Sugar-sweetened beverages, milk intake, and obesity in children and adolescents.

In their study, absolute quantities of milk consumed decreased by 25% and sugar-sweetened beverage consumption increased almost 3-fold over a 10-year period. Soda consumption, but not the consumption of other beverages, predicted the greatest increase in body mass index (BMI). Because changes in BMI rather than incident obesity were measured, the authors are appropriately careful not to ascribe obesity to increased soda consumption. Soda consumption was also associated with a statistically significant decrease in calcium intake. Because milk provides an important source of calcium in the diets of children and adolescents, the decline in girls’ milk consumption at a time when bone mineral deposition may predispose to eventual osteoporosis is a major concern. Several studies have indicated that in children and adolescents, sugar-sweetened beverage consumption as a percentage of total caloric intake has increased and milk consumption has decreased over the last 20 years. The same studies found that sugar-sweetened beverages accounted for 5% to 10% of caloric intake among children age 2 to 16 years. Although a reciprocal relationship between milk and sugarsweetened beverage intake often exists, these studies do not irrefutably demonstrate that increased sugar-sweetened beverage consumption leads to decreased milk consumption. However, 1 study demonstrated that when a small sample of 6to 13-year-old children at a 4to 8-week summer day camp were offered both milk and fruit-flavored sugar-sweetened beverages, the children’s milk consumption was significantly lower when they consumed more than 16 oz/day of sugar-sweetened beverages compared to when they consumed no sugar-sweetened beverages. With respect to the relationship of sugar-sweetened beverage consumption and excessive weight gain, the evidence that an association is causal depends on several characteristics. The criteria include statistically significant associations, specificity, consistency, a temporal relationship, a dose-response effect, and biological plausibility. As shown in the Table, the longitudinal observational studies that have examined the relationship of sugar-sweetened beverages to various measures of obesity meet many of these criteria. These studies used variable measures of sugar-sweetened beverages, such as soda and 10% fruit juice. Various weight-related measures were used as outcome measures, including changes in BMI, BMI z-score, percentage of body fat, and prevalence of obesity. The relationship of sugar-sweetened beverage consumption to excessive weight gain was generally statistically significant, but the effect sometimes varied across groups within the same study. In those studies that controlled for other variables likely to influence weight gain, the associations were specific for sugar-sweetened beverage consumption. Sugar-sweetened beverage consumption preceded the effect on the weight-related measures. A dose-response effect was found in several of the studies. A logical mechanism exists that can explain this association. Consumption of excess calories can produce weight gain. The high fructose content of sugarsweetened beverages may promote hepatic lipogenesis, and the reduced insulinogenic response may decrease the inhibitory effects of these sugar-sweetened beverages on food intake. In addition, significant weight gain may occur when carbohydrates are consumed as liquids rather than as solids. The potential contributions of sugar-sweetened beverages to weight gain are supported by the results of several controlled clinical trials in adults. Adults fed almost 1135 g/day of high-fructose corn syrup–sweetened beverages gained weight; when they were fed the same amount of beverages with an artificial sweetener, men, but not women, lost weight. In a study of overweight adults fed supplements of 152 g/day of either sucrose or artificial sweeteners, predominantly in the form of beverages, those who See related article, p. 183.