How Exercise Can Lower Your Breast Cancer Risk

Cecile LaRiviere

Posted on May 14 2013

Regular exercise is known to lower a woman's risk of developing breast cancer. This has been well documented in a number of studies, but the way in which exercise provides protection has not been clearly understood. Exciting new research released recently has revealed how exercise can guard against breast cancer: vigorous exercise has a positive effect on how estrogen is broken down (metabolized) in the body.

It is estimated that about 80 percent of breast cancer tumours are estrogen-dependent, meaning they require estrogen to grow. Certain estrogen metabolites, or breakdown products, can speed tumour growth, while others are relatively benign and possibly protective.

In this new study, researchers recruited more than 300 healthy, yet sedentary (in active), women from 18 to 35 years old. Roughly half of them were randomly assigned to a vigorous exercise program of 30 minutes a day for five days a week. The remaining women served as a control group and continued with their sedentary lifestyle. Urine samples were collected from the participants so researchers could measure levels of estrogen and estrogen metabolites.

The researchers looked at the ratio of two specific metabolites: 2-hydroxyestrone (2-OHE1) and 16 alpha-hydroxyestrone (16-alpha-OHE1). The metabolite 2-OHE1 is relatively benign with a weak estrogen effect while 16-alpha-OHE1 is considered potentially carcinogenic. Several previous studies have found that as urinary levels of 2-OHE1 increase and levels of 16-alpha-OHE1 decrease, the risk for breast cancer decreases. The ratio of these metabolites, 2OHE1 to 16-alpha-OHE1, is known as the estrogen metabolite ratio (EMR).

After four months, the women in the vigorous exercise group had a much more favourable ratio of these two metabolites than the sedentary participants, according to the study published in the journal Cancer Epidemiology, Biomarkers & Prevention.

This study adds to the body of evidence supporting the value of strategies that can improve a woman's EMR. A previous study conducted on femMED's Breast Health formula found that use of this supplement for a month period of time had a positive effect on EMR. This was the first time a supplement had been studied for its potential protective effects against the biomarkers associated with breast cancer.

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