the establishment of an inverse association between the consumption of fruit juice and BMI (Pereira & Fulgoni, 2004). Similarly, other studies found an association between the consumption of obesity and the consumption of fruit juice (Pereira & Fulgoni, 2004). In contrast, a study by the Nurses’ Health Study found that fruit juice consumption was positively related to weight status (Schulze et al., 2004).
Fewer studies have focused their attention on the association between specific fruit juice and health. It should be recognized that in the United States, orange juice is the most consumed juice (United States Department of Agriculture, 2012). Irrespective of type, orange juice is among the most nutrient dense fruit juices (Rampersaud, 2007).
The often touted maxim that the consumption of soft drinks contributes to an upsurge in the rates of obesity in the United States has led to conducting studies to ascertain the authenticity of such assertions. For instance, O’Neil et al. (2012) conducted a study with the objective of assessing whether the consumption of 100% fruit juice was connected to weight gain. The primary aim of the study was to assess the beverage consumption among pre-school children who took part in the National Health and Nutrition Examination Survey 1999-2002 with a view to investigate the relationship between the beverages-intake and the weight status among pre-school children.
O’Neil et al. (2012) conducted a secondary analysis of the National Health and Nutrition Examination Survey (1999-2002 ) data. The study recruited 1572 children between the ages of two and five. However, only 1160 children were used in the final analysis. Based on the sample statistics, approximately 50% (579) of children were males. Based on demographics, 35% were White, 28.3% were Black while 36.7% of children were of Hispanic origin. In the sample 24% of the children were almost obese or at risk of becoming overweight since their BMI was greater than 85%. However, approximately 11% were obese as their BMI was over 95%.
On the basis of the findings, the differences between the BMI of the girls and boys were statistically insignificant. The same case applied to the differences in ethnicities. Another key finding was that the older (3.8yrs>) children tended to be overweight more than the younger ones. The study also established that 83% of the children consumed milk, 48% took 100% fruit juice, 44% consumed fruit drinks, while 39% took soda. Only 46.5% of the respondents consumed whole milk. Of the milk drinking category, roughly 5% consumed skim milk.
On average, the pre-school children took beverages amounting to 27oz./day. Milk accounted for 12.3 oz., 4.7 oz. reflected fruit juice intake, 5 oz. were consumed as fruit drinks while soda accounted for 3.25 oz. As per the results, the status of the weight was not related with the total amount of beverages taken. Further, the research indicated that there was an absence of a clinically significant relationship between milk types and weight status. The results also showed an absence of a statistically significant connection between 100% fruit juice and weight status. In conclusion, pre-school children consumed approximately 6 oz. less of 100% fruit juice based on the recommendations of USDA Dietary Guidelines and the American Academy.
Another study concentrated on investigating the link between the consumption of 100% fruit juice and three aspects: weight, nutrient intake and food group consumption (Ogden & Carroll, 2006). The study found that the daily average consumption of 4.1 oz. contributed 3.3% of the overall energy intake. Moreover, the consumers of 100% fruit juice showed a higher intake of vitamins C and B6, carbohydrates, potassium, magnesium, iron, riboflavin and folate.
Longitudinal studies into the subject remains relatively limited. However, one study that has employed the approach is the Dortmund Nutritional and Anthropometrical Longitudinally Designed (DONALD) Study. The study investigated the connection between the consumption of fruit juice and obesity (Alexy, 2009). The study also considered the relationship among anthropometric indices, fruit juice consumption and the overall diet in a three year period. The participants of the study were pre-school children who were taking part in the DONALD Study.
Two hundred and five children between the ages of 3 and 5 were selected for examination. Their dietary consumption was calculated using 3-day weighed records. The height of the participants was measured by a stadiometer while the weight was taken by an electronic scale.
From the study, it emerged that none of the children who consumed excess fruit juice became obese. Another finding was that there were no relationships between BMI, height standard and growth velocity and fruit juice intake. The study also affirmed that the consumption of fruit juice was negatively correlated with the intake of sweetened fruit. The study also established that the children who consumed excess fruit juice also took fat, protein and carbohydrates as nearly approved by international dietary guidelines.
Based on the findings, the research concluded that even excessive consumption of fruit juice could not influence anthropometric indices. This is because the results did not warrant issuing a warning or promotion of consuming high levels of fruit juice among children.
Evidence sourced scientifically indicates that the nutritional benefits associated with the consumption of fresh juice are immense. Overall, studies reflect that the consumption of fresh juice has an association with good health. Specifically, a high intake of fresh juice is associated with a lower consumption of saturated fats, dietary fats and added sugar (Nicklas, O’Neil & Kleinman, 2010, Nicklas, O’Neil & Kleinman, 2008). The main explanation for the state of affairs is that fresh juice has no added sugar. Research evidence shows that the absence of added sugar reduces the chances of becoming overweight. As established, there is no relationship between the consumption of fresh juice and obesity or weight gain (O’Neil et al., 2008; Pereira & Fulgoni, 2011).
Another research has positively established a link between fresh juice consumption and healthy living. Just as the other study, those people who consumed fresh juice also had a lower intake of added sugar, saturated fat and dietary fats (O’Neil et al., 2008).
The National Fruit & Vegetable Alliance (NFVA) showed that a bigger percentage of Americans consumed a significantly lesser amount of fresh fruit juice based on the recommendations of USDA’s Dietary Guidelines (O’Neil et al., 2012). As the NFVA found, only eight percent of the whole population and twelve percent of children were achieving the set fresh fruit consumption target.
In conclusion, it is clear that the topic that dominates attention is based on the widespread research that has been conducted. Nicklas, O’Neil & Kleinman (2010) used a cross-sectional approach in assessing the relationship between fruit juice intake and weight status. According to the study, those who did not consume juice were at a risk of consuming fatty and saturated food which predisposes people to an increase in weight. However, the study did not find any association between the consumption of fruit juice and weight status. Nevertheless, the researchers concluded that consumers of 100% fruit juice were highly unlikely to experience weight gain. While investigating the association between the two variables, Pereira & Fulgoni (2004) found an inverse relationship.
O’Neil et al. (2012) conducted a secondary analytical study using the National Health and Nutrition Examination Survey 1999-2002 data. The study was multiethnic and nationally representative. The research concluded that there was an absence of a statistically significant connection between 100% fruit juice and weight status. Moreover, pre-school children consumed approximately 6 oz. less of 100% fruit juice based on the recommendations of USDA Dietary Guidelines and the American Academy.
Ogden & Carroll (2006) and Alexy (2009) did not find any association between the consumption of fruit juice and weight status among studied participants. The speculated reason for the absence of correlation between fruit juice consumption and weight status is the absence of added sugar which Nicklas, O’Neil & Kleinman (2010) and Nicklas, O’Neil & Kleinman (2008) alleged was influential in weight statuses.
Obesity and its Costs
In order to understand the effects of obesity or overweight as serious concerns, focusing on research that has been sought to bring out the health and economic impacts of obesity is critical. In this section, the focus is on some of the studies that have investigated the obesity/overweight problem in relation to health and economic costs.
Obesity-associated costs affect not only the adult population, but also children. On an annual basis, childhood obesity costs were roughly 14.3 billion US dollars (Trasande & Chatterjee, 2009). In addition to the prevailing costs at the time, the future implication of obesity in terms of direct costs poses a serious dilemma (Serdula et al., 1993). Lightwood et al. (2009) estimated the future economic consequences that could emerge based on overweight or obesity among adolescents in the US. Based on their estimate, obesity and associated diseases will result in around forty five billion US dollars in direct costs between 2020 and 2050.
The economic angle of the relationship between obesity/overweight comes clear based on its predisposition to serious diseases. The model presented by Thompson, Edelsberg, Colditz et al. (1999) demonstrates the associations between BMI and risks of hypercholesterolemia, hypertension, type 2 diabetes, CHD and stroke. In conformity with his opinion, supported by the 1999 empirical study conducted on the basis of the San Diego hospital statistics, the rise of BMI exponentially increases the risk of being affected by the outlined physical disorders (Thomson et. al, 1999). Relying on the NHANES data, the model reflects on the direct and indirect costs associated with obesity and overweight. Moreover, other risks based on likelihood estimations are highlighted. Two most significant effects are on life expectancy and lifetime healthcare costs.
