Intermittent calorie restriction may lower the risk of developing breast cancer better than full-time dieting, according to a new study.

To determine the influence of periodic dieting on breast cancer, researchers at the Hormel Institute of the University of Minnesota examined three sets of mice.

The mice predisposed to developing breast tumors were put on different diets: unlimited eating, intermittently cutting calories by 25 percent, or permanently reducing caloric intake by 25 percent.

The research found that those on the intermittent diet fared best, with only 9 percent developing mammary tumors compared to 35 percent of those chronically restricted and 71 percent of those that ate all they wanted.

Findings of the research were published in the Aug. issue of Cancer Prevention Research.

Periodic dieting may reduce the secretion of insulin-like growth factor 1 (IGF-1), a hormone linked to the promotion of breast cancer, according to the research.

"Understanding how calorie restriction provides protection against the development of mammary tumors should help us identify pathways that could be targeted for chemoprevention studies," study author Margot P. Cleary said.

"Further identification of serum factors that are involved in tumor development would possibly provide a way to identify at-risk individuals and target interventions to these people," she said.

This study "contributes to accumulating evidence that caloric restriction acts by altering hormone levels rather than by directly starving cancers of energy," Dr. Michael Pollak, a professor of oncology at McGill University in Montreal, wrote in an accompanying editorial.

"In particular, lower levels of insulin are associated with reduced food intake, and this may be protective," he said.

Finding ways to reduce IGF-1 and insulin in the body, medically or though diet and exercise, should be further investigated, Pollak suggested.

(Xinhua News Agency August 5, 2009)