BOSTON – Greater consumption of sugar-sweetened beverages was associated with a more pronounced genetic predisposition to elevated body mass index (B.M.I.) and obesity risk, according to researchers from the Harvard School of Public Health who examined three studies. Results of their research appeared on-line Sept. 21 in The New England Journal of Medicine.
In response, the Washington-based American Beverage Association said, “We know, and science supports, that obesity is not uniquely caused by any single food or beverage. Thus, studies and opinion pieces that focus solely on sugar-sweetened beverages, or any other single source of calories, do nothing meaningful to help address this serious issue.”
The published research involved 6,934 women from the Nurses’ Health Study, 4,423 men from the Health Professionals Follow-up Study and 21,740 women from the Women’s Genome Health Study. The researchers classified people with a B.M.I. of 30 or higher as obese. Participants who were obese at baseline were excluded from the analysis.
Sugar-sweetened drinks included caffeinated colas, caffeine-free colas, carbonated non-cola soft drinks and non-carbonated sugar-sweetened beverages such as fruit punches, lemonades and other fruit drinks. Four categories of beverage intake were used: less than one serving per month, one to four servings per month, two to six servings per week, and one or more servings per day. The combined genetic effects on B.M.I. and obesity risk among people who drank one or more servings of sugar-sweetened beverages per day were about twice as large as the risk among people drinking less than one serving per month.
In the Nurses’ Health Study, researchers found 1,107 cases of obesity among 6,402 initially non-obese women during 18 years of follow-up between 1980 and 1998. In the Health Professionals Follow-up Study, they found 297 cases of obesity among 3,889 initially non-obese men during 12 years of follow-up between 1986 and 1998. In the Women’s Genome Health Study, they found 2,280 cases of obesity among 18,127 initially non-obese women during six years of follow-up between 1992 and 1998.
While follow-up data from the study ended in 1998, the American Beverage Association, a trade association that represents America's non-alcoholic beverage industry, said since then intake of sugar-sweetened beverages has fallen. According to the A.B.A., caloric intake from sugar-sweetened beverages declined by more than 20% between 2001 and 2010, the average number of calories per beverage serving is down 23% since 1998, and about 45% of all non-alcoholic beverages purchased now have no calories.
The Harvard researchers pointed out drawbacks in their study. For one, the proportion of the total energy intake derived from sugar-sweetened beverages was not evaluated. For another, the study was restricted to people of European ancestry.
Sugar-sweetened beverages account for about 7% of the calories in the average American’s diet, according to the A.B.A.