What are legumes?
Legumes include plant species in the Fabaceae (pea) family. A pulse is the edible seed from a legume plant. Pulses include beans (kidney, black, pinto), lentils (of various colors), and peas (chick peas, green peas).
What the big deal about legumes?
Legumes may lack sex appeal, but they more than make up for this deficiency as a low-cost source of protein, fiber, vitamins, minerals, and micronutrients. The shift in Americans’ diets toward high-calorie, ultra-processed foods has been accompanied by reduced consumption of healthier foods, such as leafy greens and legumes. Plus, legumes provide substantial amounts of relatively low-cost protein, which is especially important for vegetarians, Americans on a limited food budget, and folks in developing countries.
Because legumes can turn atmospheric elemental nitrogen (80 percent of Earth’s atmosphere) into bioavailable nitrogen, farmers often grow legumes to alternate with crops, such as corn, that extract lots of nitrogen from the soil. The nitrogen fixed by legumes can reduce or eliminate the need for artificial forms of bioavailable nitrogen, such as commercial fertilizers. Farmers often grow legume plants to feed livestock (alfalfa hay) or to plow under to improve soil fertility.
Finally, substituting legumes for some of the meat that you would otherwise eat will reduce your ecological footprint with fewer greenhouse gas emissions.
Eat more legumes, reduce your risk of cardiovascular disease
Legumes contain relative large amounts of protein, soluble fiber, and folate, which may reduce blood fats and reduce the risk of coronary heart disease. Researchers used data from 9,632 participants with an average of 50 years at baseline in the National Health and Nutrition Examination Survey to test this idea. Legume intake was evaluated with a 3-month food frequency questionnaire at baseline and grouped in four categories of increasing daily consumption. Compared to participants who ate legumes less than once per week, participants who ate legumes four or more times per week had significant 21 and 9 percent lower risks of developing coronary heart disease and cardiovascular disease, respectively, during 19 years of follow-up. These results accounted for confounding factors such as age, systolic blood pressure, and body-mass index. Thus, more frequent legume intake predicted lower risk of coronary heart disease and cardiovascular disease regardless of cardiovascular disease risk factors. Eat more legumes to reduce your risk of heart disease.
Eat more beans, live longer
A team of researchers investigated links between categories of food consumption in five cohorts of different ethnicities in Japan, Sweden, Greece, and Australia. Food categories included vegetables, legumes, fruits and nuts, cereals, dairy products, meat and meat products, fish and shellfish, alcohol, and the ratio of monounsaturated to saturated fat. Participants included 785 men and women age 70 or older at baseline. The cohorts showed diverging intakes of these food groups. Of the food groups, legume consumption showed the greatest ability to survival. Each 20-gram increase (less than one ounce) in daily legume intake predicted a significant 8 percent decrease in risk of death during up to 7 years of follow-up. To put this result in context, one serving (1/2 cup of dry beans) of pinto beans comprises 35 grams. Thus, cohort members who ate one serving of pinto beans would reduce their risk of mortality by 14 percent. Eat more beans and live longer.
Legumes and diabetes
A recent narrative review of 18 studies included data from participants with or without diabetes. Of five studies that included participants with diabetes, three studies reported significantly reduced levels of fasting blood glucose in response to legume dietary supplementation. However, the quality of the evidence was very low. Legume supplementation did not produce significant reductions in diabetes-related metabolic factors for participants without diabetes. This review provides mild support for persons with diabetes eating legumes to help manage their blood sugar.
Legumes are part of an optimal diet
There’s little doubt that a high-quality diet predicts better health and longer life. General agreement exists regarding which foods predict longer or shorter life expectancy. Norwegian researchers used meta-analyses and data from the 2019 Global Burden of Disease study to estimate the increase in life expectancy associated with an optimal diet, a feasibility diet, and a typical Western diet. The respective diets included varying amounts of whole grains, fruits, vegetables, whole grains, nuts, legumes, fish, eggs, milk/daily, red meat, processed meat, and sugar-sweetened drinks. The optimal diet included one cup of soaked (then cooked) beans each day. The researchers assumed a 10-year time to capture the long-term effect of the improved diets.
Twenty-year old American men and women who eat the optimal diet were estimated to live an extra 13 and 10.7 years, respectively, compared to those who ate a typical Western diet. Read that again! Even 80-year old Americans of either sex would live an extra 3.4 years. Dietary items of the optimal diet that contribute the most to extend longevity include legumes, whole grains, and nuts, in part because most Americans eat so little of these foods. Reducing consumption of red and processed meats would also make substantial contributions to increased life expectancy. How about finding delightful ways to eat more red lentils, which are high in protein and dietary fiber plus they’re inexpensive. I recommend lentil soup—see the recipe below.
Does everybody understand the health benefits of legumes?
Abundant research documents the health value of beans. But has this research trickled down to older people whose diet would improve by eating more beans? Researchers in Canada addressed this question with data from 250 community-dwelling adults over age 65 living in and near Guelph, Ontario. Participants filled out a questionnaire that inquired about the respondents’ beliefs about the nutritional aspects of beans and their role in healthy living. After the questionnaires were analyzed, participants were assigned to one of 10 focus groups with 4-6 persons in each. Questions posed in the focus groups inquired about the health values of beans and their consumption by participants.
Generally, bean consumers were more likely than non-consumers to correctly identify beans as good sources of fiber with low levels of saturated fat, trans fat, and cholesterol. In addition, bean consumers were more likely to believe that beans help with body weight management and reduce constipation. Participants identified barriers to bean consumption including not thinking of beans when planning meals, increased risk of flatulence, and lack of knowledge about preparing beans. This study suggests beans are not top-of-mind for many people, in spite of beans’ health value. Carefully designed and targeted public health messages may be one way to increase public awareness of the nutritional value of beans and how to prepare them.
Lentil soup
My wife, Betsy, eat lentil soup for dinner frequently during the cooler months of the year. It’s easy and inexpensive to make, tastes great, and is highly nutritious. Here’s a recipe that I think you’ll like. Give it a try!