Related to the problem of obesity/overweight associated illnesses include diagnostic expenses and the actual treatment of the conditions. Studies such as case studies, cohort studies, nationwide representative surveys, dynamic models and regression analyses, and simulation forecasting are useful in carrying out such assessments. Although there are differences among the various studies, there is a consensus that the costs associated with overweight or obesity are substantial.
Thompson et al (1999) carried out a study where they sorted the subjects into three categories: obese, healthy and overweight based on the initial BMI of the subjects. After following the subjects for a period of nine years, they established that obese and overweight subjects incurred more accumulated costs than the healthy group. The groups had higher annual healthcare, prescription and primary care costs compared to the healthy group.
Pronk, Goodman, O’Connor & Martinson (1999) conducted a study assessing healthcare costs in a random sample. The population was members of a managed care enterprise. The subjects were over forty. The researchers focused on comparing costs based on the BMI of subjects. Thus, an increase in the BMI of an individual by one unit increased the median spending on health care costs by 1.9%.
Thompson et al. (1999) established that overweight increased the expected lifetime healthcare costs because of the mentioned above five diseases by roughly 20%. Further, the researchers found that obesity increased lifetime healthcare costs by up to 50%.
Gorsky, Pamuk, Williamson et al. (1996) conducted a research with the aim of assessing the association between medical costs and overweight/obesity. They constructed three cohorts containing 10, 000 women each. The cohorts had: healthy, obese and overweight women. The researchers began reviewing each group at the age of 40. The extrapolation was done through to the age of 65. The researchers were carrying out an incidence-based analysis on additional costs associated with obesity and overweight. Based on the results, the obese group would incur 3% more in medical costs annually.
Allison, Zannolli & Narayan (1999) considered if direct medical costs could be offset by an increase in mortality related to obesity. The researchers concluded that increased mortality lowered costs although the conclusion did not negate the notion that the costs remained substantial.
Other researchers such as Thorpe, Florence, Howard & Joski (2004) considered the relationship between overweight/obesity and spending. The researchers used self-reported data on two medical conditions and BMI from two representative samples. The researchers then controlled for individual variables such as smoking, demography, etc. The results showed that the healthcare expenditure increased by 12% as a result of the increase in the prevalence of overweight and obesity. Most of the spending was attributable to hypertension and diabetes.
The obesity problem is also associated with indirect costs as it is pointed above. Indirect costs gravitate around higher insurance premiums, premature mortality, and a decline in labor productivity. As Thompson (1999) established, the total costs of obesity to businesses in terms of paid sick leave and insurance were overwhelming. The study estimated obesity costs based on age and sex among businesses in the US. Based on the study estimates, in 1994 the costs associated with the problem stood at five billion US dollars. 2.4 billion, which is roughly 50% of the money, was spent on paid sick leave. The remainder was spent on insurance. Moreover, health-related complications cost roughly 7 billion US dollars.
Jacobson and King (2009) estimated costs associated with obesity and highway travelling in the United States. The researchers found a substantial cost was associated with the obesity problem as roughly 2.7 billion US dollars was spent on transport due to the obesity problem. The study found a relationship between an increase in the rates of obesity and the increase in transport costs.
Human capital is also a key area that is affected by obesity as has already been pointed. Obesity and overweight affect the quantity and quality of education. Thus, there is a likelihood that obesity/overweight will influence the economy. If the rates of obesity rise, there is a big risk that a society will face a sphere impact. Gortmaker et al. (1993) considered several variables in attempting to establish an association between obesity and overweight and educational performance, self-esteem, health conditions, or income. In the end, the study found that correlations between the four variables and obesity were statistically significant. Specifically, the study found that women who were obese spent fewer years schooling than those who were normal. Moreover, such women were less likely to secure marriage partners. The same case on marriage also applied to men.
In conclusion obesity is a serious health concern especially in the United States. Virtually, its effects cut across many facets of life. This view is held in reference to its role in social and economic aspects. Socially, the issue affects relationships. However, its economic impact is more demanding. In the literature it is pointed out that obesity has both direct and indirect costs to societies. For instance, Trasande & Chatterjee (2009) projected the costs attributable to obesity to stand at roughly 14 million US dollars in a year within the American society. Serdula, Ivery, Coates et al. (1993) and Lightwood et al. (2009) also estimated the costs associated with the epidemic. In their projections, obesity will cost the American society substantial amounts of resources as direct and indirect costs.
While testing a model, Thompson et al. (1999) demonstrated that obesity predisposed victims to more serious ailments. Such ailments as hypercholesterolemia, hypertension, type 2 diabetes, CHD and stroke are more demanding in terms of expenses attributable to diagnosis and treatment.
Pronk, Goodman, O’Connor & Martinson (1999) also considered the issue of costs associated with obesity. Based on the findings of the researchers, it was evident that larger BMI was correlated with increased healthcare spending. Another group of researchers estimated that overweight and obese people consumed roughly 3% more on healthcare than normal persons (Gorsky et al., 1996).
Some researchers were considering whether increasing mortality rates could be offset by direct costs (Allison, Zannolli & Narayan (1999). They held that increased mortality lowered costs although the conclusion did not negate the notion that the costs remained substantial.
Thorpe, Florence, Howard & Joski (2004) conducted a study and found that the healthcare expenditure increased by 12% as a result of an increase in the prevalence of obesity and overweight. A bigger percentage of the spending was attributable to hypertension and diabetes. Thompson (1999) established that the total costs of obesity to businesses in terms of paid sick leave and insurance were overwhelming. Finally, Jacobson and King (2009) found a substantial cost was associated to the obesity problem, as approximately 2.7 billion US dollars was spent on transport due to the obesity problem.
Orange Juice and Fruit Juice Contribution to Obesity
Orange juice is commonly consumed all over the world. It is extracted from oranges which explains its name “orange juice”. Though it is commonly consumed, the majority of the consumers have no idea of its effects on their bodies (Guenther, 1986). All they consider is quenching their thirst with a flavor they enjoy. With the consumption of orange juice, there are various effects it has on the human health. The juice contains nutrients that in one way, or another, affect the human body. Other than quenching human thirst, orange juice contains various vitamins, minerals and nutrients that each contribute differently to the human body especially when it is fresh with no preservatives (Guenther, 1986). It is often remarked that the fresher the juice is the better.
This research addresses the effects of pure, non-refined juice. This juice is directly extracted from the fruit and sold just as it is (ready to drink or the only change that will be made is addition of pure clean water to dilute the concentration of sugar which if it is too strong tends to irritate the throat). For the highest level of nutrition, the juice should be served at room temperature. This is because serving it chilled kills some of the nutrients which do not provide all the necessary requirements (Ballew, Kuester & Gillespie, 2000).
The absence of preservatives in fresh pure juice ensures that the body does not consume any chemicals used in the preservations. These preservatives are intoxicating if consumed frequently and in large quantities (Ballew, Kuester & Gillespie, 2000).
It is commonly known to contain vitamin C scientifically referred to as ascorbic acid which acts as an antioxidant in the body (Guenther, 1986). This protects the body from quick and early aging as well as prevents tissue damage through the collagen formation. Vitamin C is essential for healthy living as it influences the development of bones, teeth, gums and blood vessels. It aids in the absorption of iron and calcium in the body. Where the body is wounded, healing of the wound is more efficient with the consumption of vitamin C found in orange juice. It is also established that it is one of the components that help the brain in its functioning (Hyson, 2011).
A deficiency in vitamin C in the diet will lead to scurvy (Hyson, 2011). To prevent this, consumption of orange juice is helpful. Scurvy paves the way for fatigue and lethargy which affects the bones and muscle strength. Pregnant women need sufficient intake of orange juice in the diet as it helps in the development of the brain of unborn children (Hyson, 2011). This is due to the role of vitamin C. As this is not provided, one cannot correct the ailment after birth with the provision of the vitamin. Gum health can be restored in a natural way by consuming vitamin C found in orange juice (Hyson, 2011).
Bloody and weak gums can also be corrected by consuming orange juice. Orange juice also contains vitamin A which helps in the strengthening of the immune system which in turn will keep the body from being attacked by deceases. The growth and development of cells in the body is boosted by the consumption of the juice. Vitamin A keeps the mucous membrane and skin healthy, smooth and supple. Vision is also enhanced and maintained.
