Legumes may lower risk of type 2 diabetes

New research shows that a high consumption of legumes significantly reduces the risk of developing type 2 diabetes.

The legume family consists of plants such as alfalfa, clover, peas, peanuts, soybeans, chickpeas, lentils, and various types of beans.

As a food group, they are believed to be particularly nutritious and healthful. One of the reasons for this is that they contain a high level of B vitamins, which help the body to make energy and regulate its metabolism. Additionally, legumes are high in fiber and contain minerals such as calcium, magnesium, and potassium. They also comprise a variety of so-called phytochemicals - bioactive compounds that further improve the body's metabolism and have been suggested to protect against heart disease and diabetes.

Finally, legumes are also considered to be a "low glycemic index food," which means that blood sugar levels increase very slowly after they are consumed.

To make people aware of the many health benefits of legumes, the year 2016 has been declared the International Year of Pulses by the Food and Agriculture Organization of the United Nations. Pulses are a subgroup of legumes.

Because of their various health benefits, it has been suggested that legumes protect against the onset of type 2 diabetes. However, little research has been carried out to test this hypothesis.

Therefore, researchers from the Unit of Human Nutrition at the Universitat Rovira i Virgili in Tarragona, Spain, together with other investigators from the Prevención con Dieta Mediterránea (PREDIMED) study, set out to investigate the association between legume consumption and the risk of developing type 2 diabetes in people at an increased risk of cardiovascular disease.

The study also analyzes the effects of substituting legumes with other foods rich in proteins and carbohydrates, and the findings were published in the journal Clinical Nutrition.

High intake of lentils lowers risk of type 2 diabetes by 33 percent

The team investigated 3,349 participants in the PREDIMED study who did not have type 2 diabetes at the beginning of the study. The researchers collected information on their diets at the start of the study and every year throughout the median follow-up period of 4.3 years. Individuals with a lower cumulative consumption of legumes had approximately 1.5 weekly servings of 60 grams of raw legumes, or 12.73 grams per day. A higher legume consumption was defined as 28.75 daily grams of legumes, or the equivalent of 3.35 servings per week.

Using Cox regression models, the researchers analyzed the association between the incidence of type 2 diabetes and the average consumption of legumes such as lentils, chickpeas, dry beans, and fresh peas.

Overall, during the follow-up period, the team identified 266 new cases of type 2 diabetes.

The study revealed that those with a higher intake of legumes were 35 percent less likely to develop type 2 diabetes than their counterparts who consumed a smaller amount of legumes. Of all the legumes studied, lentils had the strongest association with a low risk of type 2 diabetes.

In fact, individuals with a high consumption of lentils (defined as almost one weekly serving) were 33 percent less likely to develop diabetes compared with their low-consumption counterparts - that is, the participants who had less than half a serving per week.

Additionally, the researchers found that replacing half a serving per day of legumes with an equivalent portion of protein- and carbohydrate-rich foods including bread, eggs, rice, or potatoes also correlated with a reduced risk of diabetes.

The authors conclude that: "A frequent consumption of legumes, particularly lentils, in the context of a Mediterranean diet, may provide benefits on type 2 diabetes prevention in older adults at high cardiovascular risk."