New technologies and new studies are helping to confirm what we've long suspected: Exercise can reduce your risk of breast cancer by lowering estrogen levels in your body.
We're now beginning to understand how the process works. When you exercise, you produce more of the “good” molecules, or metabolites, that play a critical role in safely breaking down the estrogen in your system.
And apparently, age doesn't matter.
To better understand how exercise affects estrogen, researchers at the University of Minnesota monitored 600 young women over four months. Half the women did no exercise. The other half did 30 minutes of aerobics five times a week.
All the women provided urine samples to measure their estrogen and metabolite levels. The group that exercised showed a higher level of a metabolite called 2-OHE1 and lower levels of another, called 16alpha-OHE1. A high ratio of 2-OHE1 to 12alpha-OHE1 has been linked with a reduction in breast cancer risk.
“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 study author Mindy S. Kurzer, Ph.D. at the University of Minnesota.
A second study looked at older, postmenopausal women and employed wearable devices called “accelerometers” to help the women track their exercise activity. Here again, researchers tested urine samples, this time measuring two “parent” estrogens, as well as 13 different metabolites.
“This is the first study to consider the relationship between accelerometer-measured activity and a panel of estrogen metabolites measured in urine,” said study author Cher Dallal, Ph.D., of the National Cancer Institute. “We hoped by using direct measures to examine this relationship that we could improve our knowledge of how these factors may influence cancer risk among postmenopausal women.”
Leslie Bernstein, Ph.D., City of Hope's director of the Division of Cancer Etiology, agrees: “This is the first time we have strong evidence that measured physical activity reduces hormone levels. It helps us understand what’s going on and how it’s working.”
So, from two directions, the same message. Want to cut your risk of breast cancer? Get moving!