Orange juice also contains vitamin B9 commonly known as folate. This helps the human body in making of red blood cells and in making of DNA. Orange juice is also rich in fiber and pectin. On the other hand, it is low in calories and has no saturated fats making it suitable for persons watching their weight and those looking at cutting down on weight (Hyson, 2011). In lay man’s language, pectin protects the mucous membrane of the colon and also decreases cancer exposure. Other diseases suppressed by orange juice are chronic diseases like obesity and coronary heart diseases (Hyson, 2011).
The liquid from the juice keeps the body hydrated, in effect it improves the suppleness of the skin (Ballew, Kuester & Gillespie, 2000). If the skin is dehydrated, it ends up being wrinkled and dry resulting in the skin becoming scaly. It looks unhealthy.
Orange juice provides potassium which reduces chances of high blood pressure (Ballew, Kuester & Gillespie, 2000). Contraction and release of muscles is aided by the mineral potassium. So it contributes to the smooth travelling of nerve signals. In addition, it prevents minerals such as phosphorous and calcium from being lost from the bones, thus ensuring strong bones. Calcium and potassium work to achieve similar results.
Orange juice contains limonoids which when consumed remain in the body for up to twenty four hours. The substance is scientifically proven to help fight mouth, lungs, breast, skin, stomach and colon cancer more effectively than other sources that provide the same compound (Ballew, Kuester & Gillespie, 2000). Heart diseases caused by bad diets involving consumption of junk food, smoking and excess calories can be effectively prevented and treated with the consumption of vitamin C and pomegranate. Women, who take sufficient amount of orange juice are known to have a reduced risk of forming calcium oxalate stones commonly known as kidney stones as the PH level of their urine and citric acid excretion is increased (Guenther, 1986).
It comes out that the consumption of orange juice guards against unhealthy conditions. However, it has its own negative effects under certain circumstances. Orange juice is naturally acidic and in the event that an individual does not thoroughly rinse his mouth with water after consumption, the acidity stains the teeth. As a long-term effect, dental cavities and tooth decay occur (Guenther, 1986).
Individuals with diabetes can only consume this juice in moderation so as to avoid excess intake of the juice natural sugar as it will raise their sugar levels. As much as they are advised to consume natural sugar, excess of it has the same impact as synthesized sugar on their bodies which is hazardous (Guenther, 1986).
Orange juice is also not advisable for consumption among infants below the age of six months. It may lead to poor nutrition, abdominal pain, diarrhea, gas, and bloating (Ballew, Kuester & Gillespie, 2000). Infants cannot digest all the nutrients and minerals contained in the juice. In conclusion, pure orange juice has more benefits than shortcomings. The human body needs sufficient supply of orange juice for the provision of vitamin C, potassium, vitamin A, calcium and natural sugar which help in many different ways that have been observed. It is therefore essential to take orange juice. The source of the fruit is readily available and accessible across the globe at affordable rates.
Research on the Juice
A clinical research which entailed men consuming two cups of 100% orange juice reflected the beneficial attributes of the juice. As the study established, the consumption of the juice was correlated with a decline in the risks to experience cardiovascular conditions. Specifically, the consumers of fruit juice reflected improved vascular functionality and low levels of blood pressure. Research in support of this contended that hesperidin and orange juice had a direct influence on the shift in the health status of the consumers (Morand, Milenkovic, Chanet, Deval & Mazur, 2011). Another study being conducted bordering on vitamin D and calcium supplementation among obese adults indicated that the ones who consumed food servings with orange juice tended to show a high rate of reduction in their levels of visceral fat (fat that surrounds abdominal organs) (Moore, Rosenblum & Kaplan, 2011).
Rampersaud (2007) studied fruit juices in reference to their contribution to health. Focusing on the topic of nutrient-dense food, Rampersaud observed that the calorie content of the food was instrumental in understanding the worth of fruit juice in the diet. Although, 100% fruit juices have become common, they have different calorie volumes. The research by Rampersaud employed six approaches to reviewing the concentration of seven 100% fruit juices. Fruit juices included were: apple, grape, white grapefruit, pink grapefruit, orange, prune and pineapple juices.
A study by Boato et al. (2002) found out that it was essential to consume 100% fruit juice since it contains bioavailable Fe which is necessary for healthy growth as well as intellectual development among infants and growing children. Fruit juices remain highly nutritious since they are rich in Fe uptake inhibitors such as polyphenolic compounds (Boato et al., 2002). Fruit juices also have ascorbic acid which is highly helpful to growth. Based on this realization, an in-vitro digestion model was developed to compare the various effects of these juices: apple, grape, white grapefruit, red grapefruit, orange, prune and pineapple.
It has been found that orange juice does more good than harm in terms of the diet of consumers. Based on one study, adults who took 100% fruit juice were more likely to lead a better overall diet by consuming additional important nutrients. By consuming the critical nutrients, the persons in question were found to be at a reduced risk of becoming overweight than those adults who did not consume any fruit juice (Fulgoni, Rampersaud, O’Neil & Nicklas, 2012). Moreover, the research showed that children who took 100% orange juice enjoyed a better life in terms of health and consumption of other valuable nutrients.
The same study established that the consumption of 100% orange juice was linked to a 16% decline in becoming obese among adults. For the females, the results were even more encouraging since the consumption of fruit guaranteed a decline in becoming obese by 27%. These findings showed consistency with 2010 Dietary Guidelines for Americans which had concluded that consuming of 100% fruit juice had no association with body weight. Research by Gail Rampersaud of Florida University helped confirm this by disabusing the perception that 100% juice had an association with body weight.
There is a host of evidence that supports an absence of a link between weight gain and the consumption of 100% orange juice. A study by NHANES suggested that people who consumed 100% juice tended to depict higher levels of consuming other minerals/nutrients with positive effects on the health of the consumers. The nutrients include: iron, calcium, magnesium, folate, thiamin, carotenoids, vitamin B6, vitamin C and vitamin D. The study further affirmed the importance of consuming juice by establishing that the withdrawal of orange juice from the diet had a negative effect on the consumption of the said nutrients (Chun et al., 2011a).
A research assessment reached the conclusion that the intake of 100% citrus juice including orange and grape juice contributed significantly towards the decline in the chances of developing respiratory and digestive cancers. In addition, the study showed a correlation between the consumption of juices and a reduction in blood pressure as well an improvement in regards to bone health (Hyson, 2011).
Nicklas, O’Neil & Kleinman (2010) investigated the link between the consumption of fresh juice and nutrient intake and weight status. These scholars employed a cross-sectional design in collecting data from adolescents in the age bracket of 12-18. In total, they reviewed data relating to 3939 subjects. The participants were recruited from the National Health and Nutrition Examination Survey 1999-2002. The study employed the Logistic Regression and Least Square Means in analyzing the data. After generating the data it was adjusted for ethnicity, age, gender and energy intake. Upon this, the analyses were correlated with reference to a p value of .0125.
According to Nicklas, O’Neil & Kleinman’s (2010) study, 28% of the adolescents (only 51% of males, 42% of Hispanics, 29% of non-Hispanic black and 25% of non-Hispanic white) consumed fresh juice on the day of the appointment. On average, the amount of fresh juice consumed was 2.2% of the total energy intake. When these consumers of 100% fresh juice were compared to non-drinkers, the latter category was found to be at a higher risk of consuming higher amounts of fatty and saturated fats than consumers. As the research established, those who consumed more 100% fresh juice were also less likely to consume foods with added sugar than the non-drinkers. However, the research did not find any connection between weight gain or loss and the consumption of fresh juice.
However, based on the findings, the research concluded that adolescents who consumed 100% fresh juice showed a lower tendency to develop increased weight. It was also established that fresh juice offered critical nutrients. In addition, the research held that a higher consumption of fresh juice was associated with a reduced consumption of discretionary fat, saturated fatty acids, total fat, as well as added sugar. Moreover, the higher consumption of fresh juice was not related with a decline in the consumption of meat, milk or grains.
From the above studies, it is not easy to claim that obesity is influenced by fruit juice or soft drinks only. Other programs such as food programs have been associated with weight gain. On general terms, obesity is described as an unusual concentration of body fat around the body predisposing an individual to dangerous diseases. The issue of obesity is critical to everyone who is a part of our society: with 17% of all Americans being obese the chances that someone close to us is in this bracket or will soon slip into it are definitely high. It should be noted there are different types of obesity classified in order of severity or degree.
