Q. Is soy helpful or harmful for people at risk for, or with a history of, breast cancer?
A. Researchers believe that compounds in soy known as isoflavones act as weak plant forms of estrogen. By attaching to the same receptors as natural estrogen, these phytoestrogens are able to block natural human estrogen from entering breast cells and possibly triggering tumor formation. But research on the effects of soy isoflavone supplements?rather than soy foods?on breast cell growth and cancer risk has yielded conflicting results. Some studies have found that supplements might even encourage tumor formation, especially in women with a history of breast cancer.
Therefore, experts advise moderation even when it comes to soy food consumption. Women not at high risk can enjoy one to two servings a day of soy. But women who have, or are at high risk for, estrogen-dependent breast cancer should keep soy to a few servings a week. It’s best for everyone to avoid isoflavone supplements, which typically contain much larger doses than what’s in soy foods. For more protection, see ?EN‘s Best Bets to Reduce Breast Cancer Risk,? below.
Q. How do dairy and other calcium-rich foods affect cancer risk?
A. Calcium may actually protect against colon cancer; high intakes of calcium have been linked to lower rates of colon cancer, and calcium supplements were shown in some studies to modestly reduce the formation of colorectal polyps. However, some, but not all, studies have linked high dairy and calcium intakes to an increased risk of prostate cancer.
What to do? Don’t stop drinking milk. Enjoy a moderate amount of calcium-rich foods, like two to three daily servings of low-fat or nonfat milk and yogurt, to benefit from its bone-strengthening and blood-pressure-lowering effects. For more protection, see ?EN‘s Guide to Curtailing Colon Cancer Risk,? below.
Q. Does alcohol increase cancer risk?
A. Alcohol increases the risk of several cancers, including cancers of the mouth, liver and probably also the colon. The risk is multiplied by drinking and smoking together.
Alcohol may also increase breast cancer risk. Women who drink one alcoholic beverage a day have a small increase in risk; the risk is much greater for those who drink more. Women at high risk for breast cancer should avoid alcohol altogether. However, getting folate from foods like leafy greens, legumes and orange juice, and folic acid from fortified cereals and a daily multivitamin can help reduce alcohol’s risk.
Q.As a cancer survivor, can certain foods improve my long-term odds?
A. Although research is scant, researchers say it seems likely that what affects the development of primary cancer also affects its recurrence. Most experts believe that cancer survivors benefit from the same dietary guidelines recommended for cancer prevention. The exception is during treatment, when consuming enough calories may be more important than the kinds of foods you eat.
Q. Does soy protect against prostate cancer?
A. In animal and lab studies, soy isoflavones have shown promise in helping prevent and slow the progression of prostate cancer. Adding soy foods like soy burgers, soy nuts, soy milk and tofu to your daily menu is a good idea. For more protection, see ?EN‘s Tips for Prostate Protection,? above.
Q. Will eating grilled foods affect my chances of getting cancer?
A. Cooking meat, poultry or fish at high temperatures, especially over a direct flame, causes the formation of cancer-promoting compounds called heterocyclic amines (HCA’s). And when fat from food drips onto a heated surface like a grill, the resulting flare-up of fire and smoke causes additional cancer-causing compounds, polycyclic aromatic hydrocarbons (PAH’s), to form on these meats.
If you eat a lot of meats that are grilled or barbecued over an open flame?or that are pan-fried or broiled using high temperatures?you may increase your risk of stomach and colorectal cancers. To play it safe, cook by direct flame and at high temperatures only occasionally. When you do, marinate first; it can cut carcinogen formation by more than 90%. See more tips, above.
Q. Can vitamin and mineral supplements provide cancer protection?
A. While there is substantial evidence that diets rich in vegetables, fruits and other plant foods can reduce the risk of cancer, there is very little evidence that vitamin and mineral supplements can do so. Why is that? Plant foods contain many potentially healthful compounds, including numerous substances not yet identified. Experts believe these substances work best together, as they are found naturally in food.
In certain circumstances, supplements may even be detrimental. Research has shown that beta-carotene supplements actually increase lung cancer risk in smokers. Moreover, some experts suggest that in people undergoing cancer treatment, high doses of antioxidants may counteract the benefits of chemotherapy and radiation, ironically promoting tumor growth. Food has the advantage of rarely providing too much of any one nutrient. However, if you do fear coming up short, a daily multivitamin/mineral supplement may benefit you and poses no risk.– Adrienne Forman, M.S., R.D.