CHICAGO, IL -- March 9, 1999 -- Researchers have found no evidence that lower fat intake is associated with decreased risk of breast cancer, according to an article in tomorrow’s issue of The Journal of the American Medical Association.

Michelle Holmes, M.D., Dr.P.H., of Harvard Medical School and Brigham and Women's Hospital in Boston, and colleagues studied 88,795 women in the Nurses' Health Study who were free of cancer in 1980 and followed up for 14 years. The authors investigated the relative risk of invasive breast cancer for an incremental increase of fat intake, ascertained by food frequency questionnaires in 1980, 1984, 1986 and 1990.

"We found no evidence that lower intake of total fat or particular types of fat over 14 years of follow-up was associated with a decreased risk of breast cancer," the authors write. "These findings suggest that reductions in total fat intake during midlife are unlikely to prevent breast cancer and should receive less emphasis. Rather, women's decision about fat intake should be guided primarily by risk of heart disease, which is strongly influenced by the type but not total amount of fat."

The researchers found no evidence that lower intake of total fat or specific major types of fat (animal fat, vegetable fat, polyunsaturated fat, saturated fat, monounsaturated fat, trans-unsaturated fat, cholesterol and omega-3 fat from fish) was associated with a decreased risk of breast cancer.

"In this large prospective study, we found no evidence that higher total fat intake was associated with an increased risk of breast cancer, even though the relationship was assessed many different ways," the researchers write. "Contrary to the prevailing hypothesis, the overall trend was inverse and statistically significant."

According to the researchers, high intake of total dietary fat has been postulated to increase risk of breast cancer. Some researchers have suggested that fat intake should be 20 percent or less of caloric consumption for a protective effect to be evident and have maintained that such a protective effect has not been found in cohort studies because they were conducted in Western populations in which the level of fat intake is rarely this low.

The authors found no increase in the risk of breast cancer with increased intake of animal fat, polyunsaturated fat, saturated fat or trans-unsaturated fat in the women who replaced carbohydrates with fat. They found no evidence of decreased breast cancer risk with increased intake of vegetable fat or monounsaturated fat. Contrary to the predominant hypothesis, an increased risk of breast cancer was associated with omega-3 fat from fish.

Thanks to The Doctor's Guide to the Internet™ for the article