The classification that has received wide acceptance is the World Heath Organizations categorization. The WHO has three grades ranging from grade 1 to grade three based on Basal Metabolic Rate (BMI) scale (Jones, Jahns, Laraia, Haughton, 2003). Grade 1 obese cases are the least severe, they are categorized as ranging from 25 to 29.9 kilograms per meter squared of BMI, Grade 2 ranges between30and 39.9 kilograms per meter squared of BMI, while the most severe case normally referred to as morbid obesity characterizes the individual having a BMI equal to or exceeding 40 kilograms per meter squared. It is important to note that morbid obesity is indeed a serious health concern that can cause serious health issues including high blood pressure, heart disease, diabetes, sleep apnea and osteoarthritis. However, the above named classification takes into account such factors as sex, height and age to determine obesity (Kaushal, 2007).
Often soft drinks are assumed to contribute to an increase in the rates of obesity in the United States. This has led to conducting of studies to establish the authenticity of such allegations. For instance, O’Neil et al. (2012) conducted a study seeking to assess whether the consumption of 100% fruit juice was connected to weight gain. The primary objective of the study was to evaluate beverage consumption among pre-school children who took part in the National Health and Nutrition Examination Survey in1999-2002 with an aim to examine the connection between beverage-intake and weight status among pre-school children.
However, health concerns rising from the consumption of chemically produced fruit juice attracted much attention since such directions coincided with a rise in unhealthy conditions among consumers (Uzcudun et al., 2004). Although there are several aspects bordering on the consumption of chemically processed juices, obesity, heart diseases and bone diseases rank high (American Academy of Pediatrics Committee on Nutrition, 2001). This has contributed towards a reversal of trends as the preference for 100% fruit juice is gaining dominance.
The main component of fruit juice is water. The water is derived from the intracellular fluid of the fruits. This water is important in the metabolic processes as well as the preservation of cell turgor. The level of water varies depending on the fruit type. Another important substance is the non-aqueous portion which has several unidentified compounds such as natural sugar, sugar polymers, etc. (American Academy of Pediatrics Committee on Nutrition, 2001). These components are also useful to the body.
Apart from avocado, olive, oil palm fruit, ackee, other fruits have very low lipid content (Hollis, Houchins & Blumberg, 2009). In most cases, the content is less than five percent. The presence of low levels of lipids explains why fruit juice has low caloric effect in diets (O’Neil, Nicklas & Kleinman, 2010). This also explains why consumers of fruit juice are less likely to embrace fat diets.
As the literature shows, orange juice is among the most common juices consumed across the United States. Despite its nutritional value, as Guenther (1986) observed, a sizable percentage of consumers do not understand its worth. Guenther (1986) proceeded to observe that beyond quenching of thirst, by which most users rate the juice, it is also significant in contributing critical vitamins and minerals. By consuming 100 fresh juice, consumers escape taking in preservatives and other chemicals used in the product. Preservatives are intoxicating if consumed frequently and in large quantities, as observed by Ballew, Kuester, & Gillespie (2000).
Based on the above literature review, it is conclusive that the consumption of orange juice is important in guarding against unhealthy lifestyles. It has been found that orange juice does more good than harm in terms of the diet of consumers. Based on one study by Fulgoni, Rampersaud, O’Neil, & Nicklas (2012), adults who took 100% fruit juice were more likely to lead a better overall diet by consuming additional important nutrients. The persons in question, who consumed the critical nutrients, were found to be at a reduced risk of becoming overweight than those adults who did not consume fruit juice. Additionally, research has revealed that children who took 100% orange juice led a better life in terms of health.
Body Mass Index (BMI) Research
A large percentage of research on the topic has used the Body Mass Index as one of the study variables. The body mass index (BMI) is the most commonly used measure for obesity. BMI is obtained by dividing the weight by height squared. An individual whose BMI is more than 25 is considered overweight. On the other hand, an individual who has a BMI of thirty or more is considered to be obese. Overweight and obesity present serious health risks, e.g., several chronic illnesses, such as diabetes, cancer, and cardiovascular ailments. In the past, obesity was considered a problem that affected the high-income end of the population. However, trends have changed as obesity now affects low-income people as well.
In this section, researches that have touched on BMI in reference to the consumption of fruit juice are considered. Nelson, Carpenter and Chiasson (2006) sought to find out the physical activity and television viewing trends, as well as beverage and food consumption patterns. The relationship between the patterns was also reviewed in reference to weight status. The study selected children between the ages of 2 and 4 as its sample population. In assessing the dietary intake, questions were posed to parents. The outcome variable was the risk to become overweight. In the study, the covariates identified were based on demographics. The Chi-square test was used to assess the relationships.
The extent to which fruit juice was consumed was high. This is because 58% of the children consumed more than 8 oz., while 30% consumed more than 16 oz. of fruit juice per day. Consuming more than 8 oz. juice a day was associated with the risk of being overweight.
The only strength of the study was based on sampling a multiethnic population. However, the study was weak in a number of ways. For instance, the study was cross-sectional. Hence, it could not determine a cause-effect relationship. The dietary assessment was also based on questions posed to parents. The study also did not measure other aspects of the diet. The study concluded that there was no relationship between the consumption of 100% fruit juice and BMI.
Alexy et al. (2009) also conducted a study to evaluate the relationship between the consumption of 100% fruit juice (in the long run) and body weight and height. The study population was based on non-probability sampling. 205 children were sampled, 51% were boys and 49% girls. The sample was aged between three and five. The study lasted from 1990 to 1997. The outcome variables were growth velocity, BMI, and height standard deviation. The study was part of the DONALD study. The consumption of juice averaged 3.7 and 3.3 oz. a day, respectively. Approximately, nine percent of the children consumed more than 12 oz. per day, while ten percent consumed no fruit juice at all. Based on the study, those who consumed more than 12 oz. of fruit juice a day showed more restraint in consuming added sugars. However, their energy intakes were significantly higher. The study concluded that there was no association between BMI and the consumption of 100% fruit juice.
The longitudinal study had a major impact. The dietary data were taken from a weighed diary that was kept by parents. However, the study was weak in a number of ways. The sample was small, in addition to being from a single region. Moreover, the DONALD study sampled families interested in the long-term nutritional health of children. As already mentioned, self-reporting is subject to under and over reporting. Statistical analyses were also inadequately described. For instance, BMI is unadjusted in the analysis.
Based on the study by Alexy (2009), it emerged that none of the children who consumed excess fruit juice became obese. Another finding was that there were no relationships between BMI, height standard, and growth velocity with fruit juice intake. The study also affirmed that the consumption of fruit juice was negatively correlated with the intake of sweetened fruits. It also established that the children who consumed excess fruit juice also took fat, protein, and carbohydrates in amounts approved by international dietary guidelines.
Based on the results, the research concluded that even excessive consumption of fruit juice could not influence anthropometric indices. This is because the results did not warrant issuing a warning or promotion of consuming high levels of fruit juice among children.
It is also held that the length of time participants use food stamps for would influence obesity. In the past, long-term participation among non-elderly women was linked with higher levels of probability of weight gain. Other studies have found a similar relationship in the case of men (Jones & Frongillo, 2006). The implication is that BMI is associated with associated with food stamp use over a long time (Jones & Frongillo, 2006). Despite extensive literature on the topic, the link between the length of using food stamps and weight gain is unclear. However, it is hypothesized that there could be a variation between lengthy and shorter participation in the food stamp program. Other unanswered questions center on whether there are differences among children, women and men.
Non-elderly women, who form a large section of the beneficiaries of the program, are the only group that has shown a positive association between the food stamp program participation and weigh gain (obesity) (Guthrie, Frazao, Andrews, & Smallwood, 2007). Similarly, this group shows an elevated BMI. As such, previous studies have shown that the elderly women who participate in the program for roughly one to two years become obese and experience an increase in their BMI (Hofferth & Curtin, 2005). Based on this inference, a primary research question would be – is there an association between participation in the food stamp program and obesity or/and BMI? In addition to these statistics, another critical finding was that those people who consumed fresh juice also had lower Body Mass Indexes and waist circumferences compared to non-consumers (Pereira & Fulgoni, 2011).
Another study based on NHANES data established that adults who consumed 100% orange juice showed the tendency to having a small Body Mass Index, body fat, and waist circumferences, when compared to those who never drank the juice (Chun et al., 2011).
