Some nutrition scientists attribute the increase in obesity in the U.S. to the corresponding increase in soft drink consumption that occurred between 1977 and 1997. A few would go one step further and link the increase in obesity to the fact that–in the 1980s–most soft drink, fruit punch, and snack manufacturers switched from refined cane sugar to corn sweeteners. This school of thought relies on preliminary research suggesting that high-fructose corn syrup is metabolized differently than other sugars with the potential for causing more adverse health effects.
A new study of young and middle-aged women found that those who drank the most sugar-sweetened beverages (i.e., with high-fructose corn syrup) showed greater weight gain and an increased risk of type 2 diabetes. The findings came from the more than 51,000 women who were drawn from a much larger research project called the Nurses’ Health Study. All had filled out questionnaires about their dietary habits and health information at three-year intervals during the 1990s. The study, conducted by the Harvard research team led by Matthias B. Schulze, DrPH, was published last month in the Journal of the American Medical Association. It was funded by the National Institutes of Health.
No difference in weight gain was reported by the women who did not change their consumption of soft drinks and fruit punch. But the highest weight gain was among those who had increased their sugar-sweetened beverage consumption from one or fewer drinks a week to one or more drinks per day. Though these soft drinks have plenty of calories, they do not make a person feel full, according to Dr. Schulze and colleagues. The smallest weight gain was reported by women who decreased their intake.
The incidence of type 2 diabetes increased among the women who consumed one or more sugar-sweetened soft drinks per day, compared with those who drank less than one a month. Those who had increased their intake of fruit punch gained more weight than those who decreased their consumption. Schulze and colleagues speculate that the larger weight gain and higher risk of type 2 diabetes shown among those with high intake of sugar-sweetened beverages is due to excessive calories. Additionally, the researchers pointed out that the high-fructose corn syrup in these soft drinks becomes rapidly absorbable sugars. This raises the insulin drastically, putting stress on the insulin-producing cells of the pancreas.
The researchers explained the difference between fruit juice and fruit punch. The latter contains large amounts of added high-fructose corn syrup and only a small amount of fruit juice. “Fruit juice consumption was not associated with diabetes risk in our study, which suggests that naturally occurring sugars in beverages may have different metabolic effects than added sugars.”
The women who drank the most sugary drinks tended to consume more calories overall, to be less physically, active and to smoke more.