They fight everything from cancer to heart disease -- even the signs of aging. But how do antioxidants work, and which foods contain the most? Here's what you need to know, along with power-packed summer recipes to help you maximize the benefits of these nutritional stars.

Recipes
Pecan Pancakes with Mixed Berry Compote
Tomato and Bean Salad with Grilled Tuna
Sweet Potato Hummus
Chicken Salad with Grapes, Avocado, and Almonds over Spinach

When even the label on a bottle of wine or chocolate bar boasts antioxidant capacity, you know the term has gone mainstream. Yet most of us would be hard-pressed to say what antioxidants are, despite knowing we need them. 

First, here's what they aren't: all alike. Roughly 10,000 chemicals in food act as antioxidants, from pigments to flavor compounds; essential nutrients like vitamins and minerals can act as antioxidants as well. What they have in common is the ability to disable free radicals, substances that harm the cells in your body and contribute to diseases like cancer. But they accomplish this in a staggering number of ways. Not only do many antioxidants fight specific kinds of free radicals, they also choose their own battlefields, says Jeffrey Blumberg, Ph.D., director of the Antioxidants Research Lab at Tufts University. "For instance, some antioxidants work in your brain," he says, "while others work in your liver." 

Specializing doesn't mean going it alone, however. Many antioxidants cooperate with each other; vitamin C, for example, boosts the free radical-quenching power of vitamin E. This kind of synergy has led scientists to use the collective term "antioxidant defense network"-and eating a diverse diet rich in antioxidant ingredients puts this vast resource to work. So how do you know what foods to choose? Generally speaking, the more colorful the item, the more anti-oxidant power it has. But that's not always the case. Use this primer to navigate your way.

Carotenoids
This group includes more than 500 mostly yellow-to-red pigments. Beta-carotene, which our bodies convert into vitamin A, may bolster our immune system, fight certain types of cancer, and help prevent heart disease. Carrots are an obvious source; you'll also find beta-carotene in sweet potatoes, winter squash, and apricots. Another carotenoid, lycopene (found in tomatoes, watermelon, and pink grapefruit), has been shown in studies to effectively protect the prostate from cancer. And lutein and zeaxanthin may guard your eyes from oxidative damage. Kale, corn, eggs, and spinach all include this duo.

Flavonoids
While the more than 4,000 flavonoids share a similar chemical structure, they're diverse in their health benefits as well as in the foods that harbor them. Anthocyanins win the prize for flashiest flavonoid." These bright red, purple, and blue pigments found in berries have been shown to improve eyesight, halt tumor growth, and protect against heart disease. Catechins, abundant in tea, chocolate, grapes, berries, and apples, may inhibit tumor growth. Quercetin, provided by onions, tarragon, and apples, has been shown to protect lungs and fight inflammation. Grapefruit contains naringin, which may lower cholesterol.

Isothiocyanates
These are responsible for the sulfur aroma and flavor of cruciferous vegetables such as broccoli, cauliflower, and cabbage. But what isothiocyanates lack in aromatic appeal, they make up for in effectiveness. They protect DNA in cells from damage by carcinogens. Sulforaphane, an isothiocyanate found in broccoli, may inhibit the growth of breast-cancer cells.

Vitamins and Minerals
Of the roughly three-dozen vitamins and minerals essential for good health, three act as antioxidants. Vitamin E scavenges free radicals that attack fat cells, particularly LDL cholesterol. Some evidence shows vitamin E may be effective against cataracts and cancer, particularly prostate cancer. Look for E in sunflower seeds, safflower oil, almonds, hazelnuts, and wheat germ.

After it disables a free radical, vitamin E's antioxidant capacity is rendered in-effective. That's where vitamin C comes in. C "recharges" E, giving it power to disable another free radical, a process that repeats itself up to 1,000 times. Vitamin C also protects proteins, fats, carbohydrates, and DNA from damage by free radicals. Eating vitamin C-rich foods has been associated with lower rates of lung and breast cancer. It's easy to find: Citrus, strawberries, peppers, kiwi, and tomatoes all have significant amounts.

Selenium is crucial for the formation of several antioxidant enzymes, some of which protect sperm and blood vessels from oxidative damage, while others help vitamins C and E perform. Find selenium in meat, seafood, grains, and nuts.