You exercise. You don't smoke. In fact, you make a big point of gagging and choking loudly whenever anyone else lights up. What else can you do to lower your chances of developing cancer?

Eat up! But eat wisely, says Colleen Doyle, M.S., R.D., director of nutrition and physical activity for the American Cancer Society. "There's no magic bullet, but following an eating plan with a variety of low-fat foods—including fruits and vegetables, whole grains, and beans—can make a big difference."

Battle Cancer with Color.

Eat at least five servings of fruits and vegetables each day. And go for the ones with color. Antioxidants and phytochemicals—known cancer-fighting agents—actually provide the rich hues of colorful fruits and vegetables such as broccoli, tomatoes, carrots, oranges, and strawberries. "We don't know which antioxidants and phytochemicals are most protective, so we tell people eat a wide variety," says Doyle. One serving of fruit is the equivalent of half a grapefruit, a quarter of a cantaloupe, or 1 medium-size apple, banana, or pear; a serving of raw vegetables is about 1/2 cup—approximately the size of your fist.

Go for the Grains.

Aim to eat six to 11 servings of grain foods (i.e., 1/2 cup cooked cereal, 1 slice bread, 1/2 cup brown rice) each day, making sure that at least half those servings are whole grains. Grains also provide hefty helpings of fiber, which is believed to help fight colon cancer. They also contain cancer-combating minerals such as calcium, folate, and selenium, and are low in fat—another factor in fighting cancer. "But make sure to select products that list 'whole grain' as the first ingredient. 'Wheat flour' is not the same as 'whole wheat flour,' "Doyle warns.

Bring on the Beans!

Beans not only are loaded with fiber but also contain cancer-combating phytochemicals called isoflavones. "We suggest including beans in things you don't normally think of," says Doyle. "Throw some black beans into your Mexican rice, chickpeas on your salad, or kidney beans in your chili." And don't forget soybeans, which have the highest concentration of these isoflavones.

The bonus to following this anticancer eating plan? You'll feel healthier—right now.