There is abundant research showing that regular bean consumption provides a variety of health benefits. Numerous studies indicate that frequently eating beans as a part of a healthful diet may reduce risk as well as aid in management of many chronic diseases.
What does “regular bean consumption” mean? The U.S. Dietary Guidelines recommends eating about 3 cups of legumes—like pinto, kidney, or black beans—per week. If you eat about ½ cup of beans every day, you’ll meet the weekly Dietary Guidelines for beans.
An individual’s diet has been shown to affect disease susceptibility and survival. Comparing the dietary patterns of older adults is one approach to discovering if there is a common denominator that promotes longevity. In a cross-cultural study looking at food intake patterns of adults 70 years and older, the only statistically significant consistent indicator of longevity was legume intake. (Darmadi-Blackberry, 2004) For every 20 grams of legumes consumed each day, there was a 7-8% reduction in mortality (based on hazard ratios). A half-cup serving of beans weighs about 85 grams, so based on these findings you may reduce your risk of all-cause mortality by 30-34% if you consume a half-cup of beans most days.
BEANS & DIABETES
Diabetes is becoming more common around the world as the overweight and obesity epidemic continues. Eating a variety of legumes, including beans, may be valuable not only in the prevention but also management of diabetes.
Beans are rich in slowly digestible carbohydrates and fiber as well as protein, giving them a low glycemic index. This makes them an ideal food for the management of insulin resistance and diabetes. Beans also provide protein as well as important vitamins and minerals in the diet.
According to the American Diabetes Association, “The glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are those that are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels. Low-GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood sugar and insulin levels, and have proven benefits for health.”
Numerous studies show that consuming a low glycemic load diet may be protective against developing diabetes, while consuming a high glycemic load diet may increase the risk. This makes beans an important food for individuals working to manage blood sugars.
The glycemic load of a food is calculated by taking the glycemic index and multiplying it by the amount of total carbohydrate in a portion of food. Pinto beans cooked from the dry form have a glycemic index of 39, meaning the pinto beans only increase a person’s blood sugar by 39% compared to glucose or white bread. A ½ cup portion of pinto beans contains 22 grams of total carbohydrate, so the glycemic load is approximately 9.
The American Diabetes Association suggests that people with diabetes include dry beans (like kidney or pinto beans) and lentils into meals. The USDA MyPlate also recommends beans as a healthy food choice. The 2010 Dietary Guidelines for Americans recommends eating 3 cups of legumes (including beans) per week. That is equal to approximately ½ cup per day.
BEANS & HEART HEALTH
Beans promote heart health because of what they contain (fiber and potassium) as well as what they don’t contain (no saturated fat, trans fat, cholesterol, or sodium).
Elevated blood levels of triglycerides and cholesterol, especially LDL cholesterol, are significant contributing factors to the risk of heart disease. Legume and dry bean consumption have been shown to improve serum lipid profiles in patients with coronary heart disease (CHD), and research shows that a healthful diet that includes beans may reduce the risk of heart disease.
Therapeutic Lifestyle Changes (TLC) is a program from the National Cholesterol Education Program (NCEP) to help lower cholesterol through lifestyle approaches (National Heart, Lung, and Blood Institute, 2005). As dietary changes are typically the first step in lowering cholesterol, the TLC diet is a great first approach to lower one’s cholesterol.
The TLC diet emphasizes fruits and vegetables, whole grains, lean meats and low-fat dairy. It recommends limiting consumption of saturated and trans fat, and fatty meats. It also includes recommendations for the use of functional foods such as legumes, oats, and margarines containing plant stanols/sterols to lower cholesterol.
The NCEP Adult Treatment Panel III guidelines identify legumes as a good low saturated fat protein source and also recognize their contribution to viscous or soluble fiber intake in the diet (National Cholesterol Education Program, 2002). One-half cup of legumes supplies 5.5 – 8 grams of total fiber including 1 – 3.5 grams of viscous or soluble fiber or 10-35% of the 5 – 10 grams of daily viscous or soluble fiber intake recommended by the NCEP ATP III.
BEANS & CANCER
Research has revealed that a healthful diet including beans may reduce the risk of certain types of cancer. Beans are natural sources of antioxidants and phytochemicals; these compounds work in the body to decrease the risk of cancer, as well as other chronic diseases.
The World Cancer Research Fund/American Institute for Cancer Research (2007) published a comprehensive review that linked diet to cancer at 19 different locations in the body. Considering the cause of cancer at many of the sites, one would expect that diet would have little impact except for excess body fat possibly increasing the risk. Beans were not considered a separate set, but part of a group of foods labeled “pulses (legumes)”. If a food, group of foods, and/or individual nutrient was found to be related to cancer incidence at one of the 19 sites, the relationship was classified as “decreased the risk” or “increased the risk”. The strength of the evidence was classified as “convincing”, “probable”, “limited – suggestive”, or “limited – no conclusion”. To be classified as “probable”, there had to be considerable data demonstrating a relationship existed.
The panel of experts did not feel that the evidence relating legume consumption to a decreased risk of developing cancer was “convincing” or “probable” for cancer located at any of the 19 sites in the body. However, fiber-containing foods were considered “probable” for reducing the risk of cancer in the colon and rectum. Since beans are rich in fiber, it can be inferred that eating beans will probably reduce one’s risk of developing colon and rectal cancer. The data relating legume consumption to a reduction of stomach and prostate cancer was considered “limited, but suggestive”. The link between stomach cancer and legume intake is most likely based on soy and not on legumes other than soy. The study panel concluded that the data suggest that eating non-soy legumes would result in a reduction in prostate cancer. The panel also felt that the data relating foods rich in folate (naturally occurring or fortified) to a reduction in colon and rectal cancer was suggestive, but limited. The data relating legume consumption to cancers of the mouth, pharynx, larynx, esophagus, lung, pancreas, breast, ovary, and endometrium was too limited and no conclusion could be reached.
World Cancer Research Fund/American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington DC: AICR, 2007
Darmadi-Blackberry I, Wahqvist ML, Kouris-Blazos A, et al. Legumes: the most important dietary predictor of survival in older people of different ethnicities. Asia Pacific Journal Of Clinical Nutrition. 2004;13(2):217- 220.
National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III),. Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III), Final Report. Washington, D.C.: National Heart, Lung and Blood Institute of the National Institutes of Health; September 2002. NIH Publication No. 02-5215.