Natural Defense
Everything you need to know about cancer-fighting foods, supplements, and herbs

By Victoria Dolby Toews, MPH
Photo Illustration by Anne Elliot Cutting

A stunning 1.2 million Americans will receive the scary diagnosis of cancer this year alone, according to American Cancer Society (ACS) estimates. No wonder it often feels like everyone around you knows someone who has recently been diagnosed with the disease. Although it may seem like the genetic die has already been cast for those with a family history of cancer, experts estimate that only 5 percent to 10 percent of cancers are inherited. If you want to improve your odds of staying cancer-free, your first line of defense is to modify your lifestyle (the obvious first steps: stop smoking and start exercising) and your diet. In fact, what we eat may be the most controllable anticancer tool available to us. The ACS estimates that poor diet is the cause of up to 35 percent of all cancers, although some types, such as colon and prostate cancer, seem to have more of a tie to nutrition than others, such as breast and ovarian cancer. Luckily, a flurry of recent cancer research has uncovered foods, supplements, and herbs that may help in the fight against cancer. Here are some simple dietary steps you can take to stay healthy.

How The Damage Is Done
Cancer is actually a group of diseases that have one thing in common: the uncontrolled growth and spread of abnormal cells. When these cancer cells begin to invade surrounding tissues, healthy cells are damaged and even destroyed. If the spread of the disease can't be brought under control, it can be fatal.

Cancer gets its start in two stages: the initiation stage, in which a substance called an initiator alters the genetic code of a normal cell, and the promotion stage, in which a substance called a promoter encourages the now abnormal cell to begin multiplying. The initiation stage happens quickly and frequently. The promotion stage is more lengthy, allowing the slow growth of cancer to go undetected, sometimes for years or even decades. The third stage, the progression stage, is when cancer cells multiply rapidly, disrupt body functions, and eventually lead to death.

Bolster your diet to prevent cancer by adding whole foods that contain antioxidants.

Substances in food can act as initiators, which tend to be mutagens, or substances that cause genetic mutations. For example, the body converts food additives called nitrites, found in processed meats such as bacon and bologna, into carcinogenic nitrosamines. Other dietary mutagens include aflatoxin (a toxin produced by a mold that grows on peanuts); heavy metals; polychlorinated biphenyls (PCBs); and pesticides, such as malathion and DDT. Components of our diets can also act as promoters. Alcohol, for example, does not initiate cancer but it promotes the growth of existing abnormal cells.

Cancer-fighting Foods
The best way to bolster your diet to prevent cancer is to add whole foods that have natural anticancer properties. Antioxidants—including vitamins A, C, and E, carotenoids, and other nutrients and enzymes—are some of the most crucial components of a cancer-prevention diet. They preserve healthy cells by neutralizing free radicals—your body's worst enemy. Free radicals can react with and damage just about any molecule in the body, including fats, proteins, and even DNA. And when areas of damaged DNA accumulate, cancer can be the frightening consequence. Boosting consumption of antioxidant-rich fruits and vegetables—especially dark leafy greens, red peppers, tomatoes, berries, oranges, kiwi, and cantaloupe—is a way to lower the risk of most common cancers (Proceedings of the Nutrition Society, 2002, vol. 61, no. 2).

Research also suggests that including even small amounts of fish in your diet on a regular basis protects against cancer (American Journal of Clinical Nutrition, 1999, vol. 70, no. 1). Fish contains omega-3 essential fatty acids (specifically EPA and DHA), which help stop cancer growth. Superior sources of omega-3s include salmon, herring, sardines, cod, tuna, and mackerel. If you don't eat fish, flaxseed oil is also a source of omega-3s. Fish-oil supplements are another option, although some people experience mild stomach upset from these pills.

Numerous studies link a high intake of green tea to a lower risk of several cancers.

Those with a family history of breast or prostate cancer may want to pay special attention to a few foods that might aid in preventing these hormone-dependent forms of cancer. Antioxidant-rich soy, found in tofu, soy milk, soy yogurt, tempeh, and edamame, may in fact take cancer fighting to a new level. Several studies have linked substances in soy called isoflavones to a lower risk of hormone-dependent cancers (European Journal of Nutrition, 2001, vol. 40, no. 4). However, a recent study raises the possibility that soy might not be beneficial for people with existing prostate cancer (Annals of the New York Academy of Sciences, 2002, vol. 963). So although soy foods may make good sense as a preventive measure, speak with a doctor if you have an existing case of breast, prostate, or other hormone-dependent cancer before including large amounts of soy in your diet.