Chun et al. (2011) carried out a research that entailed analyzing the data by the National Health and Nutrition Examination Survey of 1999-2002. Over 1,500 participants (children between the age of two and five) were recruited. Nonetheless, only responses from 1,160 participants were used in the final examination. Based on the results, roughly 50% of the participants were male. On the basis of ethnic demographics, 28% were Black, 35% were White, while 37% children were Hispanic Americans. 24% of those sampled were obese or at risk of being overweight, given their Body Mass Index was larger than 85%. Nevertheless, approximately 11% were obese since their Body Mass Indexes exceeded 95%.
On the basis of the study conclusion, the variations between the Body Mass Indexes of the boys and girls were insignificant statistically. The same applies to the variations in races and ethnicities. Another key finding was that the older children (3.8 years and above>) seemed to be overweight compared to the younger ones.
On average, the study found that pre-school children consumed beverages totaling to 26 oz./day: 12 oz. of milk, 5 oz. of fruit juice, 5 oz. of fruit drinks, and 3.25 oz. of soda. Based on the results, the weight status was not related to the total level of beverages consumed. Furthermore, the study indicated that there was no clinically significant association between milk type and weight status. The findings also reflected an absence of statistically significant associations between 100% fruit juice and the weight status. In the end, pre-school children took 6 oz. less of 100% fruit juice when assessed against the recommendations of the USDA Dietary Guidelines and the American Academy.
Soft drinks sweetened by sugars account for up to 7.1 percent of the total energy consumption in the United States (Block, 2004). However, the juicy drinks are known to contribute towards unhealthy lives among its consumers. For instance, the rise in the incidence of type two diabetes and obesity in the country has been associated with the rise in the consumption of soft drinks, such as fruit juices (Bray, Nielson & Popkin, 2004). Research studies have shown a link between the consumption of fruit juices and the emergence of obesity in children (Ludwig, Peterson & Gortmaker, 2001; Mrdjenovic & Levitsky, 2003). One study found that the chances of becoming obese rose by approximately 1.5 times for every extra soft drink consumed each day (Ludwig, Peterson & Gortmaker, 2001). However, in the study, there was no association between consuming diet soda and childhood obesity.
Hill et al (2003) approximated that a shortfall of 100 kcal/d could lower weight gain. In order to reduce the calories, cutting down on the consumption of sweetened drinks could help. Hill et al contended that, in order to reduce the prevalence of weight gain, reducing the level of sugars in fruit drinks was mandatory. This is because a higher amount of calories is associated with the consumption of sweetened drinks. Based on the findings of Hill et al (2003), the reduction of sugars in soft drinks offered the best approach to solving the obesity problem. However, the study appreciated the need to alter behaviors, if any success was to be attained. For this to be effective, efforts from public health agencies, educationists, and other organizations must be made.
In the views of Hill et al. (2003), obesity has become a complex problem that is attributable to a combination of behavioral, environmental, genetic, and cultural influences. Thus, a shift at the individual level, social environment, cultural aspects, and policy frameworks could be helpful. Towards this end, the World Health Organization (WHO) has often outlined how chronic ailments, such as obesity, have negatively affected the world. In particular, the WHO report of 2003 criticized the beverage industry for employing high-level marketing practices in advertising their energy-dense products. The report called for restricting the intake of sweetened soft drinks in order to instigate a healthier lifestyle. In practice, the beverage industry has challenged the report claiming that it lacked scientific evidence on such issues as nutrient intake, obesity, quality of diet, etc.
Forshee and Storey (2003) considered the association between the consumption of beverages and choice subject to race, gender, age, and BMI. The population of the study was children between the age of six and nineteen years. The dietary assessment was on 2-24hr recalls. The study outcomes variable was BMI. Covariates differed depending on the model. Multivariate regressions were done on individual consumption models as functions of the independent variables.
The study focused on a large sample that was both multiethnic and nationally representative. The use of 2-24 hour recalls strengthened the study. The use of standardized data collection also enhanced the study’s strengths. The study was however cross-sectional and was state-based. Hence, it could not be used to determine the cause-effect relations. Self-reporting, an approach subject to under and over reporting, was also used. The study reached a conclusion that there was no association between the consumption of 100% fruit juice and BMI.
Several studies bordering on obesity and unhealthy drinking have centered on demographics. For instance, Huffman and West (2007) considered the biological aspects; Lee et al (2007) focused on the psychological attributes; Stevenson et al (2006) examined the behavioral features. As Epstein et al. (2001) upheld, high intake of sugary or energy-dense foods is partly responsible for the rise in the incidences of obesity. Epstein et al (2001) further found that a sedentary lifestyle and the consumption of nutrient-poor foods were partly to blame for the rise in the prevalence of obesity. This position is supported by a research conducted by Dufwenberg (2007), which called for a reduction in the consumption of unhealthy foods in a bid to reduce the obesity rates.
Past studies have also shown that health concerns are associated with the dietary trends (Sun, 2008). Glazer (2008) has also supported this position by asserting that the growing health concerns have led to a significant increase in the demand for healthy products. For instance, Landi (2007) found that, in the United States, consumers have become more conscious of the products they purchase, an aspect that has led to an increase in the demand for healthy products.
In conclusion, the following observations are made. When examining the relationship between 100% fruit juice and the obesity problem in the U.S., research on BMI is of utmost interest ( the research was focused on the evaluation of the states). As established above, many researchers have paid attention to fruit juice consumption and BMI. For instance, Nelson, Carpenter, and Chiasson (2006) found that consuming more than 8 oz. juice a day was associated with the risk of overweight. The study was based on a sample drawn from a multiethnic population. However, the study was cross-sectional. Hence, it could not determine a cause-effect relationship. The study reached the conclusion that there was no relationship between consuming 100% fruit juice and BMI.
Alexy et al. (2009) also conducted a study to evaluate the relationship between the consumption of 100% fruit juice (in the long run) and body weight and height. The study also concluded that that there was no association between BMI and the consumption of 100% fruit juice. Chun et al. (2011) conducted another study, based on NHANES, showing that adults who consumed 100% orange juice showed the tendency to having a small Body Mass Index, body fat, and waist circumferences when compared to those who never drank the juice. Forshee and Storey (2003) considered the association between the consumption of beverages and choice subject to race, gender, age, and BMI. Similar to most studies on the topic, the study also reached a conclusion that there was no association between the consumption of 100% fruit juice and BMI.
NHANES Research
As pointed out earlier, the National Health and Nutrition Examination Survey (NHANES) is the program of studies focusing both on health and nutritional statuses of people within the United States. The program is highly regarded as it offers unique data that combine physical examinations and interviews of participants. Introduced in the 1960s, it has been carried out a chain of surveys focusing on various groups of the population and health topics. Every year, the survey picks a sample of subjects using the random sampling approach from countries across the United States. The program study covers dietary, socioeconomic, demographic, and other health-related issues. The survey results are then used in estimating the prevalence of diseases and risk factors. Primarily, the NHANES data form the basis upon which the State’s national recommendations, measurements, and standards are set. The most important issue is that researchers have heavily relied on the data in conducting studies. Subsequently, some of the studies that have relied on the NHANES data are reviewed.
Several studies have been conducted in the field of health economics using the data by NHANES. In regards to the data by NHANES, moderate consumption of fresh juice among adults is linked with healthy lifestyles in addition to a reduced risk of becoming obese (O’Neil et al., 2012). Similarly, the same data showed that the rate of metabolic syndrome goes down among those people who consume 100% fresh juice. In addition to these statistics, another critical conclusion was that those people who consumed fresh juice also had lower Body Mass Indexes (BMIs) and waist circumferences compared to non-consumers (Pereira & Fulgoni, 2011).
Nicklas, O’Neil, & Kleinman (2007) conducted a cross-sectional study examining the association between the consumption of 100% fruit juice and weight status. The researchers picked a nationally representative sample from a population of adolescents. The dietary assessment was done based on only 24-hr recall. The outcome variables of the study included triceps skinfold, BMI-for-age percentile, weight, and BMI-age scores. The covariates included energy consumption, age, ethnicity, and gender. The consumption of 100% fruit juice was categorized into those consuming over and less than 12 oz.; however, there were two groups consuming between 0 and 6 and between 6 and 12 oz. of fruit juice in a day. The researchers employed the logistic regression in assessing adiposity outcomes and the risk of becoming overweight. The NHANES sample weighting was used in the analysis. The weights were, however, adjusted for the complexity of the NHANES sample design using SUDAAN.
