The Hormone-Gut Connection Every Woman Should Know

May 23

Ever felt bloated before your period, or noticed your digestion shifts with your cycle? It’s not just in your head, it’s in your gut. Research into the gut microbiome and its connection to overall health has gained significant traction in recent years, including findings around the connection between digestive health and hormones, which shapes everything from mood to metabolism to menstrual symptoms. In this post, we’ll explore the hormone-gut connection and how it impacts your overall health.

What is the gut microbiome?

The gut microbiome is the largest ecosystem in the human body, home to trillions of bacteria, fungi, and other microbes. Like your fingerprints, it’s completely unique to you and is shaped by genetics, diet, and other environmental factors.

Most people think gut bacteria just help with digestion, but they also:

Break down fibers and carbs you can’t digest on your own
Produce essential vitamins like B1, B9, B12, and K
Support your immune system (approximately 80% of your immune cells live in your gut)
Generate short-chain fatty acids that help protect your gut barrier, preventing bacteria and bacterial toxins inside from escaping into your bloodstream.
Affects your nervous system via the gut-brain axis, the network of nerves, neurons, and neurotransmitters that run through your GI tract. Certain bacteria can produce or stimulate the production of neurotransmitters like serotonin that send chemical signals to your brain.

“Dysbiosis” refers to an unbalanced or unhealthy gut, and it means:

A loss of good bacteria
Overgrowth of potentially bad bacteria
Lack of bacterial diversity

Your gut microbiome is affected by many factors including diet, exposure to environmental toxins such as alcohol, tobacco, and pollutants, diversity of bacteria, and the regularity of bowel movements. The movement of food and waste through your GI system helps distribute microbes to different places, but if it’s too fast, these microbes don’t have time to settle or do their jobs, and if it’s too slow, they can overeat and overgrow.

Gut and Hormones: A Two-Way Street

Your gut not only supports digestive and immune health, it’s also the body’s largest endocrine organ. Specialized cells in your gut lining interact with the endocrine system, helping to regulate hormone levels and maintain balance.

Two key reproductive hormones estrogen and progesterone have a major influence on gut function, and because their levels fluctuate throughout the menstrual cycle, so does digestion. During the follicular phase (days 5-14), estrogen levels increase, which speeds up digestion, sometimes resulting in looser stools during the follicular and ovulatory phases. Progesterone levels increase during the luteal phase, peaking around day 21 of the 28 day cycle. Progesterone slows digestion, often causing bloating, gas, and constipation in the luteal phase.

For menopausal women, declining estrogen and progesterone can slow down gut motility, increasing symptoms like bloating, constipation, and weight gain. At the same time, the composition of the gut microbiome changes, exacerbating digestive discomfort and systemic inflammation.

What Is the Estrobolome, and Why It Matters

The estrobolome, a subset of your gut microbiome, is a collection of bacteria that metabolize estrogen and helps maintain healthy estrogen levels. An imbalanced estrobolome can lead to estrogen dominance, which is associated with:

Painful periods
Fibroids - non-cancerous growths or tumors in the uterus
Weight gain
Infertility
Higher risk of estrogen-dependent cancers like breast, ovarian, and uterine cancer

Constipation makes this worse because it prevents the body from being able to get rid of excess estrogen. Chronic inflammation in the gut is caused by a myriad of factors, including genetics, lifestyle, environmental exposure, or certain diseases. Regardless of the cause, this inflammation can also disrupt estrogen, thyroid, and stress hormones, contributing to adrenal, reproductive issues, and thyroid dysfunction.

Hormone-related conditions linked to gut health

Unfortunately, it’s not uncommon for women to experience hormone-related conditions linked to gut health, some of which have been on the rise in recent years, particularly Polycystic Ovary Syndrome (PCOS). Increasing research shows that the gut microbiome plays an active role in both the development and progression of many common hormone disorders in women.

PCOS affects 5-10% of women in the U.S., and symptoms include irregular periods, ovarian cysts, and high androgens (a group of steroid hormones that promote the development and maintenance of male characteristics, such as testosterone). PCOS has received growing attention as its prevalence continues to rise, with emerging research highlighting the gut’s role in its development. Women with PCOS often show reduced microbial diversity and altered gut composition compared to those without the condition.

A review by the Institute for Functional Medicine (IFM) explains that these changes in the microbiome are closely tied to:

Reduced gut microbial diversity
Chronic inflammation
Insulin resistance

While there is no “cure” for PCOS, its symptoms can be managed through diet, exercise, and some medications. However, if PCOS is left untreated, it can lead to long-term health problems such as infertility, increased risk of diabetes, heart disease, and endometrial cancer, as well as psychological issues like depression and anxiety.

Poor gut health can also lead to thyroid disorders. A slowed digestive system can interfere with the absorption of nutrients such as iodine, selenium, and zinc, which are critical for thyroid hormone production. In response, thyroid hormone imbalances slow down gut motility, increasing the risk for constipation, which in turn may worsen estrogen clearance and overall hormonal balance. This creates a vicious cycle of dysfunction that is difficult to disrupt once it begins.

See Part 2 of this post: How Restrictive Dieting Wrecks Your Gut and Hormones