Vegetarian diets, including vegan and lacto-ovo vegetarian regimens, substantially reduce the risk of type 2 diabetes, a new paper by the US Academy of Nutrition and Dietetics suggests.

The organisatio, which represents over 100,000 registered dieticians, has reviewed a number of meta-analyses on the health benefits of plant-based eating for the prevention and management of type 2 diabetes.

It has found that meat eaters had more than twice the prevalence of diabetes compared with lacto-ovo-vegetarians and vegans, although the data behind these findings only corrected for body mass index (BMI) as a cofactor.

The Academy’s paper also elaborates on the odds of developing diabetes with vegetarian and vegan diets. Those risks were reduced by 77 per cent for vegans and by 54 per cent for lacto-ovo-vegetarians.

Once BMI and other confounding factors are accounted for, vegans and lacto-ovo-vegetarians are still respectively 62 per cent and 38 percent less likely to develop type 2 diabetes.

The authors argue that vegetarian diets are protective due to the high intake of fibre and phytochemicals derived from vegetables, fruits, legumes, as well as nuts and seeds.

The authors also point out that certain vegetarian foods, such as legumes, are low-glycemic – which helps reduce blood sugar levels.

Other claims as to why these diets promote better health than alternatives in the paper are based on a small quantity of studies and tend to support recommendations in US dietary guidelines that are based on inconclusive evidence.

These claims include mentions of red and processed meats being strongly associated with increased diabetes risks, which has yet to be established through rigorous analysis of the scientific literature on this subject.

In addition to that, there is omission of crucial evidence when it comes to carbohydrate intolerance and the effects of saturated fat, which suggests reluctance by the Academy to consider any evidence that contradicts official nutritional advice.

For example, the paper puts forward that whole-grain intake has been consistently associated with a lower risk of diabetes, yet the most recent research on conventional high-carbohydrate, low-fat diets does not support this at all.

These past arguments about saturated fat and carbohydrates have been largely debunked since the Academy’s last position statement paper in 2009 and should have been more explicitly reflected in this one.