Cooking some vegetables even slightly can help boost bioavailability, Prior says. "Tomatoes are a classic example. Flavonoids in cooked tomatoes are better absorbed than raw tomatoes. We don't know for sure what's happening in the gut, but we do know this is true."
However, cooking is not always good. It kills antioxidants in some foods, he says. Until researchers figure it out, "aim to eat those at the higher end of the antioxidant chart," says Prior.
The Antioxidant Winner: Beans
Prior's study found beans to be clear winners - one-half cup of red beans yields 13,727 antioxidants; red kidney beans have 13,259; pinto beans, 11,864; and black beans, 4,191. Beans are inexpensive and filling. Classic meals such as beans and rice, beans in a burrito, split pea soup, and a peanut butter sandwich are bean naturals. (Peanuts are not nuts; they are in the same family of plants as beans and peas.)
One-third cup of cooked beans has 80 calories, no cholesterol, lots of complex carbohydrates, and little fat. In addition, beans are full of B vitamins, potassium, and fiber, which promote digestive health and relieve constipation. Eating beans may help prevent colon cancer and reduce blood cholesterol, a leading cause of heart disease, researchers say.
Beans are also a great protein source, says Cindy Moore, MS, RD, director of nutrition therapy at The Cleveland Clinic, and spokeswoman for the American Dietetic Association. "We used to say that you needed to eat grains with beans to make it a complete protein, but we no longer think that's true," she tells WebMD. "If you get some grains sometime during the day, you'll get the benefit of complete protein."
If beans bother your digestive system, try canned beans, she adds. Also, there's Beano, an enzyme supplement that breaks down gas-producing substances in the beans. Drinking more fluids also helps, as does regular exercise. Both help your intestinal system handle the increased dietary fiber.
"To sneak beans into your diet, one really easy thing is to put them in vegetable salads," Moore says. "If you're into convenience, mix some canned beans with canned soup or with a frozen entrée. You don't have to use all the beans in the can. Just scoop out what you want, rinse them, and keep the rest in the canned juice." Frozen beans work well, too.