EXERCISE REDUCES BREAST CANCER RISK BY ALTERING ESTROGEN BREAKDOWN

Researchers have long noted a relationship between regular aerobic activity and lower breast cancer risk.  Why does activity decrease breast cancer rates?  Certainly regular activity helps to keep weight in check and extra weight is a risk factor for breast cancer.  Interestingly, a new study has uncovered another reason activity is seems to lower risk.  A recent clinical trial found that regular activity changes the way women's bodies metabolize estrogen.  Estrogen metabolites are known to influence breast cancer development and the researchers found that aerobic activity  increases certain estrogen metabolites that lower risk while also reducing other estrogen metabolites believed to increase risk.  This study is just one in a growing number pointing to the fact that regular activity has many subtle metabolic effects that have far reaching implications for our health beyond simply burning calories.

The study included 391 pre-menopausal inactive women.  They ranged in age from 18 to 30 and had BMI's ranging from 18 (slightly underweight) to 40 (obese).  Researchers randomly assigned half of the participants to remain inactive while the other half did 30 minutes of moderate-to-vigorous aerobic exercise five times a week for 16 weeks. Participants worked out on indoor machines such as treadmills and elliptical machines.  Researchers collected urine samples from women in both groups before and after completing the study. There were no significant changes in the estrogen metabolites of the women in the inactive control group but for the women in the exercise group, the levels of the beneficial estrogen metabolites had increased and the levels of  the harmful estrogen metabolites had declined.   

What to do:  Aim to do 30 minutes of cardiovascular activity 5 times per week.  This will help to reduce breast cancer risk as well as risk for heart disease, diabetes, and most other chronic diseases.  Other factors that reduce breast cancer risk include maintaining a healthy weight, limiting intake of unhealthy saturated fats, avoiding alcohol, consuming a diet rich in antioxidants (deep orange and dark green veggies seem especially beneficial), and maintaining a healthy vitamin D level (ask your doctor to check your vitamin D level and take a supplement if needed).

Adapted from articles available at:

http://www.nlm.nih.gov/medlineplus/news/fullstory_136635.html

http://www.medpagetoday.com/HematologyOncology/BreastCancer/38967

http://www.sciencedaily.com/releases/2013/05/130507061143.htm

Source:

Smith AJ, Phipps WR, Thomas W, Schmitz KH, Kurzer MS.  The effects of aerobic exercise on estrogen metabolism in healthy premenopausal women.  Cancer Epidemiol Biomarkers Prev. 2013 May;22(5):756-64. doi: 10.1158/1055-9965.EPI-12-1325.  Available at:  http://www.ncbi.nlm.nih.gov/pubmed/23652373?dopt=Abstract