To zero in on the power of legumes and pulses (the edible seeds of plants in the legume family), investigators reviewed 73 prospective cohort studies with one year or longer of follow-up that examined the relationship between eating legumes and the incidence of death due to cardiometabolic diseases, diabetes, hypertension, and obesity. Researchers divided the groups into quartiles from highest to lowest consumption of legumes or pulses. Pooled analysis revealed that compared with the people who ate the smallest amount of legumes, people who ate the most legumes and pulses experienced the following benefits:
8 percent decrease in cardiovascular disease10 percent decrease in coronary heart disease9 percent decrease in hypertension13 percent decrease in obesity
People derive two kinds of benefits when they incorporate more legumes into their diet, says John Sievenpiper, MD, PhD, an associate professor in the department of nutrition studies at the University of Toronto and a coauthor of the study. First, there’s the intrinsic value of the beans themselves; the protein, fiber, and micronutrients could all positively contribute to heart health, he says: “Some pulses contain 7S globulins protein, which has been shown in experimental work to reduce cholesterol.” A study published in 2015 in theJournal of Nutritional Science showed that this protein promoted cholesterol-reducing effects in rats. Eating more legumes also has an extrinsic benefit, he says. “Often when people are eating more legumes, it’s displacing red meat, processed meat, and other sources of cholesterol,” he says. That can improve heart health as well, he says. Although these findings aren’t unexpected, this review does a good job of looking at existing research to begin to quantify the health impact of legumes, says Tamanna Singh, MD, a clinical cardiologist at the Cleveland Clinic main campus in Ohio, who was not involved in this research. “Because legumes contain complex carbohydrates, plant-powered protein, and not much fat, it makes sense that consuming more of them would be associated with some reduction in cardiovascular disease, diabetes, or some of those risk factors that are associated with cardiovascular and cerebrovascular disease,” says Dr. Singh.
How Many Servings of Beans Are Necessary for Health Benefits?
Legumes, which are part of the DASH diet and the Mediterranean diet, include soybeans, alfalfa, fresh peas, and green beans. Common pulses are things like lentils, beans, and black-eyed peas, which were named the “legume of the month” by the American Heart Association. These foods can be eaten alone or mixed into salads and soups. You don’t have to eat large quantities of legumes to improve your heart health, says Sievenpiper. “The [U.S. Department of Health & Human Services] considers a half cup of legumes a serving, which would be about 100 grams. Anywhere from a half serving to a full serving per day is where we see the best signal for the associated benefits,” he says. The first step to making dietary shifts is education, says Singh. “Some people are used to eating what they grew up eating, and they aren’t aware of the health benefits of legumes,” she says. Health professionals need to continue to educate the public about the wide variety of plant-based foods and how they compare with animal products, she says. The authors of the study point out that eating more legumes may also have benefits for society as a whole, including “the potential to lower annual healthcare costs and contribute to environmental sustainability, which is a growing global concern.” More research is needed to solidify the ways that legumes impact health, says Singh. “Although it’s difficult to perform dietary studies, randomized controlled studies that do direct comparison of plant-based eating or legume eating versus meat should be pursued,” she says. “This would be very helpful in defining and optimizing our current diet guidelines and would address some current nutritional controversies.”
