A little less fat won't cut cancer risk.

A little less fat won't cut cancer risk

Small sacrifices to reduce dietary fat -- such as leaving the butter off your bread -- may be good for your heart but probably won't reduce your risk of colon, breast or prostate cancer, according to the results of a 17-year study of the link between diet and cancer.

Researchers with the Centers for Disease Control (CDC) in Atlanta found no difference in the risk of these three cancers among 13,330 men and women whose diets were analyzed twice between 1971 and 1987 as part of the National Health and Nutrition Examination Study. Colon, breast and prostate cancer proved just as likely to develop in the people with the lowest fat intake as in those who ate higher levels of fat.

"Although it is a good idea to reduce fat intake, ... modest reductions will not appreciably alter the cancer rate for breast, prostate and colon," said study director Tim E. Byers last week at the annual meeting of the Federation of American Societies for Experimental Biology, held in Atlanta.

He points out, however, that individuals with the lowest dietary fat levels in his study still ate more fat than the American Heart Association or National Research Council recommends. All participants consumed between 32 and 38 percent of their total calories in the form of fat; the recommended maximum is 30 percent. The average U.S. diet derives 38 percent of its calories from fat.

Byers says the new findings support animal studies and cancer-rate comparisons among countries with varying levels of fat consumption, which have suggested that people need to slash their fat intake to between 20 and 25 percent of total caloric intake in order to lower their cancer risk. A study of women in northwest Italy, for instance, showed that those who derived less than 30 percent of their calories from fat had half the normal rate of breast cancer for that region (SN: 2/18/89, p.102).

John H. Weisburger, a cancer prevention researcher at the American Health Foundation in Valhall, N.Y., adds that Byers' report dovetails with his own findings in animals. "It has been our experience that if the lowest fat intake was not lower than 30 percent, you wouldn't see a decrease [in cancer rates]," he told SCIENCE NEWS.

A diet of 20 percent fat, says Byers, would feature large portions of fruits and vegetables, virtually no cooking fat, and only small servings of extremely lean meat. But he urges people not to abandon attempts to trim their fat intake if they find they can't stick to such spartan fare. In the battle against heart disease and obesity, he stresses, modest fat reductions still pay off.