Harvard School of Public Health researchers found that a greater consumption of sugar-sweetened beverages is linked with a greater genetic susceptibility to increased risk of obesity and high body mass index.

The HSPH study, published in the New England Journal of Medicine, reinforced the view that genetic and environmental factors interact to increase obesity risk.

“If people have a higher genetic risk for obesity, the effects of obesity will be exaggerated by the sugar-sweetened beverages,” said Qibin Qi, a HSPH research fellow and the lead author of the study.

“This provides some evidence to people to reduce their intake of sugary beverages, especially for people who are at a high genetic-risk for obesity,” he said.

Researchers looked at data from three other large HSPH studies: 121,700 women in the Nurses’ Health Study, 51,529 men in the Health Professionals Follow-up Study, and 25,000 in the Women’s Genome Health Study. Participants completed questionnaires detailing their food and drink consumption over time.

“Dr. Qi and his colleagues have been able to do this study in a longitudinal way in this type of analysis,” said Ruth J. F. Loos, director of the Genetics of Obesity and Related Metabolic Traits Program at the Mount Sinai School of Medicine. “This is a large study…It’s very well designed and well presented.”

The results indicated that the genetic effects on obesity risk and body mass index among those who drank one or more sugar-sweetened beverages per day were twice as large as those who consumed less than one serving per month.

“It’s hard to say that it’s a specific physiological effect of these sugar-sweetened beverages,” Loos said. “I think it’s that it’s an overall unhealthy lifestyle that makes them more genetically susceptible.”

Loos said that people who drank more sugar-sweetened beverages were often less active.

“They have a poor quality of diet and a high BMI, so you already see that sugar-sweetened beverages are actually maybe just a proxy for these effects.”

Qi said that they will continue to explore other genetic factors or dietary and lifestyle factors and their interactions in relation to obesity and other chronic diseases.

“[The study] should empower people who feel they are genetically susceptible, because it gives them evidence that something can be done about it,” Loos said. “If you have a healthy lifestyle, and if you reduce your consumption of sugar-sweetened beverages, then you can suppress your genetic susceptibility.”

—Staff writer Cynthia W. Shih can be reached at cshih@college.harvard.edu.