Eating a high fat diet does not increase the production of hormones that bring a higher risk of breast cancer, according to a team of Harvard researchers.

"This is good news for women," said Dr. Michelle Holmes from Harvard Medical School in Boston, Massachusetts in a news release. "It's one less thing they need to worry about if they are concerned about breast cancer."

Scientists have suggested that a high fat diet would increase the levels of the female hormone estrogen, which has already been implicated in the development of breast cancer, the authors explain.

Holmes and associates compared hormone levels in 381 women and correlated them to the proportion of the calories in their diet came from fat.

Contrary to previous suggestions, women who consumed a higher fat diet seemed to have lower levels of estrogen than did women who consumed a lower fat diet, the authors report.

This proved especially true when the results were adjusted for the presence of obesity, according to the report in the November 1st Journal of Clinical Oncology. With this adjustment, each 5% increase in energy from fat brought a 2.3% decrease in estrogen level.

Therefore, the authors conclude, these results argue against the theory that high fat diets increase the level of estrogen and the risk of breast cancer.

As far as dieting to lower the risk of breast cancer, Holmes said, "It does not seem likely that eating a low-fat diet in mid-life can lower hormone production."

(From Journal of Clinical Oncology 2000;18:3668-3676)