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Vegetarian diets show potential for boosting insulin sensitivity

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February 7, 2019

Vegetarian dietary patterns, especially vegan diets, may improve insulin sensitivity and beta-cell function in adults compared with those who eat meat, according to findings published in Nutrition, Metabolism and Cardiovascular Diseases.

“It has been suggested that vegetarian diet may have a potential protective effect on the prevention and treatment of diabetes and its complications,” Xiuhua Shen, MD, PhD, of the department of nutrition in the School of Public Health at Shanghai Jiao Tong University in Shanghai, and colleagues wrote. “However, whether the higher insulin sensitivity status in vegetarians is accounted for by weight loss remains unclear and controversial.”

A total of 279 vegetarians and 279 sex- and age-matched omnivores were recruited for a cross-sectional study conducted by Shen and colleagues at Xinhua Hospital in Shanghai from March to May 2016. In-person interviews determined dietary patterns and vegetarian status. A person was considered a vegetarian if he or she ate only vegetarian meals for at least 1 year. This group was further divided by vegan diet (n = 73; mean age, 34 years; 74% women), which included no animal products, and lacto-ovo-vegetarian diet (n = 206; mean age, 32.5 years; 85.4% women), which included the consumption of eggs and dairy products.

Fasting blood samples were taken to assess glucose and insulin concentrations. The researchers used the homeostasis model assessment to measure insulin sensitivity and beta-cell function.

The average BMI of participants in the vegetarian group was lower than that of the omnivore group (P < .05), whereas the proportion of obesity was 10.4% lower for vegetarians compared with omnivores (P < .05). Vegetarians also had a 1.4% proportion of insulin resistance compared with a 4.7% proportion in omnivores (P < .05), the researchers reported.

When adjusting only for BMI, the researchers found a negative association between vegan diet and fasting blood glucose (beta = –0.03; 95% CI, –0.05 to –0.01), fasting insulin (beta = –0.23; 95% CI, –0.34 to –0.11) and insulin resistance (beta = –0.25; 95% CI, –0.38 to –0.14). A negative association was also found between lacto-ovo-vegetarian diet and fasting blood glucose (beta = –0.03; 95% CI, –0.04 to –0.02) and insulin resistance (beta = –0.1; 95% CI, –0.18 to –0.01) in the entire vegetarian cohort. However, only participants with a vegan diet retained the negative association with fasting insulin (beta = –0.16; 95% CI, –0.3 to –0.01) and insulin resistance (beta = –0.17; 95% CI, –0.32 to –0.03) after adjusting for BMI, vegetarian duration, income, alcohol consumption, daily dietary intake, physical activity, sedentary time and visceral fat area.

“A plant-based diet with a variety of foods rich in phytochemicals and antioxidants, which may have a direct effect on alleviating inflammation and oxidative stress, may account for the higher insulin sensitivity in vegetarians, and especially vegans,” the researchers wrote. “Vegetarians, especially vegans, may be in a healthier insulin sensitivity status than omnivores, which is not completely accounted for by the difference of BMI.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.