Menopause, Estrogen, Gut Microbes & A Link to 5 Common Diseases


In the scientific publication, “Influence of Oral and Gut Microbiota in the Health of Menopausal Women,” (2017) in the 8th volume of Frontiers in Microbiology, authors Vieira, Castelo, Ribeiro and Ferreira explain how estrogen levels affect which microbes grow in the reproductive and gastrointestinal tract. This has a direct impact on rates of certain diseases commonly found in the post-menopausal female. This is a summary and interpretation of their findings.

The beautiful life of a female involves two important changes in estrogen levels: menarche and menopause. Menarche occurs during adolescence and marks the onset of menstruation and potential reproduction. The second change is during menopause, when menstruation ends and the ovaries become non-reproductive. Estrogen has a huge impact on her physical wellness, emotions, memory, sensitivity to pain, and even the microbes that grow in her reproductive and gastrointestinal tract.

For years, the medical community has known that there are differences in the rates of autoimmune diseases between men and women and even pre- and post-menopausal women. Although we have known about the impact of estrogen, the role of the natural microbes living in the female body is just starting to reveal itself. We now know that estrogen levels impact which microbes grow in the mouth, the gut and the reproductive tract (possibly other locations, as well). This has an impact on Periodontitis, Autoimmune Disease, Type I Diabetes, Osteoporosis and even Breast Cancer.

A common complaint of post-menopausal women is oral dryness and tooth loss. It is more common to see higher rates of bone loss, candidiasis, gingivitis and periodontitis in this population. Periodontitis is a result of long-term inflammation in the gums. It also comes with an increase in the levels of “gram-negative” bacteria in the mouth (note that gram-negative bacteria tend to be more inflammatory). Interestingly, a study shows that post-menopausal women undergoing treatment with estrogen replacement therapy do not suffer from periodontitis as much as those without the therapy. This fact has lead scientists to ask what impact is the estrogen having? Does it somehow affect the microbes living in the mouth? Currently, studies are underway to determine if pre- and probiotics can treat oral diseases like periodontitis. It is believed that what is growing in the gut affects what is growing in the mouth and vice-versa.

Autoimmune disease results from the body’s own immune system attacking self. It has now been shown that dysbiosis (or, the “unhealthy state”) of the gut microbiota is the cause of autoimmune disease and not just a by-product of it. Studies are now considering the impact of the presence or absence of estrogen on gut microbes. Autoimmune diseases such as Systemic lupus erythematosus (Lupus), Sjogren’s syndrome and Rheumatoid arthritis more often affect women than men. Interesting to note, asthma commonly begins after menarche in women. So far, mouse studies have shown that the interactions between microbes, female hormones and the immune system are involved in the development of autoimmune diseases including Rheumatoid arthritis and Diabetes Type I.

Type I Diabetes, or juvenile diabetes, has an onset in childhood or early adulthood. It is a disease where the body does not produce insulin, a hormone that takes glucose from the blood and puts it into cells. In mouse studies, the non-obese diabetic (NOD) mouse undergoes an immune attack and destruction of the pancreatic beta cells that make insulin, thus, stopping all insulin production. The rate of this occurring is strongly female, with a 2:1 female to male status in the mouse model. Estrogen must be involved, right? Also, microbes must be involved because the elimination of gut microbes in these mice resulted in no gender difference in the rates of Diabetes. Even more evidence is that castrated male mice show similar gut microbes and rates of Diabetes to the female mice.

Bone loss increases in post-menopausal women. This is common knowledge. What is new is the idea that probiotic therapy is showing promise in both mouse and human models. A study of 20 post-menopausal women resulted in higher blood serum calcium levels when the probiotic, Lactobacillus helveticus, was added to the diet. In mice, the addition of the probiotic, Lactobacillus reuteri, protected from bone loss. Also in mice, the probiotic, Lactobacillus rhamnosus, helped to heal “leaky gut,” reduced inflammation and protected from bone loss.

This part gets very interesting. Gut microbes may influence the risk of breast cancer! I need to share with you that other studies (not this referenced publication) have shown that certain microbes in the gut are able to snip off the sugar compound from estrogen as it passes through the gut. The microbe “eats” the sugar and the naked estrogen is absorbed back into the blood instead of being eliminated, as it was supposed to be. The presence of this bad microbe is the switch for what will happen to the estrogen. High estrogen levels in the body have been found to increase breast cancer risk. This review paper notes a study showing that postmenopausal women with breast cancer have gut dysbiosis (unhealthy state) and low species diversity (not healthy). Having many different types of gut microbes (healthy gut) affects estrogen levels in the body and possibly lowers the risk for estrogen-related diseases. A diet rich in a rainbow of fruits and vegetables and low in sugar and processed foods has been shown to promote healthy gut microbes.

If you are interested in reading more, this article is based on the following publication:
Vieira, A, Castelo, P, Ribeiro, D and Ferreira, C. (2017) Influence of Oral and Gut Microbiota in the Health of Menopausal Women. Frontiers in Microbiology, 8(1884). Retrieved from