Benefits of Beans

By Paul E. Lemanski, MD, MS, FACP

Editor’s Note: This is the 116th in a series on optimal diet and lifestyle to help prevent and treat disease. Any planned change in diet, exercise or treatment should be discussed with and approved by your personal physician before implementation. The help of a registered dietitian in the implementation of dietary changes is strongly recommended.

Medicines are a mainstay of American life and the healthcare system not only because they are perceived to work by the individuals taking them, but also because their benefit may be shown by the objective assessment of scientific study. Clinical research trials have shown that some of the medicines of Western science may reduce the risk of type 2 diabetes, heart attacks, strokes and cardiovascular death, as well as certain cancers.

In the first 115 installments of the Non-Medicated Life, certain dietary practices and a healthy lifestyle have been shown to accomplish naturally for most individuals many of the benefits of medications in the prevention and treatment of chronic medical conditions. This is especially true for the consumption of all legumes, including beans, chickpeas, split peas, and lentils. Indeed, beans can be shown to not only be profoundly good for your heart (and vascular system), but also for cancer prevention and lifespan as well.

What makes beans so health promoting? Let’s start with the composition. Beans contain proteins, carbohydrates, fiber, tiny amounts of fat, as well as iron, zinc, folate and potassium. The amino acid composition of the proteins in beans differs from bean to bean. Soybeans, for example, have a near perfect amino acid balance and are considered a complete protein for the human body’s growth, maintenance and repair. Other beans have less of certain amino acids and thus may require combination with the amino acids in whole grains to achieve perfect protein amino acid composition.

Low levels of certain amino acids, however, are not necessarily detrimental to health. Beans have a lower methionine (a type of amino acid) content as compared to animal protein and this correlates with a longer lifespan in multiple species, including humans. This may be a result of methionine’s pro-oxidant effect. For example, minimizing methionine reduces markers of inflammation in mice, improves stress resistance, and reduces mitochondrial (mitochondria are the power generating structures in all cells) free radical formation and oxidation induced damage to mitochondrial DNA. Indeed, such oxidative damage to mitochondrial DNA is thought to be a major cause for the process of aging.

The carbohydrates and fiber (fiber is a type of non-metabolizable carbohydrate) in beans promote health in multiple ways. Fiber slows the absorption of carbohydrates resulting in a reduction in the rate of rise of blood glucose with a resultant reduction in insulin secretion. Repeated abrupt secretion of insulin from the pancreas as well as increased overall production of insulin because it works less well in lowering blood glucose (insulin resistance) contributes to the development of type 2 diabetes. Moreover, the prebiotic fiber found in lentils and chickpeas feeds the bacteria in your gut (microbiome); these bacteria in turn secrete substances back into the blood stream that slows gastric emptying and slows the rate carbohydrates are absorbed at a subsequent meal – the so called “second  meal effect.”

Beans (as well as whole grains) have carbohydrates and fiber in the proper ratio for human health. Eating diets high in carbohydrates and low in fiber (the usual composition of refined food products) is NOT the unrefined diet our ancestors ate. Over many thousands of years humans became biochemically adapted to whole foods containing the ratio of carbohydrates to fiber such as found in beans. We have inherited that biochemistry, and therefore our bodies function optimally only when given the fuel they were “designed” to use. Indeed, the consumption of beans, nutrient rich and low in calories, has been associated with lower body weights, lower blood pressure, improved blood sugar and insulin levels, and may help reduce the risk for conditions as diverse as stroke, depression and colon cancer.

Beans are naturally low in fat and contain NO cholesterol and consuming them may help lower the LDL or the “bad” cholesterol. Lowering cholesterol naturally will lower the risk for heart attacks and strokes. Moreover, soybeans contain isoflavones, plant-based, naturally occurring estrogen-like molecules that appear to lower the risk for both breast cancer and prostate cancer. In the case of breast cancer isoflavones appear to fit into the estrogen receptor on breast cells, effectively blocking the receptor from accepting an actual estrogen molecule. Breast cancer is most associated with long term, more continuous than not, estrogen stimulation. Risk for breast cancer is highest in women with an early menarche and late menopause and fewer pregnancies to interrupt estrogen’s stimulatory effect. It is felt that the lower rates of breast cancer seen in Asian countries that consume more soy may be due to this special property of soybeans.

If beans are so healthy, then why do most Americans consume so little? A major reason is that beans produce flatulence. This is because some of the fiber in beans is metabolized by the microbiome producing gas. A few practices, however, can minimize this apparent drawback. Lentils, split peas and canned beans produce less gas. Soaking beans overnight before cooking may also reduce gas formation. Finally, slowly increasing the number of beans consumed will minimize flatulence. Start with a teaspoon of lentils on your salad and increase by a teaspoon per week. After 4-5 weeks the lentils should be tolerated without excessive gas formation. Products such as Beano – that contain an enzyme that will break down the gas producing fiber before the microbiome metabolizes it – may also be helpful in the short run.

In summary, beans are some of the healthiest foods that humans can eat. They are high in protein (and low in methionine), low in calories and low in fat. They are an inexpensive source of protein compared to animal derived protein. They are nutrient dense with zinc, folate, potassium, and fiber. Beans are associated with lower rates of obesity, high blood pressure, elevated blood sugar, type 2 diabetes, elevated cholesterol, heart disease, and stroke. They are also associated with lower risk of cancers including the breast, and prostate, and have been one of the most important predictors of survival to old age. As such, the consumption of beans is a useful lifestyle tool in those considering a non-medicated life.

Paul E. Lemanski, MD, MS, FACP (plemanski3@gmail.com) is a board-certified internist practicing internal medicine and lifestyle medicine in Albany. Paul has a master’s degree in human nutrition, he’s an assistant clinical professor of medicine at Albany Medical College, and a fellow of the American College of Physicians.