Data was collected from 9 observational studies that indicated adherence to a plant based diet was associated with a 23% reduced risk for development of type 2 diabetes, according to the review from Harvard T.H. Chan School of Public Health.
A modest heterogeneity was reported among the studies in the meta analysis, which also found similar outcomes when using fixed effects models for computing relative risk. Those with stricter and healthier definitions of plant based diets to only include fruits, vegetables, whole grains, nuts, and legumes had a point estimate reduction for diabetes risk that was somewhat greater.
“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 lead author Frank Qian, MPH.
“…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,” says senior author Qi Sun.
Major databases were scanned for studies addressing links between plant based diets and incidence of type 2 diabetes in adults including vegan, vegetarian, and other diets low in animal based foods; the loose definition also included sugars, refined sugars, and sweetened beverages.
9 cohorts from 7 published studies were included in the meta analysis that involved data on over 307,000 adults and 23,544 cases of incident of type 2 diabetes; follow up periods ranged from 2 to 28 years and mean baseline BMIs were 23-26.7.
A subgroup analysis between a plant based diet and relative risk reduction in incident of type 2 diabetes was still found; significant diabetes risk reduction was found when the pooled cohort was stratified by age: 55+, 55-, and by gender.
When broken by global region high adherence to a plant based diet was associated with a reduced risk for developing diabetes: North America with a RR of 0.78, Europe with a RR of 0.82, and Asia with a RR of 0.82.
Mechanism most likely behind the association is that components of the plant based diet improves insulin sensitivity, reduces inflammation, improves blood pressure, and helps to maintain a healthy weight, according to the researchers.
“Moreover, plant-based diets may also improve the profile of adiposity-related risk markers, including leptin, adiponectin, high sensitivity C-reactive protein, and interleukin-6,” they added.
Animal products don’t have to necessarily be removed from the diet completely to enjoy similar benefits, according to the researchers, as findings are broadly consistent with association seen with “several other dietary patterns that also emphasize plant-based foods but do not completely exclude animal foods, including the Mediterranean dietary pattern, the Dietary Approaches to Stop Hypertension (DASH) pattern, and the Alternative Healthy Eating Index,” they wrote.
Limitations of the study include it being an observational meta analysis, the lack of randomized clinical trials, and reliance on studies using self reporting diet data and food frequency questionnaires.
