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Calorie Restriction May Reduce Risk of Breast Cancer by Pat McCaffrey, The Harvard FOCUS, April 30, 2004 Research has shown that eating less can reduce the risk of breast cancer--if you're a mouse. But while calorie restriction may make rodents and worms live longer, healthier lives, no one knows its effects on human health. It is hard to ask the question, since a protocol of starvation is unlikely to pass the human subjects research committee or to be very popular with research volunteers. By investigating a group of more than 7,000 Swedish women who had been hospitalized for anorexia, researchers were able to measure for the first time the effect of severe calorie restriction on breast cancer incidence in women. They concluded that for humans, calorie restriction is associated with decreased odds of getting breast cancer. "We studied women with a considerably reduced calorie intake and found that overall they had half the risk of breast cancer compared with the general population," said Karin Michels, lead author of the study, published in The Journal of the American Medical Association on March 10. Michels is an associate professor of epidemiology at HSPH and of obstetrics, gynecology and reproductiive biology at HMS. The biggest decrease in breast cancer risk, 76 percent, was observed for women who had been anorexic, but went on to have a child. Women who never experienced pregnancy had a 23 percent reduction in risk. Michels worked with Anders Ekbom, HSPH adjunct professor of epidemiology, to scrutinize the health records of women who were hospitalized for anorexia in Sweden between 1965 and 1998. The researchers cross-referenced cancer registry records to determine how many women developed breast cancer and fertility records to see whether the women had ever had children. Though diet has been implicated in developing breast cancer, Michels said that studies show no striking correlatiion with any single dietary component. Her study suggests that total caloric intake may be more important than any particular food or nutrient. "We are not trying to give the message that women should be anorexic," Michels said. "Anorexia nervosa is a severe and life-threatening disease. We are using anorexia as a model to study caloric restriction in women, which we would not be able to do otherwise." According to Michels, because anorexia usually happens early in life (most women in the study were younger than 19 at the time of hospitalization), the study supports the idea that early life experiences may be important to a woman's chance of developing premenopausal breast cancer. |