Vegan diet may prevent type 2 diabetes

New research suggests that even a short-term vegan diet can boost the gut microbes that are related to improvements in body weight, body composition and blood glucose management. Gut microbiota play an important role in weight regulation, the development of metabolic syndrome and type 2 diabetes. Researchers tested the effect of a 16-week plant-based diet on gut microbiota composition, body weight, body composition, and insulin resistance in overweight adults with no history of diabetes. Results showed significant reduction in body weight in the vegan group, particularly due to a reduction in fat mass and in visceral fat.  Insulin sensitivity also increased significantly in the vegan group.

The research was presented at this year’s Annual Meeting of the European Association for the Study of Diabetes (EASD) in Barcelona, Spain (16-20 September). The study is by Dr Hana Kahleova, Physicians Committee for Responsible Medicine (PCRM), Washington, DC, USA, and colleagues. The study can be found here: Fat Quantity and Quality, as Part of a Low-Fat, Vegan Diet, Are Associated with Changes in Body Composition, Insulin Resistance, and Insulin Secretion. A 16-Week Randomized Controlled Trial.

The study included 147 participants (86% women and 14% men; mean age was 55.6±11.3 years), who were randomised to follow a low-fat vegan diet (n=73) or to make no changes to their diet (n=74) for 16 weeks. At baseline and 16 weeks, gut microbiota composition was assessed, using uBiome kits. Dual energy X-ray absorptiometry was used to measure body composition. A standard method called the PREDIM index was used to assess insulin sensitivity.

The authors acknowledge that further work is needed to separate out the effects of the vegan diet itself from that of the reduced calories.

“A plant-based diet has been shown to be effective in weight management, and in diabetes prevention and treatment. This study has explored the link between changes in the gut microbiome, and changes in body weight, body composition, and insulin sensitivity. We have demonstrated that a plant-based diet elicited changes in gut microbiome that were associated with weight loss, reduction in fat mass and visceral fat volume, and increase in insulin sensitivity.”

Fibre in food may play the biggest role. The main shift in the gut microbiome composition was due to an increased relative content of short-chain fatty acid producing bacteria that feed on fibre. “High dietary fibre content seems to be essential for the changes observed in our study, “ said the authors.  They plan to compare the effects of a vegan and a standard portion-controlled diet on gut microbiome in people with type 2 diabetes, in order to separate out the positive effects of the reduced calories from those caused by the vegan composition of the diet. “Eating more fibre is the number one dietary recommendation for a healthy gut microbiome,” they said.

The study group plans to collect more data to confirm the role of veganism as a prevention strategy at the 2020 EASD meeting in Vienna, Austria.