The gut microbiome influences women’s health beyond digestive symptoms

Key takeaways:

• The microbiome includes bacteria that metabolize estrogen and influence circulating estrogen levels.
• Symptoms of dysbiosis can include bloating, gas, nausea and constipation with or without diarrhea.

This is the first installment of the Healio | Women’s Health & OB/GYN Nourish to Flourish column, edited by Susan Weiner, MS, RDN, CDN, CDCES, FADCES. In future installments, Weiner and Healio will speak with experts to discuss the impact of food and nutrients on women’s health.

Susan Weiner

Susan Weiner, MS, RDN, CDN, CDDES, FADCES, talks with Audrey Fleck, MS, RDN, who specializes in integrative and functional nutrition for women, about how the gut microbiome influences general health and women’s hormonal health.

Weiner: How does a healthy gut microbiome relate to general health?

Fleck: Most of us know that the role of our digestive system is to break down the food we eat and obtain nutrients for our survival. You might also be familiar with how our bowel movements serve as a way to eliminate toxins and food that wasn’t digested. Now, growing research is telling us that our digestive system is much more complex and can impact our entire body via our gut microbiome.

Our gut microbiome is a collective of microorganisms — like bacteria, fungi and viruses — that live inside of our intestines, most residing in our colon. Nowadays, our microbiome is recognized as an active organ that modulates multiple functions of our body. It’s arguable that we wouldn’t exist as humans without our symbiotic relationship with our gut microbiota.

Gut microbiota interact with our immune system, most of it housed within the walls of our intestine. Gut microbiota help shape our immune response and modulate inflammatory processes, both inside the gastrointestinal tract and systemically inside the body.

When we eat, gut microbiota help digest food. In particular, certain types of fiber, known as prebiotics, are loved by gut microbiota. After bacteria consume dietary prebiotics, beneficial metabolites called postbiotics are produced. One postbiotic, butyrate, is a short-chain fatty acid that positively impacts our gut lining, where it supports healthy blood glucose metabolism, and crosses into our brain, where it positively impacts mood and cognition. Other postbiotics produced by our gut bacteria include many B vitamins (B1, B2, B3, B5, B6, folate and B12), vitamin K and some amino acids.

A hot topic when it comes to gut health is the gut-brain axis. Our gut and brain communicate via this axis. The gut-brain axis is like a two-lane highway where crosstalk can occur between our central nervous system and our gut’s very own nervous system, known as the enteric nervous system. Our gut microbiome influences the health of our brain and mood through production of neurotransmitters and other metabolites. Serotonin and gamma-aminobutyric acid (GABA) are two neurotransmitters produced by our gut bacteria that help to promote a calm mind and happy mood.

Finally, our gut microbiome nourishes the lining of our intestines to maintain a strong gut barrier, and in turn, prevent inflammation. If our intestinal lining becomes “leaky,” too permeable, our immune system gets activated and promotes chronic inflammation. This is how our gut can be a root cause for inflammation that impacts our entire body.

Weiner: How can someone know if their gut is healthy?

Fleck: Symptoms associated with digestion are a clue that your digestive system might not be working optimally or your gut microbiome may have an imbalance, referred to as gut dysbiosis. Symptoms can include bloating, gas, abdominal discomfort, nausea and constipation with or without loose stools or diarrhea.

But it’s possible to have chronic inflammation with no digestive symptoms. We are finding that any disease associated with inflammation is often linked to gut dysbiosis or leaky gut. Gut symptoms may be absent, but you might have anxiety, skin problems, an autoimmune disease or trouble with your weight. These can all be rooted in gut microbiome imbalances and a leaky gut.

In my practice, I take an approach that still aims toward improving digestion and balancing the gut microbiome even if digestive symptoms are not present. In functional medicine, specialized stool tests are utilized to capture your gut biome’s “fingerprint” and look at biomarkers to assess the health of your intestine and digestive function. Although these stool tests are not diagnostic, they can help with creating a targeted nutritional and supplement plan that aims to optimize digestion and restore balance to your gut biome.

Weiner: What aspects of women’s health can gut health influence, and how strong is current evidence for the associations?

Fleck: The gut microbiome can absolutely impact women’s health since it impacts estrogen and therefore plays a major influence on reproductive, cellular, heart and bone health.

We call the part of the microbiome that modulates women’s hormones, the estrobolome. The estrobolome includes a collection of bacteria that are capable of metabolizing estrogen and influence circulating estrogen levels as well as how much estrogen our body gets rid of.

The way our estrobolome does this is through producing an enzyme called beta-glucuronidase. Beta-glucuronidase is like a Pac-Man. It frees bound estrogen being deported out of our body via bowel movements and makes it available for reabsorption into our circulation. Gut dysbiosis can modulate estrogen in either direction, high or low, depending on what groups of bacteria are out of balance.

The microbiome also has a bidirectional modulating relationship with progesterone, testosterone and cortisol. As a result, an imbalance of our gut microbiome composition can influence several diseases and conditions, such as pregnancy complications, adverse pregnancy outcomes, polycystic ovary syndrome, endometriosis, bacterial vaginosis and cancer; however, research on the mechanisms is limited.

As far as current evidence, most studies reveal associations between altered gut microbial compositions and these reproductive diseases, though few have suggested cause and effect relationships. Research in this field is evolving.

References:

• He S, et al. Front Microbiol. 2021;doi:10.3389/fmicb.2021.711137.
• Qi X, et al. Gut Microbes. 2021;doi:10.1080/19490976.2021.1894070.
• Serino M, et al. Curr Cardiol Rep. 2014;doi:10.1007/s11886-014-0540-1.

For more information:

Audrey Fleck, MS, RDN, is a registered and licensed dietitian-nutritionist specializing in integrative and functional nutrition for women. She can be reached at Info@AudreyFleck.com.

Susan Weiner, MS, RDN, CDN, CDCES, FADCES, is the owner of Susan Weiner Nutrition PLLC and the Healio | Women’s Health & OB/GYN Nourish to Flourish column editor. She can be reached at susan@susanweinernutrition.com; X (Twitter): @susangweiner.