A plant-based diet reduces the risk of diabetes, according to Harvard experts

In America, there are 62 million people living with type 2 diabetes. This number has tripled in the region since 1980 and is estimated to reach the 109 million mark by 2040, according to the Diabetes Atlas. Scientific research runs a race to understand what causes more and more people to be developing that disease that is the result of the ineffective use of insulin by the body.

Now, a study by researchers at Harvard University in the United States has provided more evidence on the mechanisms that make it that if people consume more plant-based foods, such as fruits, vegetables, nuts, coffee and legumes, they are less likely to have diabetes.

The research was published in the journal Diabetologia of the European Association for the Study of Diabetes. It shows that the consumption of healthy plant-based foods, such as fruits, vegetables, nuts, coffee and legumes, is associated with a lower risk of developing type 2 diabetes in generally healthy people and supports their role in preventing diabetes.

The study was led by Professor Frank Hu and his colleagues in the Department of Nutrition at the T.H. Chan School of Public Health at Harvard University, in Boston, USA, and aimed to identify metabolite profiles related to different plant-based diets and investigate possible associations between those profiles and the risk of developing diabetes. Metabolites are substances produced after digestion or other body chemical processes.

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

Differences in the chemical composition of foods cause an individual's diet to be reflected in their metabolite profile. Recent technological advances in the field of high-performance metabolomic profiles have ushered in a new era of nutritional research.

Harvard researchers noted that more than 90% of diabetes cases are type 2, and this disease poses a major health threat worldwide. Because uncontrolled diabetes can cause complications, both macrovascular, cardiovascular, and microvascular, that damage the kidneys, eyes and nervous system.

The diabetes epidemic is mainly caused by unhealthy diets, overweight or obesity, genetic predisposition and other lifestyle factors, such as lack of physical activity. While it was already known that plant-based diets, especially those that are healthy and rich in high-quality foods such as whole grains, fruits and vegetables, have been associated with a lower risk of developing diabetes, the underlying mechanisms involved were not yet clear.

The team performed an analysis of blood plasma samples and dietary intake of 10,684 participants from three prospective cohorts of previous studies. The participants were predominantly white, middle-aged (mean 54 years) and had an average body mass index of 25.6 kg/m2.

Participants in the study completed food frequency questionnaires that were scored according to their adherence to three plant-based diets: a general Plant-Based Diet Index (PDI), a Healthy Plant-Based Diet Index (hPDI) and an Unhealthy Plant-Based Diet Index (UPDi).

Dietary indices were based on the individual intake 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 animal foods).

The team distinguished between healthy and unhealthy plant foods based on their association with diabetes, cardiovascular disease, certain cancers, and other conditions, such as obesity and high blood pressure.

The researchers analyzed blood samples taken in the late 1980s and 1990s at the initial stage of the three studies mentioned above to create metabolite profile scores of participants, and all cases of incident diabetes were recorded during the study follow-up period. The analysis of these data together with the dietary index scores allowed the team to find correlation between the metabolite profile, the diet index and the risk of diabetes.

The study found that, compared to participants who did not develop type 2 diabetes, 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 the diet index based on plants and the index of healthy plant-based diets.

In addition, they had a higher average body mass index and were more likely to have high blood pressure and cholesterol levels, to use medicines for blood pressure and cholesterol, to have a family history of diabetes, and to be less physically active.

In the case of coffee consumption, which was also associated with a lower risk of diabetes, it is known that it has polyphenols. It has a high content of trigonelline, a compound linked to increased insulin sensitivity in some studies. Another compound linked to the consumption of coffee, as well as whole grains and fruit, is called hippurate, and has been linked to increased blood sugar stability.

At the moment, according to the researchers, evidence suggests that the best option for health is to eat many unprocessed plants and reduce processed foods and added sugars, even if they are technically vegetable.

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