MedWire News: People consuming vegetarian diets have a substantially lower risk for Type 2 diabetes and a lower body mass index than people consuming non-vegetarian diets, shows a cross-sectional study reported in the journal Diabetes Care.
Hypothesizing that vegetarian diets may carry metabolic advantages for preventing diabetes, Serena Tonstad (Loma Linda University, California, USA) and colleagues compared the prevalence of Type 2 diabetes in people following different types of vegetarian diets with that in non-vegetarians.
The study population were Seventh-Day Adventist church members (22,434 men and 38,469 women) participating in the Adventist Health Study-2. The authors collected self-reported demographic, anthropometric, medical history, and lifestyle data.
The type of vegetarian diet was categorized based on a food frequency questionnaire as follows: vegan (no animal products), lacto-ovo vegetarian (including eggs, milk, and milk products), pesco-vegetarian (including fish in addition to lacto-ovo diet), and semi-vegetarian (including dairy products and/or eggs and meat at least once per month, but no more than once a week). Participants were almost exclusively nonsmokers.
Mean body-mass index was lowest in vegans (23.6 kg/m2), followed by lacto-ovo vegetarians (25.7 kg/m2), pesco-vegetarians (26.3 kg/m2), semi-vegetarians (27.3 kg/m2) and non-vegetarians (28.8 kg/m2). Type 2 diabetes was reported in 3430 [MedWire house style] (5.6%) participants.
“The prevalence of Type 2 diabetes increased incrementally among vegans, lacto-ovo vegetarians, pesco-vegetarians, semi-vegetarians, and nonvegetarians,” report the authors.
Specifically, the prevalence was 2.9% in vegans, 3.2% in lacto-ovo vegetarians, 4.8% in pesco-vegetarians, 6.1 % in semi-vegetarians, [NB – US serial comma]and 7.6% in non-vegetarians.
After adjustment for baseline confounding factors, vegan and lacto-ovo vegetarian diets were associated with a nearly one-half reduction in risk for Type 2 diabetes compared with the risk associated with non-vegetarian diets. “Pesco- and semi-vegetarian diets were associated with intermediate risk reductions: between one-third and one-quarter,” the authors add.
They caution that the data are cross-sectional and therefore no causal inferences can be made, but they note that the 5-unit body-mass index difference between vegans and non-vegetarians indicates a substantial potential of vegetarianism to protect against obesity.
“All variants of vegetarian diets (vegan, lacto-ovo, and pesco-, and semi-vegetarian) were associated with substantially lower risk of Type 2 diabetes and lower body mass index than non-vegetarian diets. The protection afforded by vegan and lacto-ovo vegetarian diets was strongest,” the authors conclude.
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