Fiber Curbs Estrogen in Breast Cancer Patients

A high-fiber low-fat diet reduces blood levels of estrogen in women with breast cancer, researchers report. This may help keep the disease in check, as breast cancers are sometimes driven by female hormones.

As lead investigator Dr. Cheryl L. Rock told Reuters Health, “The results of this study show that diet composition, especially increased fiber intake, may affect levels of reproductive steroid hormones in women. Previous studies that have examined change in diet composition and steroid hormone levels were confounded by concurrent weight loss.” As reported in the Journal of Clinical Oncology, Dr. Rock of the University of California, San Diego, and colleagues studied 291 women at an average of 2 years after a diagnosis of breast cancer. They were divided into one group given dietary advice for cancer prevention and another comparison group given general dietary guidelines. Those in the cancer-prevention diet group were advised to have a high intake of vegetables and fruit and a low intake of fat. They also attended 12 cooking classes, had telephone counseling and were given relevant printed materials. Those in the comparison group attended four cooking classes not aimed at cancer prevention and were given standard government dietary materials. At one-year follow-up, the high-fiber, low-fat group reported a significantly reduced intake of energy from fat (21 percent) compared to those in the comparison group (28 percent). They also had a significantly higher intake of fiber (29 grams per day) than the comparison group (22 grams per day). No significant weight loss was seen in either group. In the high-fiber, low-fat group there was a significant drop in estrogen, while in the comparison group there was a slight increase. The change in fiber intake had the most effect on estrogen levels. “These findings,” Rock concluded, “illustrate one mechanism by which diet may affect risk for breast cancer.” Also, she added, “these observations may be relevant to other health concerns in women in which reproductive steroid hormones play a role, such as problems with ovulatory function and infertility.” (SOURCE: Journal of Clinical Oncology: Reuters Health News: David Douglas: Oncolink: July 2004.)