There are many reasons why women take estrogen therapy as they approach menopause, from relieving related symptoms leading up to and following menopause to improving vaginal health and guarding against bone loss.

Just like other drugs, taking synthetic estrogen has an effect on the microbial makeup, balance and activity in a woman’s gut too.

Moreover, this activity may affect how a specific enzyme in the gut — B-glucuronidase (GUS) — metabolizes synthetic estrogens in the gut, according to recent findings from a University of Illinois study featured in Scientific Reports.

Scientists made this discovery while conducting tests on five groups of female mice treated with various estrogens either alone or with bazedoifene (an estrogen-receptor drug). These test animals also had their ovaries removed and were fed high-fat diets.

What does this discovery mean for women taking estrogen? Depending on a woman’s gut health, it could affect how efficiently her body metabolizes estrogen.

Although the overall diversity of these test animals didn’t change significantly, levels of some bacteria did decrease along with some associated with the GUS enzyme, including Akkermansia.

This finding was fascinating to researchers because this specific bacterial family is linked to anti-inflammatory properties in humans.

Results from some fecal samples in mice treated with estrogen and bazedoifene showed significantly lower levels of Akkermansia. On the other hand, animals with higher levels of Akkermansia had larger livers, more estrogen and gained more weight.

“Our findings indicate that clinicians might be able to manipulate the gut biome through probiotics to change the half-life and properties of estrogens so that long-term users obtain the therapeutic benefits of estrogen-replacement therapy without increasing their risks of reproductive cancers,” says Dr. Zeynep Madak-Erdogan, lead researcher and director of the University of Illinois’ Women’s Health, Hormones and Nutrition Lab.

Gut diversity + estrogen does matter

You may be skeptical that gut health has any bearing on a woman’s ability to metabolize estrogen and, after all, the University of Illinois study focuses on mice.

However, a 2014 study of postmenopausal women determined gut health — specifically gut diversity — does matter.

In fact, postmenopausal women whose gut health is diverse may be more able to break down estrogen, which could reduce their risks of breast cancer, according to the Journal of Clinical Endocrinology and Metabolism.

These findings were based on an analysis of urine and fecal samples taken from 60 postmenopausal women between ages 55-69 in Colorado with healthy mammograms.

“Our findings suggest a relationship between the diversity of the bacterial community in the gut, which theoretically can be altered with changes in diet or some medications, and future risk of developing breast cancer,” says Dr. James Goedert of the National Cancer Institute who worked on the study, according to a press release.

“But we are hopeful that because the microbiome can change the way the body processes estrogens, it may one day offer a target for breast cancer prevention.”

The takeaway from these studies, especially if you’re a woman taking estrogen, is that it’s important for women, young and not so young, who take estrogen to pay much closer attention to their gut health.

Fortunately, the best way to maintain a healthy mix of bacteria in your gut may be easier than you think. Taking a probiotic like EndoMune Advanced Probiotic with 10 strains of beneficial bacteria, plus a prebiotic (food for the bacteria in your gut), can do a world of good for your health, and how your body uses estrogen.