New research published in Diabetology (the journal of the European Association for the Study of Diabetes [EASD]) finds that 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 supports their role in preventing diabetes.
The study was conducted by Professor Frank Hu and colleagues from the Department of Nutrition, Harvard TH Chan School of Public Health, Boston, MA, USA, and aimed to identify metabolite profiles related to different diets based on of plants and to study the possible associations between them. 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 large number of compounds found in different foods as well as the complex variety of molecules created when these compounds are broken down and transformed for use by the body. Differences in the chemical composition of foods mean that an individual’s diet should be reflected in their metabolite profile. Recent technological advances in the field of high-throughput metabolomic profiling have ushered in a new era of nutritional research. Metabolomics is defined as the complete analysis and identification of all the different metabolites present in a biological sample.
More than 90% of diabetes cases are type 2 and this condition poses a major health threat worldwide. The global prevalence of the disease 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 reach around 700 million in 2045.
The global health burden of T2D is further compounded by the disease’s many complications, both macrovascular, such as cardiovascular disease, and microvascular, which damage the kidneys, eyes and nervous system. The diabetes epidemic is mainly caused by poor diet, being overweight or obese, genetic predisposition and other lifestyle factors, such as lack of exercise. Plant-based diets, particularly healthy diets high in high-quality foods such as whole grains, fruits, and vegetables, have been associated with a lower risk of developing T2DM, but the underlying mechanisms involved are not fully understood.
The team performed an analysis of blood plasma samples and food intake of 10,684 participants from three prospective cohorts (Nurses’ Health Study, Nurses’ Health Study II, and Healthcare Professionals Follow-Up Study). health). Participants were predominantly white, middle-aged (mean age 54) and with an average body mass index (BMI) of 25.6 kg/m2.
Study participants completed food frequency questionnaires (FFQs) that were scored based on their adherence to three plant-based diets: an overall plant-based diet index (PDI), a plant-based diet index healthy plant-based diet (hPDI) and an unhealthy plant-based diet index. Food-Based Diet Index (uPDI). The diet indices were based on this individual’s consumption of 18 food groups: healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and tea/coffee); unhealthy plant foods (refined cereals, fruit juices, potatoes, sugary drinks and sweets/desserts); and foods of animal origin (animal fats, dairy products, eggs, fish/seafood, meat and various foods of animal origin). The team distinguished between healthy and unhealthy plant foods based on their association with T2D, cardiovascular disease, certain cancers and other conditions, including obesity and high blood pressure.
The researchers tested blood samples taken in the late 1980s and 1990s in the first phase of the three studies mentioned above to create metabolite profile scores for participants, and all cases of incident T2D during the period of study follow-up were recorded. Analyzes of these data along with diet index scores allowed the team to find correlations between metabolite profile, diet index and T2D risk.
The study found that compared to participants who did not develop T2DM, those who were diagnosed with the disease during follow-up had lower intakes of healthy plant-based foods, as well as higher scores. low for PDI and hPDI. Additionally, they had a higher average BMI and were more likely to have high blood pressure and high cholesterol, use blood pressure and cholesterol medications, have a family history of diabetes, and to be less physically active.
Metabolomics data revealed that plant-based diets were associated with unique multi-metabolite profiles and that these patterns differed significantly between healthy and unhealthy plant-based diets. Additionally, metabolite profile scores for whole plant-based diet and healthy plant-based diet were inversely associated with incident T2D in a generally healthy population, independent of BMI and other diabetes risk factors, while no association was observed for unhealthy plant-based diet. Accordingly, higher metabolite profile scores for PDI and hPDI indicated both tighter adherence to these diets and a lower risk of developing T2D.
Further analysis revealed that after adjusting for levels of trigonellin, hippurate, isoleucine, a small set of triacyglycerols (TAGs), and several other intermediate metabolites, the association between diets containing plants and T2DM has largely disappeared, suggesting that they may play a key role in linking these diets to incident diabetes. Trigonellin, for example, is found in coffee and has shown beneficial effects on insulin resistance in animal studies, while higher levels of hippurate are associated with better glycemic control, secretion of improved insulin and lower risk of T2D. The team suggests that these metabolites could be studied further and could provide mechanistic explanations for how plant-based diets may have a beneficial effect on T2DM risk.
Professor Hu explains: “Although it is difficult to disentangle the contributions of individual foods because they were analyzed together as a model, the individual metabolites of the consumption of plant foods rich in polyphenols such as fruits, vegetables , coffee and legumes are all strongly linked to a healthy plant-based diet and a reduced risk of diabetes. »
The authors conclude: “Our results confirm the beneficial role of healthy plant-based diets in the prevention of diabetes and provide new insights for future investigations…our findings regarding intermediate metabolites are intriguing at this time, but further Studies are needed to confirm their causal role in associations of plant-based diets and the risk of developing type 2 diabetes.”
Since they only collected blood samples at one point in time, the authors also believe that repeated long-term metabolomics data are needed to understand how dietary changes relate to changes in the metabolome, thereby influencing the risk of T2D.