A Juicy Approach to Health

A significant body of evidence indicates protective health benefits result with an increase in consumption of fruits and vegetables. From a global perspective, approximately 1.8% of the total burden of disease may be related to insufficient consumption of fruits and vegetables, which is comparable to 2.3% for overweight and obesity.

Overall, the World Health Organization (WHO) estimates that low intake of fruits and vegetables is among the top 10 risk factors for disease, resulting in annual deaths of nearly 2.6 million worldwide. The estimated levels of fruit and vegetable intake vary around the world, ranging from less than 100 g/day in less-developed countries to nearly 450 g/day in developed countries. an expert report on diet, nutrition, and prevention of chronic diseases from WHO and the Food and agriculture Organization (FAO) recommends a minimum of 400 g/day of fruits and vegetables to prevent chronic diseases, such as heart disease, cancer, diabetes, and obesity. WHO’s findings indicate that the disease burden is reduced by a fruit and vegetable intake of up to 600 g/day.

From a U.S. perspective, the 2005 Dietary Guidelines Advisory Committee Report, upon which the Dietary Guidelines are based, recommends 2 cups of fruit and 2.5 cups of vegetables for a reference 2,000-calorie diet. Depending upon the caloric needs, the total number of fruit and vegetable servings recommended can range from 9–13 servings per day. Within the Dietary Guidelines recommendations, 100% fruit juice can count as a fruit serving. Although the guidelines state that most fruit servings should come from whole fruits, a portion of the daily fruit intake can be from 100% fruit juice.

Fruit juice consumption is a leading source of daily fruit servings for many individuals. While 100% fruit juice contains most of the characteristics of the original fruit, differences do exist between whole fruit and fruit juice. Therefore, questions can arise concerning caloric density of juices, adequate nutrient intake with juice consumption, and nutritional quality of processed fruit.

Juice is naturally sweet and can be energy dense; therefore, the assumption is made that most children and adults may consume too much. As of late, consumption of juice has been under attack by some scientists and various media outlets due to limited studies that suggest overweight status in children is linked to 100% juice consumption. The entirety of the scientific evidence is contradictory to this notion, however.

A recent review assessed the relationship between 100% fruit juice consumption and weight in children. The authors evaluated nine cross-sectional studies. Only three studies reported an association, albeit a weak association, between juice consumption and overweight status. It is important to note that these three studies were small, the subjects did not represent national demographics, and the subject selection criteria were not well defined.

In addition, another assessment was made on 12 longitudinal studies. Just three of these studies showed an association, with two of the three studies being completed in overweight children. Again, none of the 12 longitudinal studies was nationally representative; however, five of these studies had more than 1,000 participants, three had different geographic sites, and two had an ethnically diverse group of participants. The authors concluded that, at present, there is no systematic association between consuming 100% juice and being overweight in children and adolescents.

The American Academy of Pediatrics Policy Statement recommends children ages 1–6 should consume no more than 4–6 oz/day of juice. For children ages 7–18, the recommendation for juice consumption is 8–12 oz/day. Evidence indicates that mean consumption of 100% juice by children and adolescents is within these recommendations.

A recently published study investigated the association between 100% juice consumption, nutrient intake, and weight in children. The National Health and nutrition Examination survey 1999–2002 data were used to identify children 2–11 years of age to determine types and amounts of food and beverages consumed over a 24-hr period. Of the 3,618 children, the average daily intake of 100% juice was 4.1 oz, which is well within the recommendations. Relative to non-juice consumers, juice provided significantly higher intake of energy, carbohydrates, fiber, vitamin C, vitamin B-6, potassium, riboflavin, magnesium, iron, and folate. Also, for those consuming juice, intake of sodium, fat, saturated fat added fat, and added sugar were lower. in addition, 100% juice consumption was not associated with any of the physiologic weight measures studied. Overall, the conclusion was made that 100% juice consumption is not excessive, contributes essential nutrients in children’s diets, and does not have an adverse effect on children’s weight.

