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Heroes or zeroes?

Not long ago, people believed they couldn’t do much to prevent cancer. “Bad” genes and other uncontrollable risk factors seemed to make the disease a matter of fate. Today, doctors know you can cut your risk for cancer if you refrain from smoking, maintain a healthy weight and stay physically active. What’s more, scientists are investigating whether certain chemicals in foods and supplements have an edge over others when it comes to protecting you against cancer.

The following five items are frequent headline-grabbers. Do they offer hope or are they just hype? Here’s what the latest research has to say.

Soy

How it can help: Soy foods, like tofu, tempeh, soy milk and soy nuts, contain phytochemicals that can potentially lower the risk of estrogen-dependent cancers. According to the National Cancer Institute (NCI), studies show that populations that eat large amounts of soy-based products have fewer incidences of breast, colon, endometrial and prostate cancers.

How it may hurt: Studies on humans to explore soy’s cancer-fighting ability are inconclusive, the American Cancer Society (ACS) reports. Some scientists are concerned that eating too much soy can increase cancer risk. As a result, the ACS advises breast cancer survivors to consume only moderate amounts of soy foods.

Tomatoes

How they can help: The American Institute for Cancer Research says that diets high in tomatoes are associated with a lower risk of cancers of the prostate, stomach and pancreas. Their beneficial ingredient, lycopene, is more readily absorbed by the body when tomatoes are cooked or processed (so opt for tomato sauce, pizza sauce and tomato juice) or served with a small amount of fat, such as olive oil.

How they may hurt: They don’t, unless your stomach is sensitive to tomatoes’ acidity. If so, you can get lycopene from watermelon, papaya, pink grapefruit or pink guava.

Garlic

How it can help: Garlic, as well as onions, leeks, scallions, shallots and chives, contains compounds that slow or prevent tumor growth. The NCI says a strong link exists between garlic and a reduced risk of prostate and stomach cancer. To preserve garlic’s cancer-fighting benefit, wait 15 minutes after peeling before cooking it.

How it may hurt: Eating too much garlic can cause side effects such as stomach disorders, diarrhea, contact dermatitis, bronchial asthma and a decrease in serum protein and calcium levels.

Black and green tea

How it can help: Black and green tea contains antioxidants called catechins that, in the lab, prevent free radical damage to DNA, reduce abnormal cell growth and inflammation and help the body get rid of cancer-causing agents, the NCI reports. Animal studies and two Chinese studies on humans show promising results, but the ACS says not enough data exist to prove that tea can fight cancer.

How it may hurt: Not all green and black tea contain caffeine, which can make you jittery and keep you awake at night.

Aspirin

How it can help: Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, lower stomach cancer risk at least 25 percent and reduce colon cancer risk, the ACS says.

How it may hurt: Since these drugs can cause potentially fatal bleeding in the stomach and brain, doctors seldom recommend them specifically for cancer prevention. Take a safer route—prevent stomach cancer with fresh fruits and vegetables and limit pickled foods and salted and smoked meats and fish.

The bottom line

To prevent cancer, the ACS recommends you eat three to five servings of vegetables and four or five servings of fruits a day, limit alcohol and red meats (especially fatty and processed meats) and choose whole grains over refined ones. Eating healthy foods in sensible amounts fights extra pounds that can promote cancer. A good diet also gives you energy and incentive to engage in exercise, another proven cancer-fighter.

Soy

Tomatoes

Garlic

Black and green tea

Aspirin

The bottom line