Members of the genus Allium—which include garlic, onions, leeks, and chives—may be your best buddies when it comes to protecting your stomach and the rest of your digestive system against cancer. In a study done in China, all the immune-enhancing allium vegetables showed a protective effect against both stomach and esophageal cancers (Japanese Journal of Cancer Research, 1999, vol. 90, no. 6). Another study of 41,000 women in Iowa found that eating garlic at least once a week reduced the risk of colon cancer by 35 percent (American Journal of Epidemiology, 1994, vol. 139, no. 1). Garlic may help prevent stomach cancer because of its antibacterial action against a possible cancer-promoting bacterium, Helicobacter pylori. Those with a sensitive nose or who don't like the taste of garlic can look for odor-controlled garlic supplements. People taking drugs to prevent blood clotting, however, should talk to their doctors before taking garlic supplements.

A spot of tea may also be good for the tummy. Numerous studies link a high intake of green tea to a lower risk of several cancers. In one study, researchers reported that tea protected against tumors of the gastrointestinal tract, the liver, and the lung (Wiener Medizinische Wochenschrift, 2002, vol. 152, no. 5­6). In another study, researchers examined the tea-drinking habits of more than 35,000 women during an eight-year period, finding that women who regularly drank two or more cups per day of non-herbal tea showed a lower risk of cancers of the digestive tract than women who never or occasionally drank tea (American Journal of Epidemiology, 1996, vol. 144, no. 2). Health care professionals recommend enjoying at least four cups of tea a day to benefit from the brew's cancer-protecting antioxidants.

Support From Supplements
Although whole organic foods should be your first line of defense against cancer in general, certain supplements have been shown to help prevent particular types of cancer. For example, folic acid, a B vitamin found in many vegetables, beans, fruits, whole grains, and fortified breakfast cereals, may hold promise as an anticolon-cancer wonder. Deficient intake of folic acid, which plays an important role in DNA synthesis and repair, has been linked to an increased risk of cancers of the colon and other organs (American Journal of Clinical Nutrition, 1997, vol. 65, no. 1). Animal studies have shown that diets lacking folic acid cause DNA strands to break in areas of the body most susceptible to cancer, leading to the spread of the disease (Gastroenterology, 2000, vol. 119, no. 1). Although the best sources of folic acid are foods—including dark green leafy vegetables, orange juice, and broccoli—you can look for folic acid in multivitamins, B-complex supplements, or stand-alone supplements.

Selenium has gained a solid foothold as an agent that can prevent colon, lung, and prostate cancer.

During the past few years, selenium has also gained a solid foothold as an agent that can prevent cancer, particularly of the colon, lung, and prostate (Proceedings of the Nutrition Society, 2002, vol. 61, no. 2). Selenium may reduce the risk of cancer through its role in the production of the antioxidant glutathione peroxidase—an enzyme that guards against free radical damage within cells. Several studies link selenium to cancer prevention, including a double-blind trial involving more than 1,300 individuals that reported a clear drop in cancer death rate in men taking 200 mcg of yeast-based selenium daily for four and a half years, compared with a placebo group (Cancer Epidemiology Biomarkers and Prevention, 2002, vol. 11, no. 7). Look for selenium in Brazil nuts, whole grains, and seafood. If you take a supplement, choose the natural yeast form rather than the selenite form, which isn't as easily absorbed by the body.

Get Herbal Protection
Herbs have long been used throughout the world for their medicinal and protective powers. Now medical studies suggest that several herbs may help prevent cancer. For example, a chemical in licorice root (Glycyrrhiza glabra) called glycyrrhizin blocks a component of testosterone and is therefore believed to be helpful in preventing the growth of prostate cancer (Journal of Agricultural and Food Chemistry, 2002, vol. 50, no. 4). Several other studies suggest that licorice extract—long known for its therapeutic benefits—may be potentially useful as an overall natural anticancer agent. Those using licorice should be cautious, however, because excessive amounts of licorice root can cause elevated blood pressure.

Another common kitchen herb, rosemary (Rosmarinus officinalis), also seems to boast anticancer properties. A recent study suggests that rosemary extract exhibits a protective effect against oxidative damage to DNA, which causes cancer (Cancer Letters, 2002, vol. 177, no. 2). This fragrant herb contains natural anti-inflammatory compounds, and because nonsteroidal anti-inflammatory drugs (NSAIDs) are associated with a reduced risk of several cancers, rosemary—as well as feverfew (Chrysanthemum parthenium) and turmeric (Curcuma longa)—may also help prevent cancer (Journal of Nutrition, 2001, vol. 131, no. 11).

Curcumin, the yellow pigment in the spice turmeric, appears to have strong anticancer properties. In fact, researchers believe turmeric may be responsible for the low rates of colorectal cancer in Asian countries because the spice has been so widely used for centuries in Asian diets. A member of the ginger family, the spice turmeric seems to inhibit the promotion and progression stages of cancer and boasts antitumor effects (Current Pharmaceutical Design, 2002, vol. 8, no. 19). So be sure to add some of this powerful spice to your recipes to benefit from its anticancer properties.

By combining these herbs and spices with antioxidant-rich foods and protective supplements, you'll be taking proactive steps to ensure you stay as healthy as possible in the years to come. And hopefully, as medical advances are made in the future, we'll gain even more valuable insight into the role diet plays in the fight against cancer.