Impact of glycemia and energy balance on metabolic risk in healthy subjects
In epidemiological studies, consumption of sugar-containing beverages is associated with an increased risk of type 2 diabetes and hyperuricemia. The aim of this crossover intervention study in 26 healthy young adults was to investigate, whether orange juice (OJ) has the same negative effects on metabolic risk as cola. Participants consumed 20% of their individual energy requirement in form of caffeine-free cola or OJ for two weeks. Despite the same amount of sugar intake, the consumption of cola resulted in higher daylong glycemia as well as a higher glucose variability and a lower C-peptide excretion as marker of insulin secretion. In addition, the consumption of OJ led to a decrease in uric acid levels and increased uric acid excretion. Regular consumption of OJ could therefore have protective and therapeutic effects on hyperuricemia and gout. The results of this study show that epidemiological associations need to be reviewed through intervention studies, and that the effect of sugar-containing drinks on health can not be limited to their sugar content. In a second study, the impact of low intensity physical activity on postprandial glycemia was studied in 16 healthy young adults independent of energy balance. Study design was created based on the energy turnover model. Subjects were investigated under three different activity levels walking on a treadmill. Postprandial glucose and insulin levels were improved by increasing postmeal physical activity. The reduction in postprandial glycemia was shown with zero energy balance, caloric restriction and overfeeding, and was thus independent of the energy balance and presumably due to insulin-independent glucose uptake. On the other hand, low intensity physical activity had no effect on 24-h glycemia in healthy normoglycemic subjects. The results of this study show that a moderate increase in daily activity is sufficient to improve postprandial glycemia.