Fruit juices (100%) are valuable sources of essential vitamins and minerals, which contribute to overall dietary quality and thus may reduce the risk of chronic diseases. In addition, various juices can be a major source of numerous polyphenols, particularly flavonoids, in the diet. Researchers have found fruit juice consumption can contribute significantly to adequate intakes of essential nutrients, including vitamin C, folate, potassium, and magnesium. Fruit juice can help meet the needs of identified nutrients of concern or shortfall nutrients as outlined by the U.S. Dietary Guidelines.

Given the fact that there is an increased focus on energy balance, the FDA, as well as other food and nutrition experts, have considered communicating nutrient density (quantity of nutrient per calorie provided) on a food label by computing a nutrient density score. In a recent study, seven different 100% non-fortified fruit juices, including apple, grape, pink grapefruit, white grapefruit, orange, pineapple, and prune were analyzed for their nutrient density, using six different methodologies. The results indicated very similar nutrient density rankings of the juices for all methodologies used. In addition, citrus juices, particularly pink grapefruit and orange juice, consistently provided higher nutrient density scores relative to the other juices tested. keep in mind that nutrient density scoring has limitations, which include not accounting for nutrition fortification and nutrient bioavailability as well as the phenolic profile. Some scientists question the trade-off between calories vs nutrients provided by 100% juices. However, given the nutrient density and phenolic profiles of 100% juices, emerging evidence suggests fruit juice consumption may be as effective as consumption of whole fruit in relation to reducing risk of certain chronic diseases.

Of the most commonly consumed juices (orange, grapefruit, apple, and mango), orange juice has the greatest number of human intervention studies. kurowska et al. (2000) conducted a study to investigate the role of orange juice on cardiovascular health in 25 subjects with mild-to-moderate hyperchol-esterolemia. This study indicated that consumption of 750 ml of orange juice every day for 4 weeks improved the plasma lipid profile. The improvement was based on a significant increase in HDL-cholesterol concentrations and a reduction in LDL-HDL cholesterol ratio.

Franke et al. (2005) examined the effect of orange juice consumption on antioxidant status and cardiovascular disease risk markers. During the 3-week intervention study, 13 healthy adults consumed 710 ml of orange juice (not from concentrate) in addition to their regular diet. Due to the consumption of orange juice, the participants consumed an additional 256 mg vitamin C, 271 mg of flavanones, 6 mg of carotenoids, and 0.16 mg of folate daily. At the end of the study, mean vitamin C, folate, carotenoid, and flavanone plasma concentrations increased relative to baseline by 59%, 46%, 22%, and eightfold, respectively, with no change seen in plasma concentrations of vitamins A or E. LDL/HDL cholesterol ratios decreased slightly, but HDL, LDL, and total cholesterol did not change. A significant increase in triacylglycerol concentration was observed, perhaps reflecting an increased total carbohydrate intake. These results relating to blood lipid parameters may have been more pronounced in a hypercholesterolemic population.

Antioxidants particular to citrus fruit, such as the flavanones naringenin and hesperetin, are significant contributors to the traditional antioxidant profile of orange juice. Various studies have been conducted to measure hesperitin and naringenin metabolites after consumption of orange juice in a small number of healthy volunteers. These studies demonstrated plasma concentrations of the various flavanones as glucuronides and sulpho-glucoronides achieved peak levels 5-7 hours postprandial when consumed by healthy young adults. Like these studies, most human trials involving consumption of juice have been short-term investigations with a small number of participants. Longer-term human trials are warranted to assess potential physiological effects and clinical benefits.

Consumption of 100% juice is an effective approach to meet the current dietary recommendations for fruit intake, as well as provide essential nutrients. Substantial evidence indicates 100% juice can be part of a healthy, active lifestyle and does not contribute to weight gain when consumed in moderation.

References for the studies mentioned above are available from the authors.

by Roger Clemens,
Dr.P.H., Contributing Editor 
Special Projects Advisor, ETHorn, La Mirada, Calif. 
[email protected] 

by Joy Dubost,
Ph.D., R.D. 
IFT Food Science Communicator 
[email protected]