Based on the study results, 28.4% of the participating population consumed 3.7 oz. of fruit juice, on average. Among the regular consumers, the mean consumption was 14.18 oz. a day. Those who consumed more than 12 oz. of the juice had higher energy levels than those who consumed lesser amounts. The researchers did not find differences in the adjusted adiposity or weight measures among the consumers. Similarly, the results did not show that juice consumers were likely to become overweight.
The study used a multiethnic sample that was largely representative. Another significant strength is that the study employed a standardized approach to collecting of data. More importantly, the study focused on 100% fruit juice. However, the study was cross-sectional, an aspect that reduces its worth in reference to the determination of cause and effect relationships. Moreover, the use of a single recall is questionable. It is also true that the study relied on self-assessment, which is subject to over and under reporting. The study concluded that there was no association between the consumption of fruit juice and adiposity or weight.
Focusing on the data by the National Health and Nutrition Examination Surveys (NHANES) of 2003-06, adolescents and children who consumed fresh juice enjoyed a more nutritious diet in comparison to non-fruit juice consumers (O’Neil et al., 2012). The primary reason was that fruit juice consumers had a higher intake of significant nutrients such as magnesium, folate, calcium, phosphate, potassium, and vitamins A and C. Another research has positively established a link between fresh juice consumption and healthy living. Just as the other study, those people who consumed fresh juice also had a lower intake of added sugars, saturated fat, and dietary fats (O’Neil et al., 2008).
O’Connor, Yang, and Nicklas (2006) also conducted a study with an aim of assessing the risks associated with overweight. The researchers were interested in establishing the differences between overweight or at-risk of overweight children consuming different beverages to normal-weight children. The study also sought to find out if the children who consumed more beverages were exposed to an increased risk to become overweight. The study sample included children aged two to five. The dietary assessment was based on 1 single 24-hr recall. The outcome variable was BMI, while the covariates included age, race, gender, income, physical activity, and energy intake. The consumption of juice was grouped into three groups. The first group included those who consumed between 0 and 6 oz., the second, between 6 and 12 oz., while the final group captured the group consuming more than 12 oz. a day. The researchers applied the Chi-square approach in testing associations among the groups. In addition, the researchers applied ANOVA to determine the association between beverage consumption and BMI.
Based on the study, 47.9% of the children consumed fruit juice, with the mean consumption standing at 4.7 oz. a day. The research further established that, as the intake of fruit juice increased, the energy intake also rose. Nevertheless, the research did not find a relationship between the consumption of 100% fruit juice and BMI. Moreover, the findings found no differences among the three categories in reference to weight status.
The study used a sample that was nationally representative. In addition, the study employed a standardized approach to collect data. Another critical strength is that the study factored in the BMI of those excluded from participating. There was no difference between the excluded and the included groups. However, the study was weak in that it used self-reporting and relied on a single 24-hr recall in its dietary assessment. The study reached the conclusion that there was no association between 100% fruit juice consumption and BMI. The research was part of the NHANES study of 1999-2002.
LaRowe, Moeller, & Adams (2007) conducted a study with the intention of assessing the beverage consumption patterns in relation to BMI. The study recorded data based on a single-24 hour recall. The study populations were made up of children between the ages of two to five and six to eleven. Outcome variables were BMI and BMI-age-sex percentiles. The study enlisted the following covariates: sex, age, ethnicity, physical activity, household income, birth weight, and media screen time.
The study established a difference between the juice cluster and the non-juice cluster in reference to energy intake. However, there was no difference in the BMI of the two groups. The study by LaRowe et al. (2007) was part of the wider NHANES study of 2001-02. The study used a nationally representative sample, although, after the adjustment for groups, the sample size reduced significantly. However, the data collection approach was standardized. The weakness lies in the use of a single recall in observing dietary intake. Moreover, the self-assessment report persists. The study concluded that there was no association between the cluster that consumed fruit juice and BMI among the participants between the age of two and five. High rates of overweight prevalence were found among the children falling under the milk cluster.
There is a host of evidence supporting an absence of a link between weight gain and the consumption of 100% orange fruit juice. A study by NHANES suggested that people who consumed the 100% juice tended to depict higher levels of consuming other minerals/ nutrients with positive effects on the health of the consumers. The nutrients include iron, calcium, magnesium, folate, thiamin, carotenoids, vitamin B6, vitamin C and vitamin D. The study further affirmed the importance of consuming the juice by establishing that the withdrawal of orange juice from the diet had a negative effect on the consumption of the said nutrients (Chun et al., 2011a).
Another NHANES study indicated that the adult people who consumed the 100% orange juice showed the tendency to having a lower BMI, body fat, and waist circumferences in comparison to those who never drank the juice (Chun et al., 2011). Another notable finding from the NHANES study was that adolescents and children who consumed the 100% orange juice stood a better chance to comply with the MyPyramid health recommendations, which call for limiting sugary and flavored foods (Sebastian, Enns, Goldman, Bowman, Moshfegh, 2011).
O’Neil, Nicklas, & Kleinman (2007) carried out a cross-sectional study with an aim of determining the association between the consumption of 100% fruit juice and nutrient intake and weight status. The population used was of children between the age of 2 and 11. The dietary assessment was based on a single 24-hr recall.
The outcome variables of the study included triceps skinfold, BMI-for-age percentile, weight, and BMI-age scores. The covariates included energy consumption, age, ethnicity, and gender. The consumption of 100% fruit juice was categorized into those consuming over and less than 12 oz.; however, there were two groups consuming between 0 and 6 and between 6 and 12 oz. of fruit juice in a day. The researchers employed the logistic regression in assessing adiposity outcomes and the risk of becoming overweight. The NHANES sample weighting was used in the analysis. The weights were, however, adjusted for the complexity of the NHANES sample design using SUDAAN.
Of the population, 43% consumed juice. The mean amount of juice consumption was 4.1 oz. in a day, while the mean among consumers was 10.6 oz. Consumers of more than 12 oz. showed a tendency of increased energy as compared to non-consumers. The study also did not find differences between adjusted adiposity and weight among the three groups. There was a likelihood of 2.9 to become overweight among the children (2-3 years), who did not consume juice, while the results showed 2.87 likelihood of overweight among children between the ages of 9 and 11, who consumed less than 6 oz. the study did not report any other relationships.
The study used a multiethnic sample that was nationally representative. Another noteworthy strength is that the study employed a standardized approach to collecting data. More importantly, the study focused on 100% fruit juice. However, the study was cross-sectional, an aspect that reduces its worth in reference to the determination of cause and effect relationships. Moreover, the use of a single recall is questionable. It is also true that the study relied on self-assessment, which is subject to over and under reporting. The study concluded that there was no association between the consumption of fruit juice and adiposity or weight.
Focusing on the NHANES data, O’Neil et al. (2012) established that adolescents and children who consumed 100% fruit juice enhanced their chances of taking such nutrients as magnesium, folate, calcium, phosphate, potassium, and vitamins A and C. The consumption of the minerals is critical in the sustenance of healthy living.
In conclusion, Nicklas, O’Neil, & Kleinman (2007) employed a multiethnic sample that was largely representative in assessing the relationship between weight status and fruit juice consumption. The study also employed a standardized approach in collecting data. More importantly, the study focused on 100% fruit juice. Nonetheless, the study was cross-sectional, an aspect that reduced its worth in reference to the determination of cause and effect relationships. Moreover, the use of a single recall is questionable. It is also true that the study relied on self-assessment, which is subject to over and under reporting. The study held that there was no association between the consumption of fruit juice and adiposity or weight. Similarly, O’Neil et al. (2012), analyzing data by NHANES, found that moderate consumption of fresh juice among adults was associated with healthy lifestyles in addition to a reduced risk of obesity. Similarly, the same data analysis showed that the rate of metabolic syndrome was lower among consumers of 100% fresh juice. Moreover, another critical establishment was that consumers of fresh juice also had lower Body Mass Indexes (BMIs), as well as waist circumferences compared to non-consumers, as established by Pereira & Fulgoni (2011).
O’Connor et al (2006) also conducted a study with an aim of assessing the risks associated with overweight. The research established that an increase in the intake of fruit juice precipitated an increase in the energy intake. However, the research did not find a relationship between consuming 100% fruit juice and BMI. Besides, the findings did not show any differences among the three categories in reference to weight status. LaRowe, Moeller & Adams (2007) also conducted a study with the intention of assessing the beverage consumption patterns in relation to BMI. Although the study established a difference between the juice cluster and the non-juice cluster in regards to energy intake, the study did not establish a difference in the BMI of the two groups.
