A new study published in the European Association for the Study of Diabetes journal has concluded that plant-based foods lead to a lower risk of developing type 2 diabetes and its prevention. The research, conducted by Professor Frank Hu at the Harvard T.H. Chan School of Public Health in Boston, aimed to identify metabolite profiles related to various plant-based diets and investigate potential links between these profiles and the risk of developing type 2 diabetes.
Experts explained that a metabolite is a substance used or produced during the chemical processes in a living organism, encompassing a large number of compounds found in different foods and a complex variety of molecules formed during the breakdown of these compounds for use by the body. The differences in the chemical composition of foods mean that an individual's diet should reflect within their metabolic profile, and recent technological advancements in high-throughput metabolomics have ushered in a new era of nutritional research. Metabolomics is defined as the comprehensive analysis and identification of all different metabolites present in a biological sample.
Research indicates that the global prevalence of type 2 diabetes in adults has more than tripled in less than two decades, with cases rising from around 150 million in 2000 to over 450 million in 2019, and expected to rise to approximately 700 million by 2045. The global health burden of T2D is growing due to the numerous complications arising from the disease, both macrovascular, such as cardiovascular diseases, and microvascular, affecting the kidneys, eyes, and nervous system.
The diabetes epidemic is primarily driven by unhealthy diets, overweight or obesity, genetic predisposition, and other lifestyle factors such as physical inactivity. The new research linked plant-based diets, particularly those rich in high-quality foods such as whole grains, fruits, and vegetables, to a lower risk of developing T2D.
To understand the underlying mechanisms involved in the new study, the experts analyzed blood plasma samples and dietary intake from 10,684 participants across three prospective groups: the Nurses’ Health Study, Nurses’ Health Study 2, and Health Professionals Follow-up Study. Participants completed food frequency questionnaires, which recorded their adherence to three plant-based dietary patterns: the overall plant-based diet index (PDI), the healthy plant-based diet index (hPDI), and the unhealthy plant-based diet index (uPDI).
The dietary indices were based on individual intake from 18 food groups: healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, tea/coffee), unhealthy plant foods (refined grains, fruit juices, potatoes, sugar-sweetened beverages, and sweets), and animal foods (animal fats, dairy products, eggs, fish, seafood, meats, and assorted animal foods).
The team distinguished between healthy and unhealthy plant foods based on their association with type 2 diabetes, cardiovascular diseases, certain cancers, and other conditions such as obesity and hypertension. Researchers tested blood samples collected in the late 1980s and 1990s in the early stages of the aforementioned three studies to create metabolite profiles for the participants.
The study found that compared to participants who did not develop type 2 diabetes, those diagnosed with the disease during follow-up had lower amounts of healthy plant foods, along with lower scores on PDI and hPDI. Additionally, they had a higher average body mass index, were more likely to suffer from hypertension and high cholesterol levels, used blood pressure and cholesterol medications, and had a family history of diabetes, while being less physically active.
Metabolic data revealed that plant-based diets were associated with multiple unique metabolite profiles, and these patterns differed significantly between healthy and unhealthy plant-based diets. The metabolite data for both the general plant-based diet and the healthy plant-based diet were inversely related to the incidence of type 2 diabetes in the generally healthy population, regardless of body mass index and diabetes risk factors, while no association was observed for unhealthy plant diets. Thus, higher metabolite profile scores for PDI and hPDI indicated closer adherence to these diets and lower risks of developing type 2 diabetes.
Further analysis revealed that after adjusting for levels of trigonelline, hipurate, isoleucine, and a small group of triglycerides (TAGs), along with several other intermediate metabolites, the association between plant-based diets and T2D largely disappeared, indicating these metabolites may play a key role in linking these diets to diabetes. Professor Hu stated, "While it is difficult to draw contributions of individual foods as they were analyzed together as a pattern, individual metabolites from consumption of polyphenol-rich plant foods such as fruits, vegetables, coffee, and legumes are all closely associated with a healthy plant-based diet and reduced diabetes risk."
The authors concluded that their findings support the beneficial role of healthy plant-based diets in diabetes prevention and provide new insights for future investigations.
