Exercise may lower a woman’s risk for breast cancer. Guidelines recommend people get about 150 minutes of moderate exercise a week. Although more research is needed to confirm the underlying mechanisms driving the protective benefits of exercise, exercise is an easy way to encourage good health overall. Scientists from the University of Minnesota in St. Paul conducted a study of 391 inactive, healthy, premenopausal women whom they split into two groups.
They found that the 179 women in the intervention group, who received 30 minutes of moderate-to-vigorous exercise five times a week for over 16 weeks, showed changes in their estrogen metabolism that could explain the anti-cancer benefits of working out.“Ours is the first study to show that aerobic exercise influences the way our bodies break down estrogens to produce more of the ‘good’ metabolites that lower breast cancer risk,” said Mindy Kurzer, a professor in the Department of Food Science and Nutrition at the University of Minnesota in a statement.
The study, appears in Cancer Epidemiology. There was a 25% increase in the metabolite ratio 2-OHE1/16-alpha-OHE1, which has been linked to a lower breast cancer risk. More 2-OHE1 and less 16-alpha-OHE1 have been associated with a lower risk since 16-alpha-OHE1 is thought to encourage cancer cell growth. These changes were not seen in the control group of women who did not exercise over the study period. The findings give cancer researchers more insight into how exercise interacts with estrogen to reduce cancer risk. This is especially important since estrogen is a large contributing factor in breast cancer development.
Researchers at University of North Carolina studied more than 3,000 women between the ages 20 to 98: 1,504 women with breast cancer and 1,555 women without the disease who were participating in the Long Island Breast Cancer Study Project. They found that women who did any exercise at all had a 6% lower risk of breast cancer than sedentary women. However, women who had children and exercised about 10 to 19 hours each week either during their reproductive years or after menopause experienced a much greater benefit, with a 30% lower risk of breast cancer compared to women who exercised less or were inactive.