O’Neil, Nicklas, & Kleinman (2007) carried out a study with an aim of determining the association between the consumption of 100% fruit juice and nutrient intake and weight status. The researchers concluded that there was no association between the consumption of fruit juice and adiposity or weight.
Pseudo Panel Research
As demonstrated earlier, Pseudo panel research is crucial in the research process. The significance of such research gains more value in the absence of complete panels, as observed by Moffitt (1993). Using pseudo panels is more relevant when there are repeated cross-sections. Theoretically, the need to use them is among the most holistic and important postulates that condition the practical application of the obtained results. The co-joint work of Ogden and his associates has proven that on the basis of the pseudo-panel findings, effective anti-obesity and anti-overweight strategies can be constructed. Moreover, using pseudo panels lowers the possibility of facing non-response and attrition concerns. Cohorts are functional in estimating the fixed effects of a model that stem from repetitive cross-sections, an aspect underscored by Deaton (1985). The average values within cohorts are viewed as observations that fall within pseudo panels. Hence, the approach is viewed as an instrumental variables methodology, where the clustering of variables represents the instrument. Here below, a number of studies are reviewed.
Skinner, Carruth, Moran, et al. (1999) conducted a study to assess whether a relationship existed between the consumption of 100% fruit juice and obesity among preschool children. The study population was made up of 105 children whose age was between 24 and 31 months old at the initial point. At the second point, the ages were between 27 and 36 months. The dietary assessments were done using the in-home interview approach. Two food records and two 24-hour recalls were carried out. The outcome variables included BMI, height, and PI. The study covariates were child age, maternal BMI and height, child gender, and age multiplied by gender. Two groups, on consuming more than 12 oz. and the other less than 12 oz., were examined in reference to height, PI, and BMI. After the comparison, the researchers applied the repeated-measures analyses to test the differences of the mean in the three variables between the two groups.
The mixed-model repeated-measures were used to test the differences in the means of the variables between the two groups. The data from the second interview were debarred from the analysis except those from the mixed models emanating from repeated measures. The participants in the study were also part to a larger longitudinal data, examining eating habits among children.
Based on the results, the consumption of 100% fruit juice averaged 5.5 oz. a day at the initial interview. During the second interview, the average consumption was 6.0 oz. The study concluded that there was no association between PI or BMI and the consumption of 100% fruit juice.
The main strength of the study rests on the employment of a longitudinal approach, which allowed for high retention. This was reflected in the realization that at the initial point, n = 105, while at the second point, n = 104. However, each study has its weakness. Specifically, this study used a small sample that was selected using convenience sampling. Thus, the sample was not diverse and lacked diverse representation. Similarly, the study’s two points are poorly described. In addition, reporting is not a commendable approach to data collection, since underreporting or over-reporting may undermine the accuracy of data. The original study failed to focus on fruit juice consumption either. Another issue with the study is that it failed to include other covariates, such as physical activities.
Field et al. (2003) assessed the association between fruit juice consumption and BMI. The researchers selected subjects between nine and fourteen years of age. Of the 16,886 subjects, 32% were boys. The period of the study spanned between 1996 and 1999. The dietary assessment focused on 131 types of food. The outcome variable was the BMI. In the study, activity, inactivity, tanner state, age, age squared, age/gender specific BMI scores, and height change were treated as covariates. The study controlled for total energy. To allow for time variation in exposure to treatments, conditional linear regression models were applied in multivariate analyses. The models focused on assessing the relationship between beverage consumption and changes in weight. These periods were examined: 1996-1997, 1997-1998, and 1998-1999. Based on the study outcomes, there was no relationship between the consumption of 100% fruit juice and BMI.
A notable strength of the study is based on the way the age and gender differences were modeled. The systematic biases attributable to reporting were evaluated in reference to height and weight. It was established that underreporting among heavier and taller cases existed. However, the weakness of the study is that it did not assess BMI. Moreover, self-reporting could distort the accuracy of the collected data. The study found no relationship between the consumption of 100% fruit juice and changes in BMI of the participants.
Newby, Peterson, Berkey, et al. (2004) conducted a study with the aim of determining the association between the consumption of beverages and changes in weight status among children who attended school. The study population was selected using the convenient sampling approach. The sample was aged between two and five years. The gender distribution was equal, but 83% of the participants were white.
The covariates in the study were based on sex, initial weight measures, height changes, social demographics, and total energy consumption. Linear regression analysis was employed in determining the relationship between weight status and beverage consumption. The change in weight was determined by subtracting weights between visit one and two divided by the time interval. Drinks were modeled as separate continuous models for each beverage before being modeled with the four models collectively. More analyses grouped fruit juice intake into consumption over and below 12 oz. a day.
From the study, girls’ average was 10.8 oz. a day; .55% of the girls consumed less than 12 oz. of 100% fruit juice a day. On the other hand, the boys’ average was 10.6 oz. a day; 54% of the boys consumed less than 12 oz. of fruit juice a day. The study reached the conclusion that there was no association between 100% fruit juice consumption and weight status. Moreover, there were no significant differences among those consuming more or less than 12 oz. 100% fruit juice in a day.
A notable strength of the study was to be found in its longitudinal approach. Moreover, the study sampled more than one race. However, the study showed some weaknesses in that it was not racially diverse. Thus, it could not be assumed as being representative. Another weakness is that the study was analyzed after six months despite being longitudinal. Another concern is that such aspects as parental BMI, television viewing, and physical activity were not included among the covariates.
Welsh, Cogswell, Rogers, et al. (2005) also considered the relationship between beverage consumption and obesity. The study covariates were age, race/ethnicity, gender, intake of fatty foods and sweet foods, birth weight, and total energy consumption. Data were collected based on two points after 11-13 months. One group consumed between 1 and 3 servings, while the referent group took between 0 and 1 serving of sweet drinks. Using the bivariate analysis, the researchers were able to evaluate the relationship between beverage consumption and overweight. The researchers proceeded to apply the logistic regression after adjusting it for the covariates. They then stratified the results using the baseline BMI.
The study established that there was no association between juice intake and being overweight among the normal weight and at-risk children groups. However, the association was found to be positive for those children, who were overweight at the baseline time. The study assessed weight variation at multiple points. It further gives detailed revelations on how it was conducted in terms of population selection in addition to portraying the differences of the people who were sampled. However, the idea of branding 100% fruit juice as sweet drink is highly questionable.
Skinner and Carruth (2001) have also contributed to research on weight status and the consumption of 100% fruit juice. The study had among its objective the need to determine the relationship between the intake of fruit juice and BMI, OI, Height, and weight. The study was also geared towards understanding beverage consumption patterns. Towards achieving that objective, the study used a conveniently selected sample of 72 children. 51% of the sample was made up of boys. The dietary assessment was based on seven in home interviews (2 food records and 24-hour recalls). Covariates of the study centered on growth parameters at 2 years, longitudinal energy consumption, gender, and the height or BMI of the parent. The statistical analyses focused on gender differences at 6 years, based on height, weight, and BMI. Repeated measures focused on the consumption of beverages over time. Generalized linear model relationships for each parameter and the consumption of 100% fruit juice were also considered. Children were grouped into overweight or normal. The means of juice consumption were also compared. Based on the study, the mean consumption of fruit juice was 5.4 oz. a day and was similar between the genders.
The levels of consumption continued to decline as time passed. Specifically, at the age of 27 months, the consumption was 6.8 oz. a day. However, at age of 72, the consumption was 3.6 oz. a day. The study upheld the position that longitudinal consumption of 100% fruit juice had no association with BMI. In the study, mothers were tasked with recording the diet behaviors. The retention rate stood at seven time points, indicating an excellent level. The study’s major weakness was based on its sampling. Its sample was conveniently selected from one region. Moreover, self-reporting was also employed in recording data. The p values were also not adjusted. Hence, the use of multiple comparisons in post hoc tests could prove misleading. The original study failed to focus on juice intake. Moreover, in the covariates, the exclusion of parental BMI, television viewing, and physical activity could have been a weakness.
Blum, Jacobsen, and Donnelly (2005) conducted research to assess whether there were differences associated with beverage consumption. Using BMI, the researchers sought to establish whether there were differences in SSB and milk consumption. The study also focused on establishing the predictors of BMI. The study was carried out in a two-year period. A sample of children was conveniently selected. Dietary assessment was based on a 24-hour recall period.
