Adoption of a plant-based diet, particularly if rich in high-quality foods such as whole grains, fruits, vegetables, nuts, and legumes, substantially reduces the risk of type 2 diabetes, according to a study by the Harvard T.H. Chan School of Public Health published in June 2016 in PLOS Medicine.
According to Ambika Satija, a researcher in the Department of Nutrition and associate author of the study, this research highlights the significant role that even moderate changes in dietary habits toward a healthy plant-based diet can have in preventing type 2 diabetes. These observations provide additional evidence to support current nutritional recommendations in the prevention of this chronic societal disease.
While previous studies have linked vegetarian diets to improved health, including a decreased risk of type 2 diabetes, this new study (1) is the first to distinguish between healthy plant-based diets and others less beneficial to health, including products such as sugary foods and drinks, which can be harmful to health. The study also considered the effect of animal-based foods in the diet.
Study Methodology
The researchers followed over 200,000 men and women healthcare professionals across the United States for more than 20 years, who regularly filled out questionnaires about their diet, lifestyle, medical history, and newly diagnosed illnesses as part of three major long-term studies. The researchers assessed the participants' diets using a dietary index for which they assigned high scores to plant-based foods and lower scores to animal-based foods.
Measured Elements
The study showed that high (but not exclusive) adherence to a plant-based diet and low consumption of animal-based foods was associated with a 20% reduction in the risk of type 2 diabetes compared to low adherence to this diet. Furthermore, a diet based on healthy plant-based foods was linked to a 34% decrease in the risk of diabetes, while a less balanced version - including foods such as refined grains, potatoes, and sugary drinks - was associated with a 16% increase in this risk. Therefore, it is not sufficient to adopt a plant-based diet; it is preferable that this diet consists only of healthy plant-based foods. So forget about fries, potatoes, refined breads and cereals, overly salty or sweet nuts, sugary drinks, etc...
The study also showed that even a modest reduction in the consumption of animal-based foods - for example, from 5/6 servings per day to 4 servings per day - was associated with a lower incidence of diabetes. Animal-based foods include meats and fish, but also seemingly innocuous foods such as dairy products and derivatives, eggs, ham (even lean), and obviously all ready-to-eat products that contain animal-based foods.
Study Conclusions
The researchers suggested that a diet based on healthy plant-based foods reduces the risk of type 2 diabetes because such a diet is inherently rich in fiber, antioxidants, unsaturated fatty acids, and micronutrients such as magnesium, and low in saturated fats. It is also possible that healthy plant foods contribute to the health of the intestinal flora, the implications of which for overall health are being discovered every day. The study's limitations concern possible measurement errors because the information was provided by the participants, but the authors note that the study evaluated the diet cumulatively over time, which reduces errors. The authors also stated that their observations should be replicated in other populations to verify their validity on a broader scale.
Sources : hsph.harvard.edu. Références : (1) Plant-Based Dietary Patterns and Incidence of Type 2 Diabetes in US Men and Women: Results from Three Prospective Cohort Studies