Type 2 diabetes risk could be decreased by following plant-based diets with greater adherence and the risk is less among people whose diets emphasized healthy plant-based foods, according to a new meta-analysis from Harvard T.H. Chan School of Public Health.
The study will be published online in JAMA Internal Medicine.
"Plant-based dietary patterns are gaining popularity in recent years, so we thought it was crucial to quantify their overall association with diabetes risk, particularly since these diets can vary substantially in terms of their food composition," said first author Frank Qian, who conducted the research as a masters student in the Department of Nutrition.
The researchers identified nine studies that looked at this association and were published through February 2019. Their meta-analysis included health data from 307,099 participants with 23,544 cases of type 2 diabetes. They analyzed adherence to an "overall" predominantly plant-based diet, which could include a mix of healthy plant-based foods such as fruits, vegetables, whole grains, nuts, and legumes, but also less healthy plant-based foods such as potatoes, white flour, and sugar, and modest amounts of animal products. The researchers also looked at "healthful" plant-based diets, which were defined as those emphasizing healthy plant-based foods, with lower consumption of unhealthy plant-based foods.
The researchers found that people with the highest adherence to overall predominantly plant-based diets had a 23% lower risk of type 2 diabetes compared to those with weaker adherence to the diets. They also found that the association was strengthened for those who ate healthful plant-based diets.
One mechanism that may explain the association between predominantly plant-based diets and reduced type 2 diabetes risk, according to the researchers, is that healthy plant-based foods have been shown to individually and jointly improve insulin sensitivity and blood pressure, reduce weight gain, and alleviate systemic inflammation, all of which can contribute to diabetes risk.
"Overall, these data highlighted the importance of adhering to plant-based diets to achieve or maintain good health, and people should choose fresh fruits and vegetables, whole grains, tofu, and other healthy plant foods as the cornerstone of such diets," said senior author Qi Sun, associate professor in the Department of Nutrition.