Looking for that fruit or vegetable that might prevent cancer?

Blueberries. Green tea. Tomatoes. And, oh, that cruciferous cauliflower. All make the lists of super foods that might help prevent cancer. Then there are the foods such as smoked meat and fried foods that supposedly might cause cancer. Such information is standard fare for TV doctors and Web sites, but most of us don’t know how to judge such claims.

What sounds authoritative may not be. Only about half of the recommendations on two internationally syndicated TV medical talk shows were supported by scientific evidence, according to a recent study in the journal BMJ.

“The messages that the public is getting are bits and pieces, without the big picture,” said Walter Willett, chair of the Department of Nutrition at the Harvard School of Public Health. “It’s sort of the Wild West out there in terms of what people hear about nutrition and cancer.”

Of course, the blueberries we eat today are good for us. But nutrition’s role in cancer prevention is much more complex than a single dietary component: Evidence has mounted, for example, that lifestyle — diet, weight control and exercise — is vital in helping reduce risk. For now, experts endorse general dietary advice that is healthful for a variety of chronic diseases and conditions, rather than reductionist thinking that focuses on single foods or nutrients.

Reductionist thinking neglects the broader approaches of cancer nutrition research, including eating patterns and the mechanisms of microbiology. The quest now is for answers about nutrition’s relationship to the many challenges of cancers, challenges that go beyond any individual study.

Cancer is complicated
When you hear that a certain food helps prevent cancer, ask: Which cancer? “Cancer is multiple diseases,” said Marian Neuhouser, a nutritional epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle.

Whereas cardiovascular disease might be broken down into several types, including myocardial infarction, stroke and peripheral vascular disease, she said, “for cancer, it’s really over 100 different diseases.”

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