Study: Animal Fats Linked with Breast Cancer

Young women who eat more red meat and full-fat dairy products such as cheese may be raising their risk of breast cancer, researchers reported. They said their study, published in the Journal of the National Cancer Institute, provides yet another incentive for women to shun fatty foods and consume fresh fruits, vegetables and whole grains.

“When we compared the women in the highest fat intake group with women in lowest intake group, those with the highest intake had a 33 percent greater risk of invasive breast cancer,” Eunyoung Cho of Brigham and Women's Hospital and Harvard Medical School said in a telephone interview. Cho said her study was unique because it included women who had not reached menopause. Breast cancer takes years to develop, although it usually shows up after menopause, and factors early in a woman's life may be important.

Women most at risk of breast cancer obtained, on average, 23 percent of calories from animal fat, versus 12 percent in the lowest-risk group. Vegetable fats such as olive oil did not affect a woman's risk. “We found that it was not total fat but certain types of fat that was related to breast cancer risk,” Cho said.

The study of more than 90,000 women aged 26 to 46 was taken from the Nurses' Health Study, in which volunteers answer regular questionnaires about diet and lifestyle and that data is analyzed by researchers who track the women's health. Over the eight years of the study, 714 women developed invasive breast cancer. “Overall, we observed that there was a higher risk of breast cancer among women who ate foods rich in animal fat such as red meat, cheese, ice cream and butter during their 20s, 30s and 40s,” Cho said.

Controversial area

“In an area of breast cancer research that has yielded often starkly different findings, we have illustrated that there may be stronger support for lowering overall animal fat intake, especially during a woman's early adult life,” she added. Hydrogenated oils, hardened to be more like butter and lard, clog arteries just like butter and lard do. Last week the U.S. government said it would require food manufacturers to label foods with trans-fats -- found in animal and hydrogenated fat. Researchers have long noted that the rates of certain cancers are higher in the West than in Asia. But it has not been clear whether that is due to what people eat -- such as animal fat and dairy products -- or what they do not eat -- perhaps soy, vegetables or other products.

Cho, an epidemiologist who studies patterns of disease as well as a nutritionist, said it is not clear how animal fat may cause cancer. “Fat intake in general has been hypothesized to increase circulating hormone levels such as estrogen levels,” she said. Cooked red meat contains cancer- causing agents and is also linked with colon cancer. Eating less meat and full-fat dairy can also help a woman reduce her risk of heart disease, the No. 1 killer of both men and women in the industrialized world, Cho said.

According to the World Health Organization, more than 1.2 million people will be diagnosed with breast cancer this year. Breast cancer will kill more than 40,000 Americans this year.

(Reuters, 15 July 2003)