Study refines diet's link to breast cancer.

Study refines diet's link to breast cancer

Research has linked some cancers -- especially breast cancer -- to diet, but studies have offered conflicting data on which foods increase risk most. For breast cancer, fats and/or calories have been implicated most often. A new study of women in northwestern Italy's province of Vercelli not only confirms that general link, but also points a finger at saturated fats and animal proteins as the most potent risk factors.

Explains Paolo toniolo, an epidemiologist at New York (City) University Medical Center, "We studied Italian women because this population [is very homogeneous] and has a much larger variation in dietary habits" than other groups that have been studied -- such as U.S. nurses (SN: 1/3/87, p. 4). Together with colleagues at a Turin hospital and the International Agency for Research on Cancer in Lyon, France, he compared the diets of 250 breast-cancer patients against those of 499 healthy women of about the same age -- based on questionnaires of foods and portions eaten.

Consumption of carbohydrates (such as starches) and vegetable fats (like olive oil) differed little between the two groups. Somewhat higher protein and fact consumption typical of the breast-cancer group was due entirely to higher consumption of meat and dairy products. In fact, the biggest difference between groups was that women with breast cancer tended to consume considerably more milk, high-fat cheese and butter.

Breast-cancer risk was highest -- three times normal for this population -- among women who consumed about half their calories as fat, 13 to 23 percent of their calories as saturated fat, and 8 to 20 percent of their calories as animal protein, according to a report in the Feb. 15 JOURNAL OF THE NATIONAL CANCER INSTITUTE. Moreover, limiting total fat to less than 30 percent of calories, saturated fat to less than 10 percent of calories or animal protein to less than 6 percent of calories may substantially reduce risk -- below what has been considered normal. Vercelli women consuming such a diet had just half the breast-cancer risk typical for this region.

This suggests that independent of calories, animal fats and proteins increase breast-cancer risk, observes David Kritchevsky, of the Wistar Institute in Philadelphia. That's interesting, he says, because "in our animal experiments, calories seem to be more important than what contributes them."