Good news for vegans: Harvard study says they’re less likely to develop diabetes

By Stephen Beech via SWNS

Vegans are less likely to develop diabetes, according to a new study.

Harvard researchers found that a diet of healthy plant-based foods - including fruits, vegetables, nuts, coffee, and legumes - is associated with a lower risk of developing type 2 diabetes (T2D) in generally healthy people.

The study aimed to identify the metabolite profiles related to different plant-based diets and investigate possible links between those profiles and the risk of developing T2D.

A metabolite is a substance used or produced by the chemical processes in a living organism and includes the vast number of compounds found in different foods as well as the complex variety of molecules created as those compounds are broken down and transformed for use by the body.

Differences in the chemical makeup of foods means that a person’s diet should be reflected in their metabolite profile.

Recent technological advances have ushered in a new era of nutritional research.

The number of people with diabetes has more than tripled worldwide in less than two decades, with cases increasing from around 150 million in 2000 to more than 450 million in 2019 - and is projected to rise to around 700 million in 2045.

The global health burden of T2D is further increased by several complications arising from the disease, including cardiovascular disease plus damage to the kidneys, eyes, and the nervous system.

The diabetes epidemic is primarily caused by unhealthy diets, obesity, genetic predisposition, and other lifestyle factors such as a lack of exercise.

Plant-based diets - especially ones including whole grains, fruit and veg - have been associated with a lower risk of developing T2D, but the underlying mechanisms involved are not fully understood.

The American research team conducted an analysis of blood plasma samples and dietary intake of more than 10,600 participants who were mostly white, middle-aged and overweight.

The participants completed food frequency questionnaires which were scored according to their adherence to three plant-based diets: an overall Plant-based Diet Index (PDI), a healthy Plant-based Diet Index (hPDI), and an Unhealthy Plant-Based Diet Index (uPDI).

The research team distinguished between healthy and unhealthy plant foods according to their association with T2D, cardiovascular disease, certain cancers, and other conditions, including obesity and high blood pressure.

They tested blood samples taken in the late 1980s and 1990s to create metabolite profile scores for the participants, and any cases of incident T2D during the follow-up period of the study were recorded.

Analysis of the data along with the diet index scores enabled the team to find any correlations between metabolite profile, diet index, and T2D risk.

The study found that compared with participants who did not develop T2D, those who were diagnosed with the disease during follow-up had a lower intake of healthy plant-based foods, as well as lower scores for PDI and hPDI.

They also had a higher average BMI, and were more likely to have high blood pressure and cholesterol levels, use blood pressure and cholesterol drugs, have a family history of diabetes, and be less physically active.

The data revealed that plant-based diets were associated with unique multi-metabolite profiles, and that these patterns differed "significantly" between the healthy and unhealthy plant-based diets.

The researchers found that higher metabolite profile scores for PDI and hPDI indicated both closer adherence to those diets and having a lower risk of developing T2D.

Further analysis revealed that after adjusting for levels of trigonelline, hippurate, isoleucine, a small set of triacyglycerols (TAGs), and several other intermediate metabolites, the association between plant-based diets and T2D largely disappeared, suggesting that they might play a key role in linking those diets to incident diabetes.

Study leader Professor Frank Hu, of Harvard T.H. Chan School of Public Health, said: "Trigonelline, for example, is found in coffee and has demonstrated beneficial effects on insulin resistance in animal studies, while higher levels of hippurate are associated with better glycaemic control, enhanced insulin secretion and lower risk of T2D."

The team suggest that the metabolites could be investigated further and may provide explanations of how plant-based diets can reduce the risk of diabetes.

Prof Hu said: “While it is difficult to tease out the contributions of individual foods because they were analyzed together as a pattern, individual metabolites from consumption of polyphenol-rich plant foods like fruits, vegetables, coffee, and legumes are all closely linked to a healthy plant-based diet and lower risk of diabetes.”

“Our findings support the beneficial role of healthy plant-based diets in diabetes prevention and provide new insights for future investigation.

"Our findings regarding the intermediate metabolites are at the moment intriguing, but further studies are needed to confirm their causal role in the associations of plant-based diets and the risk of developing type 2 diabetes.”

The findings were published in Diabetologia, the journal of the European Association for the Study of Diabetes [EASD].