Only about 10% of all cancers are caused by genetics. The remaining 90% of malignancies are related to diet, weight and exercise...smoking...and/or environmental factors.
Even though most people realize that diet can affect cancer risk, few regularly consume a variety of the foods that contain large amounts of phytochemicals, substances that actually can inhibit the cellular damage that leads to cancer.
Eating a combination of cancer-fighting foods is the best approach because no single food supplies all the available protective substances—vitamins, minerals, phytochemicals and fiber.
Beans (legumes) have high levels of a cancer-fighting compound called phytic acid. They're also rich in fiber and saponins, chemical compounds that reduce the ability of cancer cells to proliferate.
The landmark Nurses Health study found that women who ate four or more servings of legumes weekly were 33% less likely to develop colon polyps than those who consumed one or fewer weekly servings. In people already diagnosed with colon polyps, those who ate more beans reduced their risk for a recurrence by 45%, compared with those who ate fewer beans.
Bonus: Beans are very high in protein. They're a good substitute for people who want to reduce their consumption of red meat-a major source of saturated fat, which can increase cancer risk.
Other cancer-fighting legumes: Small red beans, red kidney beans, pinto beans and garbanzo beans.
Helpful: If you don't want to spend time cooking dried beans, you can get many of the same benefits by eating canned. To reduce the sodium in canned beans, empty them into a colander and rinse thoroughly with cold water.
Recommended: Eat one-half cup of beans at least four times weekly.
Berries are rich sources of vitamin C and other antioxidants. People who regularly eat berries have a lower risk for malignancies of the colon, bladder, esophagus and prostate. Berries also may lower the risk for lymphoma and premenopausal breast cancer.
Blueberries are an excellent choice for cancer prevention because they are among the richest sources of antioxidants, chemical compounds that protect cells from free radicals that can damage cell DNA-the first step in cancer.
Development: Much of this nutritional power comes from their high levels of anthocyanidins, a type of antioxidant that reduces the ability of carcinogens to damage DNA.
Bonus: Because berries are both filling and low in calories, they can be substituted for other sweet snacks to promote weight loss-which further reduces the risk for many cancers.
Other cancer fighting berries: Blackberries, strawberries, raspberries and cranberries.
Helpful: Keep frozen berries in the freezer. They can be kept almost indefinitely without spoiling and provide virtually the same nutritional benefits as fresh berries.
Recommended: Aim for at least one half-cup serving of berries per week.
Broccoli is a cruciferous vegetable that is rich in isothiocyanates, a family of phytochemicals linked to a reduced risk for colon, prostate, lung and premenopausal breast cancer. One of these phytochemicals, sulforaphane, reduces the ability of carcinogens to cause cell damage—and may increase the tendency of cancer cells to self-destruct, a process called apoptosis.
A study published in the Journal of the National Cancer Institute reports that men who consumed three or more weekly servings of broccoli (raw or cooked) were 41% less likely to get prostate cancer than those who consumed less than one weekly serving.
Other cancer-fighting cruciferous vegetables: Cauliflower, brussels sprouts, cabbage and kale.
Helpful: If you don't like the strong taste (and smell) of cooked broccoli and other cruciferous vegetables, eat them raw or lightly sauté them in olive oil or canola oil for three to four minutes.
You also can microwave or steam them. (Long cooking, such as boiling for 15 minutes or more, causes the release of strong-smelling tasting sulfur compounds.)
Recommended: Aim for three to five half-cup servings per week of cruciferous vegetables.
Garlic is an allium, which is a family of plants that contain allyl sulfides, phytochemicals not found in any other foods.
The lowa Women's Health Study found that people with the highest intake of garlic (at least one serving weekly) had a 32% lower risk of developing colon cancer than those who never ate garlic. Garlic has also been linked to a lower risk for prostate, lung, breast and skin cancers.
Bonus: Garlic can be used as a flavor enhancer to make healthful foods-vegetables, beans, whole grains, etc.—more enjoyable... and it reduces the need for unhealthful flavorings, such as salt and butter.
Other cancer-fighting alliums: Onions (all types), leeks and chives.
Helpful: To reduce the strong taste, use cooked garlic (by sautéing or roasting it, for example) rather than raw. The flavors mellow with long cooking. Wait 10 to 15 minutes after chopping garlic before cooking, to allow the active form of the protective phytochemicals to form. The cancer-fighting properties of jarred garlic are unknown.
Recommended: Aim to eat one to three cloves of garlic per week.
Walnuts provide fiber and are rich in omega-3 fatty acids, the same healthful, anti-inflammatory fats that are found in fish. Reducing inflammation in the body helps prevent cell damage that can lead to cancer.
Other cancer-fighting nuts: Almonds and hazelnuts.
Helpful: Buy packaged or bulk shelled, unsalted nuts (raw or roasted). Substituting nuts for other snacks improves the body's ratio of omega-3 to omega-6 fatty acids-important for lowering inflammation and cancer risk.
Recommended: Eat three to five one-third-cup servings weekly
Whole-grain bread is high in fiber. As fiber and certain starches resistant to digestion are fermented in the colon, substances are produced that block the cancer-promoting effects of bile acids. In addition, whole grains are higher in antioxidant vitamins (including vitamin E) and phytochemicals, called phenols, than are refined grains.
When scientists analyzed and combined the results from 40 different studies, they found that people who ate the most whole-grain bread and or other whole grains had a 34% lower risk for cancer overall than those who consumed less.
Other cancer-fighting whole grains: Whole-wheat pasta, whole-grain breakfast cereal, brown rice, bulgur, kasha and quinoa.
Helpful: When shopping for whole-grain bread or cereal, don't be misled by terms like multigrain, which merely means that more than one type of grain is included.. and don't judge by brown color, which can result from added caramel coloring. Check the ingredients list to make sure a whole grain is listed first, such as whole wheat or whole rye. "Flour" or "wheat flour" means that the product contains refined flour made from wheat—not whole-grain flour.
Recommended: Aim for three daily servings -one-half cup of whole grains or a slice of wholegrain bread counts as one serving