No one food is a magic tonic for better health, but some pack a bigger nutritional wallop than others. These seven superfoods may not turn you into an action hero overnight, but they will deliver the vital antioxidants, vitamins, and minerals you need to stay buff, day in and day out.

Tea  A cup a day can keep the cardiologist away, according to a recent study from Brigham and Women's Hospital in Boston. The study found that people who drink one or more cups of black tea each day were 44 percent less likely to suffer a heart attack than those who didn't sip. Tea is chock full of flavonoids—substances that keep the blood from clotting—which may reduce heart attack risk. (Note: Some research indicates it may take up to six cups a day to achieve the heart-healthy effect.) Animal research shows that green tea is also loaded with antioxidants (called polyphenols) that may prevent arthritis and certain cancers.

Sweet potato  "One of the most nutritious vegetables you can eat," raves the Center for Science in the Public Interest. Six ounces of sweet potato provides the RDA (15 mg) for beta-carotene, a carotenoid (plant pigment) with cancer-fighting antioxidant properties. Sweet potatoes are also rich in vitamin C and potassium.

Oats  What oats lack in romance they more than make up for in nutritional value. Researchers at Brigham and Women's Hospital found that women who ate two to three servings of whole grains per day (that includes whole grain bread, popcorn, brown rice, and oatmeal) reduced their risk of heart disease—the leading cause of death among women—by 27 percent. Oats have also been found to improve gastrointestinal function and glucose metabolism while decreasing blood cholesterol.

Tomato  Several studies indicate that tomatoes, and specifically a carotenoid called lycopene, may help prevent cancers of the breast, pancreas, prostate, and colon as well as cardiovascular diseases: Mediterranean populations with diets rich in tomatoes have a low incidence of these chronic diseases. Raw tomatoes aren't as beneficial as cooked ones, though, so break out the sauce pot: The cooking process releases the lycopene so it's more readily absorbed by the body.

Broccoli  Once snubbed by former president George Bush, broccoli is the superstar of the vegetable aisle. It is full of the B vitamin folacin (one cup delivers 80 mg), which may protect against some birth defects and heart disease, and contains a healthy dose of calcium. As with tomatoes, cook your broccoli for maximum benefits.

Soy  For centuries, Eastern cultures have reaped the benefits of a diet rich in soy protein: Studies indicate that soy's isoflavones—natural compounds that act like estrogen in the body—can lower blood cholesterol, may prevent hormone-related cancers of the breast and prostate, and can alleviate menopause symptoms such as hot flashes. Soy is also a good source of calcium, soluble and insoluble fiber, and protein—an eight-ounce serving of tofu contains about the same amount of protein (16g) as a 3.25 ounce steak. Experts recommend eating 17 to 25g of soy protein a day. (An 8-ounce serving of soy milk contains 7g.)

Blueberries  Not since Fats Domino's classic song topped the charts has this vibrant fruit garnered so much attention. In a recent Tufts University study, elderly rats (about 70 in human years) were fed a diet rich in blueberries (approximately one cup a day), which radically improved their declining balance and coordination skills. "I've never seen anything like it," says the study's leader, Jim Joseph, Ph.D., chief of the neuroscience lab at the USDA Human Nutrition Research Center on Aging at Tufts. The fruit's polyphenolic compounds (the antioxidants that give blueberries their color) are natural anti-inflammatories, says Joseph. Cooking the berries or freezing them right after picking increases their antioxidant properties.