The study covariates included baseline BMI z-score, age, gender, Age ×Gender, specific beverages baseline consumption, energy intake, and beverage intake at the second year. The children were grouped into four groups: gained weight, normal weight, lost weight, and overweight. The researchers used T tests to gauge changes between the baseline and second year measures and beverage intake in every group.
The study used ANOVA repeated-measures and post hoc tests to come up with the differences in BMI scores from the baseline time to the second year. Regression analysis was then employed to establish the predictors of the BMI at the second year. The baseline beverage intake stood at 2.1 oz. at year 1 and 2.0 at year 2. The normal weight category subjects consumed 1.8 oz. of 100% fruit juice each day at the two periods. Based on the results, there was no significant difference among BMI grouped subjects and juice intake. The study does not, however, provide additional information.
A key strength of the study is that only subjects who took part at the two points were included. However, the study suffered from the fact that it was reexamining data on 100% fruit juice intake. Self-reporting was also used in the study. The study concluded that there was no relationship between BMI and fruit juice consumption.
Berkey et al. (2004) studied the association between changes in BMI and fruit juice, milk and diet soda consumption. The study population was 5,321 boys and 6,871 girls. The ages of the subjects ranged between nine and fourteen. The study was carried out between 1996 and 1998. Outcome variables were BMI changes over time. The covariates included BMI, physical activity and inactivity, non-liner age tendencies, and race/ethnicity. In mixed models, prior drinks consumption was included as a covariate. The study reported both cross-sectional and longitudinal analyses.
From the cross-sectional analysis, the association between fruit juice consumption and weight was unreported. However, the longitudinal analysis showed that there was no relationship between the two variables. This was a cohort-based study that used a large sample. The study also enjoyed a high response rate. Moreover, the study models, before and after adjustments for energy changes, were included. However, the study was subject to self-reporting. Despite the large size of the sample, it was not nationally representative.
Another significant study was conducted by Johnson, Mander, Jones, et al. (2007), who wished to determine whether consuming SSB posed a risk to an increase in fat mass. The study sampled children between the age of seven and nine. The gender and ethnicity of the participants were not reflected. The study relied on un-weighted food diaries to assess the dietary levels three times a day. Study covariates included television watching, parental BMI (adjusted for diet), and socioeconomic status. The study used the spearman rank correlation to assess the association between beverage consumption and log FMI. The study did not find an association between beverage consumption and body mass.
Faith, Dennison, Edmunds, & Stratton (2006) are among the researchers who have focused attention on the association between beverage consumption and weight status. They centered on a population of between one and five years. 1,797 participants were surveyed. The outcome variables were BMI scores. The baseline BMI, initial BMI, and parenting behaviors were chosen as covariates. In testing for a possible relationship between adiposity and beverage consumption, multiple regressions models were used.
Up to 53% of the participants consumed fruit juice. On average, the participants took 18 oz. fruit juice per day. The effect of consuming fruit juice on weight status was found to be insignificant. However, for the group of participants who were at-risk of being overweight, they exhibited an increase in BMI. Boys had a greater adiposity than girls. The main strength of the study was based on its use of an ethnically diverse sample. Moreover, results from study participants were compared with those of survey participants. Dietary intake was limited to limited to milk, fruit juice, and fruits.
In conclusion, the studies show no relationship between fruit juice and obesity. Those studies that do show a relationship point out that the relationship is statistically insignificant. Skinner, Carruth, Moran, et al. (1999) conducted a study to assess whether a relationship existed between the consumption of 100% fruit juice and obesity among preschool children. Based on the results, the consumption of 100% fruit juice averaged 5.5 oz. a day at the initial interview. During the second interview, the average consumption was 6.0 oz. The study concluded that there was no association between PI or BMI and the consumption of 100% fruit juice.
Newby et al. (2004) conducted a study with the aim of determining the association between the consumption of beverages and changes in weight status among children who attended school. The study reached the conclusion that there was no association between 100% fruit juice consumption and weight status. Moreover, there were no significant differences among those consuming more or less than 12 oz. of 100% fruit juice in a day. Welsh, Cogswell, Rogers, et al. (2005) also considered the relationship between beverage consumption and obesity. The study established that there was no association between juice intake and being overweight among the normal weight and at-risk children groups. However, the association was found to be positive for those children who were overweight at the baseline time.
The study by Skinner and Carruth (2001) also upheld the position that longitudinal consumption of 100% fruit juice had no association with BMI. Similarly, the research by Blum, Jacobsen and Donnelly (2005) reached the same conclusion, that there was no significant difference among BMI-grouped subjects and juice intake. The study does not, however, provide additional information.
Johnson, Mander, Jones, et al. (2007) also found that there was no association between beverage consumption and body mass. Faith, Dennison, Edmunds & Stratton (2006) also considered the association between beverage consumption and weight status. From the study, the effect of consuming fruit juice on weight status was found to be insignificant.
Based on the cross-sectional research studies, determination of the cause-effect relationship is difficult. However, researchers are able to discern the nature or absence of a relationship between variables by applying longitudinal data and using appropriate covariates.
Literature Conclusion
It is evident, based on the literature review, that obesity-associated costs affect not only the adult population, but all populations. Annually, childhood obesity costs were roughly 14.3 billion US dollars, as presented by Trasande & Chatterjee (2009). Moreover, the future implication of obesity in reference to direct costs posed a serious dilemma, as observed by Serdula, Ivery, Coates et al. (1993). Similarly, Lightwood, Bibbins-Domingo, Coxson, et al. (2009) estimated that the future economic consequences attributable to overweight or obesity among adolescents in the US could be around 45 billion US dollars in direct costs between 2020 and 2050.
Nearly all nutrition-based studies rely on a questionable approach in data collection. The studies depend on participants’ self-assessment. The reliance on self-assessments could compromise the accuracy of measures. Hence, although evidence from cross sectional data-based research has shown a positive relationship between the consumption of 100% fruit juice and weight status, such findings could be limited. Dennison, Rockwell, and Baker (1999) compared the consumption data using NHANES data. The study was limited since it had overlapping populations, a concern spotted by Dennison, Rockwell, Nichols, & Jenkins (1999). The effect of overlapping populations is on the possible prejudice that interpretations would make regarding the relationship between variables. Other cross-sectional data-based studies have relied on responses from self-assessors (Dennison, Rockwell and Baker 1999 and Dennison, Rockwell, Nichols & Jenkins, 1999). Dennison, Rockwell and Baker (1999) established that children who consumed over 12 0z of 100% fruit juice showed an increase in their BMI. The results also revealed that they were at a higher risk of becoming obese than those who consumed lesser amounts.
Longitudinal studies have also had their weaknesses. For instance, the longitudinal study by Alexy (2009) had major weaknesses. The sample was small, in addition to being from a single region. Moreover, the DONALD study sampled families interested in the long-term nutritional health of children. As mentioned in the literature, self-reporting is prone to under and over reporting. Statistical analyses were also inadequately described. For instance, BMI is unadjusted in the analysis.
It emerges that sampling is a major concern in most of the reviewed studies. Thus, apart from conducting longitudinal study, selecting an-all inclusive sample that is representative is crucial.
Longitudinal data are useful in a bid to remedy shortcomings of cross-sectional data-driven research studies. It is recognizable that cross-sectional research designs depend on the nature of research questions, as Carlson et al. (2001) observed. When reviewing the relationship between consuming 100% fruit juice, obesity and healthcare costs, it is significant to determine an approach that leads to a comprehensive understanding of such a relationship. When a researcher is interested in establishing the relationship at one point, the cross-sectional approach is preferred. On the other hand, when considering the relationship of variables at different points, the focus should be on the longitudinal approach to data collection and analysis.
Nonetheless, cross-sectional data may not be authoritative or informative on cause and effect associations, as argued by Carlson et al. (2001). The studies do not judge the pre/post conditions surrounding the research participants. As a consequence, in evaluating the relationship between the fruit consumption and obesity, it could be difficult to know the weight levels of the persons being studied before the research.
Moreover, Carlson et al. (2001) proceeded to observe that the main benefit of using longitudinal data lay on its ability to measure change over time. Hence, it is possible to estimate the effect of different factors on a given variable. On the whole, the effect of a variable on another can also be estimated. In addition, longitudinal data cover past and present data. This allows for the evaluation of the effects of a specific change in the variable. Furthermore, longitudinal data facilitate using analytical strategies to gauge the influence of various factors on given variables.
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