Legumes help prevent a wide range of diseases. What's their magic?
In everything from Latin America's gallo pinto to Japan's sweet azuki desserts, beans have enjoyed worldwide culinary status for thousands of years. Today, in some nations, per capita bean consumption approaches a hundred pounds annually. Beans are gaining popularity in the United States, too, and for good reason: They're high in protein; low in fat; loaded with vitamins, minerals, and fiber—and they're quick and easy to prepare.
Beans belong to the legume family (Leguminosae), which includes lentils and peanuts. All varieties of beans boast roughly the same stellar nutrients. Their chief virtue is folic acid, a B vitamin that reduces the risk of neural tube defects in developing fetuses and helps regulate levels of homocysteine, a risk factor for heart disease. Beans are also a good source of iron and zinc—especially important for legume-loving vegetarians who forgo zinc- and iron-rich meat.
Beans are well-known as an excellent source of low-fat protein; one cup of beans has up to 16 grams of protein, as much as a 3-ounce serving of chicken or fish and twice as much as an ounce of cheddar cheese or a boiled egg. And although beans lack certain amino acids, rendering them an incomplete protein, simply adding a serving of grains fills the gap. "You don't even have to eat beans and grains at the same meal," says George Hosfield, PhD, research geneticist with the USDA's Agricultural Research Service. "As long as you eat grains on the same day you eat beans, you're covered.
In addition to protein, beans contain more healthy soluble fiber than grains and most other vegetables, which makes them good for lowering cholesterol and blood sugar and possibly helping reduce cancer risk. A cup of kidney beans, for example, contains two to three times as much soluble fiber as a cup of brown rice, for the same number of calories. Soluble fiber is significant because it absorbs bile acids and salts, says certified nutrition specialist Shari Lieberman, PhD, author of The Real Vitamin and Mineral Book (Avery, 2003). "The body then uses its cholesterol stores to make more bile acids and salts, so the overall effect is a lowering of cholesterol," she says. In fact, eating beans can reduce total cholesterol by 7 percent, lowering harmful LDL cholesterol levels and increasing protective HDL levels (British Journal of Nutrition, 2002, vol. 88, no. 3 Suppl). Studies indicate that beans' soluble fiber may also help reduce the risk of cancer, especially of the colon (Epidemiology, 1997, vol. 8, no. 6).
Beans are also helpful in preventing obesity and diabetes. Because they're low on the glycemic index (a ranking of carbohydrate-rich foods based on their potential ability to raise blood sugar levels), legumes are an important dietary option for people who are diabetic or overweight. In addition, beans create a sense of fullness and help control food cravings (British Journal of Nutrition, 2002, vol. 88, no. 3 Suppl).
The secret is in the soaking:
- In a large pot, cover beans with filtered water. Soak overnight.
- Drain beans, rinse thoroughly, and add 4 cups fresh water for each cup dry beans. Place in a large pot with a tight lid.
- Add a 3- to 4-inch strip of kombu (a sea vegetable), to make beans easier to digest.
- Bring to a boil. Reduce heat and simmer for 1-4 hours, depending on variety. Cook beans until they're soft.
Short-soak method: Cover beans with water and boil 5 minutes. Remove from heat. Cover and set aside for 2-3 hours. Drain and rinse, then cover with fresh water and cook as above.
What About Gas?
The downside of beans is that they can be difficult to digest because of carbohydrates called oligosaccharides that pass undigested into the lower intestine. Hard beans, such as great Northern, kidney, red, and garbanzos, are toughest to digest; softer legumes, such as mung, azuki, split peas, black-eyed peas, and lentils, are easiest. Soybeans tend to cause the most gas trouble. "Most [soybean] strains are very hard and contain an enzyme that interferes with protein digestion by blocking an enzyme in the stomach," says Tom Chasuk, author of The Bean Gourmet Presents the Greatest Little Bean Cookbook (iUniverse, 2000). Fortunately, certain cooking and soaking methods make legumes easier on your digestion (see "Gas-Free Beans," right). Or try digestive enzymes, such as Beano, which are formulated to alleviate bean gas.
Canned Beans OK
You may think canned beans are less nutritious than fresh beans, but that's not the case. "Most beans are canned in the water they're cooked in, so any minerals that may have been lost during cooking are reabsorbed," says Lieberman. Add the canning water to your bean recipe for a little extra nutrition, but be aware that the liquid may contain some of the indigestible sugars—thus leading to more gas. If you want to play it safe, drain the canning liquid and rinse beans thoroughly.
A Natural Fit
The best part about beans is they go with almost any meal. Purée great Northern or cannellini beans with a little chicken stock or skim milk to make a creamy, fat-free base for soups. Blend garbanzos with olive oil, garlic, and lemon juice and use instead of mayo as a sandwich spread. Add any cooked legumes to salads, soups, or grain dishes. And try these nutrition-packed recipes. Not only do they taste good, they're good for your health.
Lisa Turner is a researcher and writer in the field of natural health and nutrition.