Consuming high-quality plant foods such as whole grains, fruits, vegetables, nuts and legumes may substantially lower risk of developing type 2 diabetes, researchers including one of Indian-origin have claimed.

“This study highlights that even moderate dietary changes in the direction of a healthful plant-based diet can play a significant role in the prevention of type 2 diabetes,” said Ambika Satija from Harvard T H Chan School of Public Health in the US.

“These findings provide further evidence to support current dietary recommendations for chronic disease prevention,” she said.

While previous studies have found links between vegetarian diets and improved health outcomes, including reduced risk of type 2 diabetes, this new study is the first to make distinctions between healthy plant-based diets and less healthy ones that include things like sweetened foods and beverages, which may be detrimental for health.

The study also considered the effect of including some animal foods in the diet.

Researchers followed more than 200,000 male and female health professionals in the US for more than 20 years who had regularly filled out questionnaires on their diet, lifestyle, medical history, and new disease diagnoses as part of three large long-term studies.

They evaluated participants’ diets using a plant-based diet index in which they assigned plant-derived foods higher scores and animal-derived foods lower scores.

The study found that high adherence to a plant-based diet that was low in animal foods was associated with a 20 per cent reduced risk of type 2 diabetes compared with low adherence to such a diet, researchers said.

Eating a healthy version of a plant-based diet was linked with a 34 per cent lower diabetes risk, while a less healthy version – including foods such as refined grains, potatoes, and sugar-sweetened beverages – was linked with a 16 per cent increased risk, they said.

Even modestly lowering animal food consumption – for example, from 5-6 servings per day to about 4 servings per day – was linked with lower diabetes incidence, the study found.

“A shift to a dietary pattern higher in healthful plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts, and seeds, and lower in animal-based foods, especially red and processed meats, can confer substantial health benefits in reducing risk of type 2 diabetes,” said Frank Hu from Harvard Chan School.

Researchers suggest that healthful plant-based diets could be lowering type 2 diabetes risk because such diets are high in fiber, antioxidants, unsaturated fatty acids, and micronutrients such as magnesium, and are low in saturated fat. Healthy plant foods may also be contributing to a healthy gut microbiome, they said.

The findings were published in the journal PLOS Medicine.