Many hungry for proof of cancer-fighting diets

Diet messages from groups such as The National Cancer Institute and the Prostate Cancer Foundation are everywhere. Yet scientists say they do not know whether dietary changes make a difference in cancer risk.

Most proposed dietary changes are unlikely to be harmful -- less meat and fat, more fish, fruits and vegetables. And they may protect against heart disease.

So should people who are worried about cancer follow these guidelines?

Dr. Barnett Kramer of the office of disease prevention at the National Institutes of Health said: "I think a lot of the public is completely unaware that the strength of the message is not matched by the strength of the evidence."

But Dr. Arthur Schatzkin of the National Cancer Institute said people want answers, even if they are not definitive.

Read more: Many hungry for proof of cancer-fighting diets