Soda at Your Peril
Sugary drinks, but not fruit juice, may be linked to insulin resistance
It might be a good idea to hold off on that can of soda with lunch. Researchers have found that higher consumption of sugar-sweetened drinks may be associated with insulin resistance, a precursor to type 2 diabetes, even in otherwise healthy adults. But there is some good news: consumption of 100 percent fruit juices showed no such effects.
Noting the parallel growth in consumption of sugar-sweetened beverages and the rates of type 2 diabetes mellitus over the last several decades, Tufts nutritional epidemiologists devised a study of 2,500 healthy men and women who were participants in the Framingham Offspring Study, an offshoot of the long-term Framingham Heart Study. In the new study, published in the Journal of Nutrition, participants who drank two or more sugar-sweetened beverages per day showed significantly higher fasting blood levels of insulin compared to those who drank none, regardless of age, sex, weight, smoking status or other dietary habits.
“Higher fasting levels of insulin mean these study participants are more at risk for developing type 2 diabetes,” says Paul Jacques, a professor at the Friedman School of Nutrition Science and Policy and director of the Nutritional Epidemiology Program at the Jean Mayer USDA Human Nutrition Research Center on Aging. “In contrast, consumption of 100 percent fruit juice was not significantly related to any of our measures of insulin resistance.”
But don’t go out and stock up on fruit juice to replace those sodas, says Nicola McKeown, a scientist in the nutritional epidemiology program at the Human Nutrition Research Center. “While 100 percent fruit juice can be a healthful beverage, too much fruit juice can add excess calories and sugar to the diet,” she says. “Whole fruit is often a better choice.”
Jacques and McKeown also caution that their results cannot be used to determine cause-and-effect relationships among caloric and non-caloric sugar-sweetened beverage consumption and insulin resistance. “It could be that people who drink sugar-sweetened beverages have other unhealthy behaviors that we did not account for,” says McKeown. “Sugar-sweetened drink consumption may prove to be an important determinant of insulin resistance, but more long-term studies of diverse populations that incorporate the use of more direct measures of insulin resistance are needed.”
In the meantime, they suggest that people continue to follow the recommendations in the 2005 Dietary Guidelines for Americans, increasing consumption of water while limiting intake of calorically sweetened, nutrient-poor beverages.This story ran in the December 2007 issue of the Tufts Journal.