Carcinogens in meat
The bulk of evidence — from the NIH-AARP study and many others — links red meat to an increased cancer risk, especially colon cancer. And pork is not "the other white meat." It counts as red meat, along with lamb.
Sinha says that components of the meat itself seem to be related to cancer. The trigger may be the carcinogens formed when meat is pan-fried or cooked over an open flame — especially when it's charred.
The cancer risk also could be tied to the naturally high iron content of red meat. Moreover, high concentration of nitrites — added to processed meats as a preservative — may also explain why hot dogs, luncheon meats and bacon are linked to cancer.
To lower your risk, the AICR's Bender recommends no more than 18 ounces of cooked red meat a week — for example, a hamburger, a small steak and two pork chops. She suggests garbanzo and kidney beans, as well as dried peas such as lentils, for healthy, inexpensive sources of protein.
For cancer prevention, Bender recommends that you fill two-thirds of your plate with "plant-based" foods — vegetables, beans, whole grains and nuts — and no more than a third with animal-based foods such as chicken, seafood, lean beef or low-fat dairy products.
Briefly precooking meat (including beef, pork, fish or chicken) either in the microwave or by parboiling before grilling reduces cancer-causing compounds — it limits the time meat is exposed to high heat on the grill, says Bender. Don't worry about grilling vegetables — carcinogens are not formed when veggies are exposed to high heat.
Fruits, veggies, grains and cancer
Although cancer prevention groups recommend a diet rich in fruits and vegetables, some researchers contend we've oversold their protective qualities.
"This isn't to say that there's absolutely no benefit to fruits and vegetables for cancer risk, but if there is some benefit, it's pretty small and probably limited to specific cancers," says Willett, the Harvard nutrition expert. Bender says the large study Willett refers to examined whether all fruits and vegetables prevented all cancers and found only a small benefit. However, she says, each cancer has different causes and pathways. "Lumping everything together dilutes the message we have about vegetables and fruits."
Willett agrees that there's good evidence for the benefits of a few nutrients in fruits and veggies, such as lycopene — found in tomatoes, pink grapefruit, cabbage and beets. It seems to help protect against prostate cancer, he says. Cooked tomatoes, such as in tomato sauce, and small amounts of fat improve lycopene absorption and enhance the benefit.