High-Fat Diet Not Associated With Increased Estrogen in Postmenopausal Women

January 1, 2001

There is no evidence that a high-fat diet predisposes older women to breast cancer, report researchers from Harvard Medical School. It has long been thought that dietary fat can increase production of sex hormones, including estrogen, and

There is no evidence that a high-fat diet predisposesolder women to breast cancer, report researchersfrom Harvard Medical School. It has long been thought that dietary fat canincrease production of sex hormones, including estrogen, and thus put women(especially older women) at risk for breast cancer. This study in 381postmenopausal women, however, revealed just the opposite. The researchers foundthat women in the study who ate less fat than is typical among US women actuallyhad higher levels of estrogen in their blood, making it unlikely that eating alow-fat diet will lead to lower levels of estrogen.

"This is good news for women," said the study’s leadauthor, Michelle Holmes, MD, DrPH, assistant professor of medicine at HarvardMedical School. "It’s one less thing they need to worry about if they areconcerned about breast cancer. We found no evidence that higher fat intake isassociated with higher levels of any reproductive hormones in this group ofpostmenopausal women."

Lower Fat Intake Leads to Higher Hormone Levels

Dr. Holmes added that lowering fat intake to reduce hormonelevels, and thus the risk of breast cancer, probably is not a useful strategy."It does not seem likely that eating a low-fat diet in midlife can lowerhormone production," said Dr. Holmes.

The research team took blood samples from study participants tomeasure the amount of hormones present in their blood. Those hormones includedestradiol as well as "male" hormones such as testosterone. Researchersalso estimated the different kinds of fat the women ate, based on a food surveyconducted twice during the 4-year study. None of the women were using hormonereplacement therapy.

The researchers found that as women increased the amount of fatin their diets, the levels of six hormones declined. The study results werepublished in a recent issue of the Journal of Clinical Oncology (18:3668-3676,2000).