The consumption 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 and support their role in diabetes prevention.
The diabetes epidemic is primarily caused by unhealthy diets, having overweight or obesity, genetic predisposition, and other lifestyle factors such as a lack of exercise.
Plant-based diets, especially healthy ones rich in high quality foods such as whole grains, fruits, and vegetables, have been associated with a lower risk of developing T2D but the underlying mechanisms involved are not fully understood.
The study, published in the journal Diabetologia, found that compared with participants who did not develop T2D, those who were diagnosed with the disease had a lower intake of healthy plant-based foods.
In addition, they had a higher average body mass index, 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.
"Our findings support the beneficial role of healthy plant-based diets in diabetes prevention and provide new insights for future investigation," said Professor Frank Hu at the Department of Nutrition, Harvard T.H. Chan School of Public Health.
For the study, the team conducted an analysis of blood plasma samples and dietary intake of 10,684 participants.
The 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 found 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.
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.
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 these metabolites could be investigated further and may provide mechanistic explanations of how plant-based diets can have a beneficial effect on T2D risk.
Over 90 per cent of diabetes cases are the type 2 form, and the condition poses a major threat to health around the world.
Global prevalence of the disease in adults has more than tripled in less than two decades, with cases increasing from around 150 million in 2000 to over 450 million in 2019 and projected to rise to around 700 million in 2045.