Type 2 diabetes is a global health concern. More than 90% of all diabetes cases around the world fall into the type 2 category, with global prevalence having tripled over the last 20 years.
In 2000, around 150m people had type 2 diabetes. By 2045, it is estimated this figure will have risen to 700m.
Plant-based diets, notably those rich in whole grains, fruit, and vegetables, have been associated with a lower risk of type 2 diabetes. However, until now, that association has not been fully understood.
Researchers haven’t known whether plasma metabolite profiles related to plant-based diets reflect this association or not.
A metabolite is a substance used or produced by the chemical process 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 an individual’s diet should be reflected in their metabolic profile.
In a new study published in EASD journal Diabetologia, researchers from Harvard University’s Department of Nutrition, have sought to identify the plasma metabolite profiles related to plant-based diets, and evaluate the associations between the identified metabolite profiles and risk of type 2 diabetes.
To do so, the team conducted an analysis of blood plasma samples and dietary intake of 10,684 participants from three prospective cohorts. They were asked to complete food frequency questionnaires, which were scored according to their adherence to three plant-based diets: an overall plant-based diet index, a healthy plant-based diet index, and an unhealthy plant-based diet index.
Whether a diet was classified as healthy or unhealthy depended on foods’ association with type 2 diabetes, cardiovascular disease, certain cancers, and other conditions, including obesity and high blood sugar.
‘Healthy’ foods, for example, included whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and tea/coffee. ‘Unhealthy’ foods included refined grains, fruit juices, potatoes, sugar-sweetened beverages, and sweets/desserts.
Blood samples taken in the early phase of the three studies were analysed to compare with any cases of type 2 diabetes identified during the follow-up period.
The researchers found that those diagnosed with type 2 diabetes during the follow-up had a lower intake of healthy plant-based foods, compared to those who did not develop the disease. They also had a higher average BMI, and were more likely to have high blood pressure and cholesterol levels, have a family history of diabetes, and be less physically active.
Metabolic profiles differed significantly between the healthy and unhealthy plant-based diets, with metabolic profile scores for ‘overall plant-based’ diet and ‘healthy plant-based’ diet both being inversely associated with incident type 2 diabetes in a generally healthy population.
No association was observed for the unhealthy plant-based diet.
“While it is difficult to tease out the contributions of individual foods because they were analysed together as a pattern, individual metabolites from consumption of polyphenol-rich plant foods like fruits, vegetables, coffee, and legumes are all closely linked to healthy plant-based diet and lower risk of diabetes,” noted Professor Frank Hu from Harvard University’s T.H. Chan School of Public Health.
In conclusion, the study authors noted that their 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.”
Specifically, the researchers believe that long-term repeated metabolomics data would help to better understand how dietary changes relate to changes in metabolome, thereby influencing type 2 diabetes risk.
‘Plasma metabolite profiles related to plant-based diets and the risk of type 2 diabetes’
Published 8 April 2022
Authors: Fenglei Wang, Megu Y Baden, Marta Guasch-Ferré, Clemens Wittenbecher, Jun Li, Yanping Li, Yi Wan, Shilpa N Bhupathiraju, Deirdre K Tobias, Clary B Clish, Lorelei A Mucci, A Heather Eliassen, Karen H Costenbader, Elizabeth W Karlson, Alberto Ascherio, Eric B Rimm, JoAnn E Manson, Liming Liang, Frank B Hu.