Vegetarian diet, physical activity protect against diabetes

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New research shows that following a vegetarian diet and exercising at least three times a week significantly reduced the risk of diabetes in African Americans, who are twice as likely to be diagnosed with diabetes when compared to non-Hispanic whites.

"These findings are encouraging for preventing type 2 diabetes in the black population, which is more susceptible to the disease than other populations," said Serena Tonstad, MD, a professor at Loma Linda University and lead author of the research, published in the October issue of Nutrition, Metabolism & Cardiovascular Diseases.

In addition to being at a greater risk for developing diabetes, black persons in the U.S. are also more likely to suffer from diabetes-related complications, such as end-stage renal disease and lower-extremity amputations, according to the U.S. Department of Health and Human Services.

"A vegetarian diet may be a way to counteract the increased diabetes risk for the black population," Dr. Tonstad said.

Dr. Tonstad's research showed that, compared to non-vegetarian blacks, vegan blacks had a 70 percent reduced risk of diabetes, and lacto-ovo vegetarian blacks (those who consume dairy, but no meat) had a 53 percent reduced risk of diabetes. Dr. Tonstad said one explanation was the protection associated with foods typically consumed in higher amounts in a vegetarian diet. Fruits and vegetables have a high fiber content, which may contribute to a decreased occurrence of type 2 diabetes. In addition, whole grains and legumes (beans) have been shown to improve glycemic control and slow the rate of carbohydrate absorption and the risk of diabetes.

The study also showed that black participants who exercised three or more times a week, compared to once a week or never, had a 35 percent reduced risk of diabetes.

The findings used prospective data (following persons over time) of 7,172 black Seventh-day Adventists participating in Adventist Health Study-2. Adventists are a Protestant religious group that promotes vegetarianism and advocates abstinence from tobacco and alcohol, which results in less confounding (distortions) when studying associations between diet and disease. Participants were given a questionnaire that asked how often they consumed 130 foods and food groups. Participants were then categorized into a dietary category (vegan, lacto-ovo vegetarian, etc.) based on their responses.

The study also analyzed data of 34,215 non-black Adventists and found similar protections against diabetes for a vegetarian diet. These findings confirm results from past cross-sectional research (examining persons at one point in time) that showed a vegetarian diet offered protection against diabetes.