Kidney beans

Health benefits

Kidney beans are a concentrated source of both soluble and insoluble fiber (11.33 g per cup), which helps lower cholesterol by binding bile acids in the digestive tract. Their high fiber content also slows post-meal blood sugar spikes, making them particularly useful for individuals managing diabetes, insulin resistance, or hypoglycemia. When combined with whole grains such as rice, kidney beans provide virtually fat-free complete protein. One cup of cooked kidney beans provides 132.75 mcg of molybdenum (295% DV), an integral component of the enzyme sulfite oxidase, which detoxifies sulfites. Sulfites are preservatives commonly added to prepared foods like delicatessen salads. Persons sensitive to sulfites may experience rapid heartbeat, headache, or disorientation after inadvertent consumption.

A fiber all star

Check a chart of the fiber content in foods and you’ll see legumes leading the pack. Kidney beans, like other beans, are rich in soluble and insoluble fiber. Soluble fiber forms a gel-like substance in the digestive tract that binds with bile (which contains cholesterol)and ferries it out of the body. Research studies have shown that insoluble fiber not only helps to increase stool bulk and prevent constipation, but also helps prevent digestive disorders like irritable bowel syndrome and diverticulosis.

Lower your heart attack risk

In a study that examined food intake patterns and risk of death from coronary heart disease, researchers followed more than 16,000 middle-aged men in the U.S., Finland, The Netherlands, Italy, former Yugoslavia, Greece and Japan for 25 years. Typical food patterns were: higher consumption of dairy products in Northern Europe; higher consumption of meat in the U.S.; higher consumption of vegetables, legumes, fish, and wine in Southern Europe; and higher consumption of cereals, soy products, and fish in Japan. When researchers analyzed this data in relation to the risk of death from heart disease, they found that higher legume consumption was associated with a whopping 82% reduction in risk!

A study published in the Archives of Internal Medicine confirms that eating high fiber foods, such as kidney beans, helps prevent heart disease. Almost 10,000 American adults participated in this study and were followed for 19 years. People eating the most fiber, 21 grams per day, had 12% less coronary heart disease (CHD) and 11% less cardiovascular disease (CVD) compared to those eating the least, 5 grams daily. Those eating the most water-soluble dietary fiber fared even better with a 15% reduction in risk of CHD and a 10% risk reduction in CVD.

Kidney beans’ contribution to heart health lies not just in their fiber, but in the significant amounts of folate and magnesium these beans supply. Folate helps lower levels of homocysteine, an amino acid that is an intermediate product in an important metabolic process called the methylation cycle. Elevated blood levels of homocysteine are an independent risk factor for heart attack, stroke, or peripheral vascular disease, and are found in between 20-40% of patients with heart disease. It has been estimated that consumption of 100% of the daily value (DV) of folate would, by itself, reduce the number of heart attacks suffered by Americans each year by 10%. Kidney beans are a very good source of folate.

Kidney beans also supply magnesium (74.34 mg per cup, 19% DV), which functions as a physiological calcium channel blocker. Adequate magnesium promotes vascular smooth muscle relaxation, reducing peripheral resistance and improving blood flow. Magnesium deficiency is associated with increased risk of myocardial infarction, and insufficient magnesium immediately following a heart attack promotes free radical injury to cardiac tissue.

Kidney beans give you energy to burn while stabilizing blood sugar

In addition to its beneficial effects on the digestive system and the heart, soluble fiber helps stabilize blood sugar levels. If you have insulin resistance, hypoglycemia or diabetes, kidney beans can really help you balance blood sugar levels while providing steady, slow-burning energy. Studies of high fiber diets and blood sugar levels have shown the dramatic benefits provided by these high fiber foods. Researchers compared two groups of people with type 2 diabetes who were fed different amounts of high fiber foods. One group ate the standard American Diabetic diet, which contained 24 grams of fiber/day, while the other group ate a diet containing 50 grams of fiber/day. Those who ate the diet higher in fiber had lower levels of both plasma glucose (blood sugar) and insulin (the hormone that helps blood sugar get into cells). The high fiber group also reduced their total cholesterol by nearly 7%, their triglyceride levels by 10.2% and their VLDL (Very Low Density Lipoprotein,the most dangerous form of cholesterol) levels by 12.5%.

Iron for energy

Kidney beans provide 3.93 mg of non-heme iron per cup (22% DV). Iron is an integral component of hemoglobin, which transports oxygen from the lungs to all body cells, and also functions in key enzyme systems for energy production. Menstruating women face higher risk of iron deficiency, and kidney beans offer a low-calorie, virtually fat-free plant source of this mineral. Iron requirements also increase during pregnancy, lactation, and adolescent growth.

Maintain your memory with thiamin (vitamin B1)

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Manganese for energy production and antioxidant defense

Kidney beans are a good source of the trace mineral manganese which is an essential cofactor in a number of enzymes important in energy production and antioxidant defenses. For example, the key oxidative enzyme superoxide dismutase, which disarms free radicals produced within the mitochondria (the energy production factories within our cells), requires manganese.

Protein power plus

As a plant-based protein source, kidney beans provide over 15 g of protein per cup. Combined with a whole grain such as brown rice or whole wheat pasta, they supply a complete amino acid profile comparable to that of meat or dairy, without the saturated fat. The soluble fiber consumed alongside this protein further supports blood sugar regulation and cardiovascular function.

