monounsaturated fats -- the kind found in olive and canola oils -- may significantly reduce the risk of breast cancer. It also found that women whose daily diets included polyunsaturated fats -- those found in other varieties of vegetable oils and seafood -- had a strongly increased breast-cancer risk. The findings by researchers who studied more than 60,000 women in Sweden appear in today's issue of Archives of Internal Medicine , published by the American Medical Association. "Our results indicate that various types of fat may have specific opposite effects on the risk of breast cancer,'' wrote the authors, led by researcher Alicja Wolk at Karolinska Institute in Stockholm.

Epidemiologists at Harvard's School of Public Health also participated. The results generally are in line with previous studies, though research linking A fatty diet may decrease brast cancer risk that various types of fat may have specific opposite effects on the risk of breast cancer,'' wrote the authors, led by researcher Alicja Wolk at Karolinska Institute in Stockholm. Epidemiologists at Harvard's School of Public Health also participated. The results generally are in line with previous studies, though research linking polyunsaturated fats with breast cancer risk is less clear-cut, said Dr. Neal Barnard, head of the Physicians Committee for Responsible Medicine, a Washington-based educational and research group. "It's an important study but it has tremendous potential for being misinterpreted,'' Barnard said. For one thing, the study population was homogenous -- Swedes generally have a high-fat diet that would tend to skew the results, Barnard said. "It's like trying to find inferences in lung cancer rates when everybody is a smoker,'' he said. "People who got it would be differentiated by something else other than smoking.'' The study subjects' daily fat intake averaged 30 percent of total calories consumed. U.S. federal guidelines advise limiting fat to no more than 30 percent of total calories, but Barnard said that's still too high to be healthful and more than triple the fat intake of societies where breast cancer rates are extremely low, such as rural China. Barnard also cautioned that the findings "should not be interpreted as a license to glug the olive oil.'' Regardless of its source, "every gram of fat packs nine calories,'' he noted. "The heavier you are, the higher your risk for breast cancer, especially after menopause.'' The study involved 61,471 women aged 40 through 76 who were questioned between 1987 and 1990 about their fat intake. During an average follow-up of 4.2 years, 674 cases of invasive breast cancer were diagnosed. Women who ingested at least 10 grams of monounsaturated fat daily -- about three-fourths of a tablespoon -- cut their risk of breast cancer in half. The results were similar to previous studies that looked specifically at olive oil, the main source of monounsaturated fat in Mediterranean diets. The authors, noting that olive oil consumption is very low in Sweden, say their study shows that it's the kind of fat rather than specifically olive oil that reduces the breast-cancer risk. Women who ate at least 5 grams daily of polyunsaturated fats, such as those found in safflower and corn oils, increased their breast-cancer risk by 69 percent. Polyunsaturated fats may "alter the risk of breast cancer by increasing the formation of free radicals that can damage DNA and promote tumor development,'' Wolk and colleagues wrote. Free radicals are dangerous byproducts that form when the body metabolizes oxygen. They are thought to produce cellular damage that can lead to cancer. Others have theorized that monounsaturated fats are less easily oxidized than polyunsaturates and that they contain antioxidant vitamins that soak up free radicals. Switching types of fat likely would be easier to swallow for most people than long-term reduction in total fat intake, the authors said.

Barnard, however, said cutting total fat intake should also be a goal for most Western societies in order to reduce incidence of many types of cancer as well as cardiovascular disease. PHOTO Lindo's Family Foods packer Elizabeth DeSilva lends a helping hand to her customers