How Food Fight Cancer

The growth of a malignant tumor is a long, slow process that involves three key steps: the initiation of potentially cancerous changes in a cell’s DNA, the promotion of uncontrolled growth in a damaged cell and the progression of a cancerous lesion into a mass that can invade other tissues. Preliminary evidence suggests that nutrients found in particular foods can interfere with each of these steps.

What does food have to do with all this? Quite a bit, by most estimates. “Humans put two to three pounds of food into their bodies every day,” says Koo. “It’s our greatest contact with the environment.” Population studies have consistently linked a high intake of plant foods to a low risk of cancer. And as molecular biologists have discovered during the past decade, the compounds contained in those foods can work in very specific ways to block the development of tumors. No one is holding up green tea and garlic as adequate treatments for advanced disease. The goal of the new prevention diets is to reduce the need for such treatments. As Gaynor puts it, eating the right foods is “as specific to stopping cancer before it starts as wearing a seat belt is to lowering your risk of a fatal automobile accident.”

Fruits and vegetables are loaded with antioxidants. Vitamin C, E and beta carotene can help neutralize the free radicals that degrade cellular DNA. They even help protect each other, C preventing oxidative damage to E, and E blocking the oxidation of beta carotene. But vitamins are just beginning of the antioxidant story; researchers have recently identified several plant chemicals that may have far stronger effects. Grapes and red wine are rich in an antioxidant called resveratrol, which reduced the incidence of skin tumors in mice by 88 percent in one recent study. Green tea contains several potent antioxidant chemicals known as polyphenols. Researches estimate that one of them, a compound called EGCG, has 20 times the radical-quenching effect of vitamin E, and 500 times the effect of vitamin C.

Then there’s lycopene, the pigment that gives tomatoes their blush. You can’t get much lycopene from a raw tomato; it’s too tightly bound by the fruit’s proteins and fibers. But cooking frees it for absorption by the body, and dietary fat helps carry it into the bloodstream. If that’s not reason enough to enjoy some tomato sauce with a dash of olive oil, consider this. In a 1995 study 48,000 men, Harvard researchers found that those who ate 10 servings of tomato rich foods every week cut their risk prostate cancer by nearly half. Other studies suggest that lycopene may help ward off cancers of the breast, lung and digestive tract.

If you make tomato sauce, do not forget to add some garlic. Just as lycopene helps ward off oxidative damage, the allyl sulfides found in garlic chives and onions may help the body process cancer-causing more safely. You’ll recall that the liver’s phase I enzymes break down potential carcinogens as they enter the body, leaving them in a more reactive state until they’re carted away by phase II enzymes. Allyl sulfides can modulate phase I activity, presumably reducing the volume of debris that our cells have to contend with. “Even modest amounts of garlic in the diet have a marked impact on metabolisms,” says nutritionist John Milner of Pennsylvania State University. You don’t have to cook the clove to get the effect, but the allyl sulfides won’t fully form unless you cut it up and let it sit for 10 minutes. Milner suggests buying aged garlic extract, which has known the most potency in lab studies.

Garlic isn’t the only food that could help you handle carcinogens more deftly. Just as garlic can dampen phase I activity, cruciferous vegetables such as broccoli, cauliflower and cabbage may boost production of the phase II enzymes that cart away chemical debris. The credit goes to sulforaphane, a sharp-tasting chemical that insects (and some humans) find repellent. Johns Hopkins pharmacologist Paul Talalay discovered six years ago that sulforaphane could activate a gene that boosts production of important phase II enzymes. To test its protective effects he injected rats with a potent carcinogen called DMBA, and gave some of them sulforaphane as well. Tumors cropped up in 68 percent of the untreated animals, yet only 26 percent of those high doses of sulforaphane got sick. Does that prove that broccoli prevents cancer in people? Of course not, but it provides a good excuse to munch some.