Description

Just as its name suggests, the kidney bean is shaped like a kidney. Since these dark red beans hold their shape really well during cooking and readily absorb surrounding flavors, they are a favorite bean to use in simmered dishes. Kidney beans that are white in color are known as cannellini beans.

History

Kidney beans and other beans such as pinto beans, navy beans and black beans are known scientifically as Phaseolus vulgaris. They are referred to as “common beans” probably owing to the fact that they all derived from a common bean ancestor that originated in Peru.

They spread throughout South and Central America as a result of migrating Indian traders who brought kidney beans with them from Peru. Beans were introduced into Europe in the 15th century by Spanish explorers returning from their voyages to the New World.

Subsequently, Spanish and Portuguese traders introduced kidney beans into Africa and Asia. As beans are a very inexpensive form of good protein, they have become popular in many cultures throughout the world. Today, the largest commercial producers of dried common beans are India, China, Indonesia, Brazil and the United States.

How to select and store

Dried kidney beans are generally available in prepackaged containers as well as bulk bins. Just as with any other food that you purchase in the bulk section, make sure the bins are covered and that the store has a good product turnover rate.

Whether purchasing kidney beans in bulk or in a packaged container, make sure there is no evidence of moisture or insect damage and that the beans are whole and not cracked.

Canned kidney beans can be found in most markets. Unlike canned vegetables, which have lost much of their nutritional value, there is little difference in the nutritional value of canned kidney beans and those you cook yourself. Canning lowers vegetables’ nutritional value since they are best lightly cooked for a short period of time, while their canning process requires a long cooking time at high temperatures. On the other hand, beans require a long time to cook whether they are canned or you cook them yourself. Therefore, if enjoying canned beans is more convenient for you, by all means go ahead and enjoy them. We would suggest looking for those that do not contain extra salt or additives. (One concern about canned foods is the potential for the can to include a liner made from bisphenol A/BPA. To learn more about reducing your exposure to this compound, please read our write-up on the subject).

Store dried kidney beans in an airtight container in a cool, dry and dark place where they will keep for up to 12 months.

Cooked kidney beans will keep fresh in the refrigerator for about three days if placed in a covered container.

Tips for preparing and cooking

Preparation

Before washing kidney beans, spread them out on a light colored plate or cooking surface to check for and remove stones and damaged beans. After this process, place the beans in a strainer and rinse them thoroughly under cool running water.

To shorten their cooking time and make them easier to digest, kidney beans should be presoaked (presoaking has been found to reduce the raffinose-type oligosaccharides, sugars associated with causing flatulence.) There are two basic methods for presoaking. For each, start by placing the beans in a saucepan with two to three cups of water per cup of beans.

The first method is to boil the beans for two minutes, take pan off the heat, cover and allow to stand for two hours. The alternative method is to simply soak the beans in water for eight hours or overnight, placing the pan in the refrigerator, so the beans will not ferment.

Before cooking the beans, regardless of pre-soaking method, drain the soaking liquid and rinse the beans with clean water.

The healthiest way of cooking kidney beans

To cook the beans, you can either cook them on the stovetop or use a pressure cooker. For the stovetop method, add three cups of fresh water or broth for each cup of dried beans. The liquid should be about one to two inches above the top of the beans. Bring the beans to a boil and then reduce to a simmer, partially covering the pot. If any foam develops, simply skim it off during the simmering process.

Kidney beans generally take about one and one-half hours to become tender using this method. They can also be cooked in a pressure cooker where they take about one-half hour to prepare. Regardless of cooking method, do not add any seasonings that are salty or acidic until after the beans have been cooked. Adding them earlier will make the beans tough and greatly increase the cooking time.

How to enjoy

Serving ideas

• Combine cooked kidney beans with black beans and white beans to make a colorful three bean salad.
• Mix with tomatos and scallions and dress with olive oil, lemon juice, salt and black pepper.
• Serve cooked kidney beans over a piece of cornbread and top with grated cheese for a twist on the traditional tamale pie.
• In a food processor or blender, combine cooked kidney beans with garlic, cumin and chili peppers for a delicious spread that can be used as a crudité dip or sandwich filling.
• Make a pot of chili, the hearty Mexican soup that traditionally features kidney beans.
• Make tacos with a vegetarian twist by using kidney beans in place of ground meat.

Individual concerns

Oxalate content

Kidney beans have consistently been determined to have high oxalate content. Oxalates are naturally occurring organic acids found in a wide variety of foods, and in the case of certain medical conditions, they must be greatly restricted in a meal plan to prevent over-accumulation inside the body. Our comprehensive article about oxalates will provide you with practical and detailed information about these organic acids, food, and health.

Kidney beans and phytohemagglutinin

In raw form, kidney beans can contain excessively high amounts of a potentially toxic substance called phytohemagglutinin. This substance is classified as a lectin glycoprotein, and in sufficiently high amounts it has been shown to disrupt cellular metabolism. The amount of this toxin in beans is usually measured in terms of hemagglutinating units, or hau. In their raw form, red kidney beans can contain 20,000 to 70,000 hau. This number drops down to 200 to 400 hau with fully cooked red beans. White kidney beans start off with about 1/3rd less hemagglutinin than red ones.

Nutritional profile

One cup (177g) at 225 calories provides molybdenum (295% DV), folate (58% DV), tryptophan (56.2% DV), copper (42% DV), fiber (40% DV), phosphorus (35% DV), manganese (33% DV), protein (31% DV), vitamin B1 (23% DV), iron (22% DV), potassium (20% DV), magnesium (19% DV), vitamin K (18.6% DV).