How microorganisms control sex hormones

The microbiome—a complex community of trillions of bacteria and viruses—plays a crucial role in many aspects of our health, from digestion to the immune system to brain function.

The microbiome is also closely linked to sex hormones and may thus play a crucial role in the development of diseases such as ovarian cancer, osteoporosis or polycystic ovary syndrome.

The fascinating connection between microbiome and hormones

Research shows that there is a bidirectional relationship between the gut microbiome and our sex hormones. This means that not only do hormones influence the composition of the microbiome, but the microbiome itself also actively regulates hormone levels in the body. This interaction is a remarkable example of just how profound the connection between microorganisms and humans is.

For example, it has been observed that the composition of the microbiome differs between men and women. Studies in mice and humans have shown that testosterone, estrogen, and progesterone—the primary sex hormones—can influence the diversity and composition of gut bacteria. Higher levels of certain bacterial families, such as Bacteroidaceae, have been found in men, while other bacterial groups dominate in women. This sex-specific composition is of enormous importance, as it could explain why certain diseases occur at different rates in men and women.

The female microbiome

In the following, the focus will be on the female microbiome and its correlation to hormone-related diseases in women, and how health can be taken into one’s own hands.

Women and osteoporosis

One example of a hormone-related disease is postmenopausal osteoporosis. This form of bone loss, which occurs in women after menopause, is triggered by a drop in estrogen levels.

Estrogen plays an important role in bone metabolism by inhibiting bone resorption and promoting bone formation. As estrogen levels decline, the activity of osteoclasts—which break down bone—increases, while the activity of osteoblasts—which build bone—decreases. This leads to an imbalance in which more bone is broken down than is formed, which reduces bone density and increases the risk of fractures.

Interestingly, the gut microbiome appears to play a key role in this process. Experiments on mice have shown that an imbalance in the microbiota accelerates bone loss.

Certain bacteria in the gut can modify inactive estrogen via special enzymes (beta-glucuronidase) so that it can be reactivated and reabsorbed into the bloodstream.

Overall, the diversity and balance of the microbiome are important for optimal hormone regulation. In cases of a significantly altered microbiome (dysbiosis), the intestinal barrier may also be compromised, allowing substances that trigger inflammation to enter the bloodstream. These inflammatory processes, in turn, ultimately lead to increased osteoclast activity and, consequently, to accelerated bone resorption.

A healthy and diverse microbiome can therefore stop or at least slow down bone loss. Taking specific probiotics could also open up entirely new avenues for the prevention and treatment of osteoporosis.

Women and polycystic ovary syndrome

Another exciting area of research is polycystic ovary syndrome (PCOS), a common hormonal disorder among women of childbearing age. Women with PCOS often experience irregular menstrual cycles, excess weight, and elevated levels of androgens, the male sex hormones. Recent research suggests that women with PCOS have significantly less diversity in their gut microbiome than healthy women. An imbalance in the gut microbiota could therefore contribute to the insulin resistance and elevated androgen levels that are characteristic of PCOS.

A healthy microbiome can also help here and alleviate the symptoms of PCOS.

Women and ovarian cancer

One of the most surprising findings is the possible link between the gut microbiome and ovarian cancer. Ovarian cancer is one of the deadliest gynecological cancers, and its exact causes are not yet fully understood. However, there is evidence suggesting that the microbiome may play a role in the development and progression of this disease. Bacteria can lead to an excessive increase in estrogen levels and thereby promote the growth of ovarian tumors. As explained above, this occurs through the reactivation of inactive estrogen.

This clearly shows that only a balanced level of estrogen is healthy for the body. While too much estrogen can promote ovarian tumors, too little estrogen, in turn, causes osteoporosis. This, in turn, requires a balanced state in the microbiome.

Furthermore, there is evidence that the gut microbiome may influence the effectiveness of chemotherapy drugs such as cyclophosphamide. In mice, an imbalance in the gut microbiota led to the treatment being less effective. This suggests that a healthy gut microbiota could contribute not only to prevention but also to improving cancer treatment.

We are in charge of our own destiny.

Although the focus here has been on the female microbiome, the same applies equally to men. Insights into the connection between the gut microbiome and sex hormones open up exciting new possibilities in medicine, as well as in self-directed preventive care. By understanding these complex interactions, it may be possible in principle to develop future therapies that target the modulation of the microbiome to correct hormonal imbalances and treat sex hormone-dependent diseases.

But it’s also particularly clear—and this is the really good news—that investing in your own microbiome, through sufficient exercise, a healthy diet, and stress-reducing activities, definitely pays off. This can help combat diseases or even prevent them altogether.

This allows anyone to break out of a passive role and instead take an active and successful approach to managing their health. (JS)

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Further reading/sources:

He S, Li H, Yu Z, Zhang F, Liang S, Liu H, Chen H, and Lü M (2021) The Gut Microbiome and Sex Hormone-
-Related Diseases. Front. Microbiol. 12:711137.
https://doi.org/10.3389/fmicb.2021.711137

Image material:

Header: © markin; www.depositphotos.com; Text: © katerynakon – www.depositphotos.com