You’re choosing groceries when you spot another product promising to “balance hormones” by improving your gut. The connection sounds plausible. Your digestive tract really does make hormone signals, and its bacteria take part in several chemical pathways.
In this article
Understanding those connections can help you make sense of the claims. Some describe everyday digestive biology. Others draw on early research that still has questions to answer. Here’s where the evidence stands and how to care for your digestion in the meantime.
Your gut sends hormone signals
Cells in the lining of your stomach and small intestine release hormones that help coordinate digestion and signal hunger or fullness. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) explains that these signals work with nerves to guide the digestive process.
The microbes living in your digestive tract help break down food too. Your own cells and these microbes have different jobs. A finding about a gut hormone does not automatically tell us what a probiotic will do. Our guide to food and hormones looks at the wider picture.
Gut serotonin and the brain
Much of the body’s serotonin is made in the digestive tract, where it helps regulate functions such as intestinal movement. In a 2015 Caltech study, researchers found that particular gut bacteria promoted serotonin production by gut cells in mice. They studied intestinal and blood serotonin and related functions, rather than showing that a probiotic improves mood in people.
Serotonin in the gut and blood is largely separate from serotonin in the brain. It does not readily cross the blood-brain barrier, as this review of serotonin biology explains. Gut-brain communication involves several pathways, so a large amount of gut serotonin cannot be translated into a promise of better mood. See our serotonin guide for its different roles.
The estrobolome and estrogen recycling
The liver attaches chemical groups to estrogens as part of processing them for removal. Some of these compounds enter the gut through bile. Enzymes made by certain bacteria can remove those groups, allowing some estrogen to be reabsorbed into circulation.
The American Society for Microbiology describes the collection of microbial genes involved in estrogen metabolism as the estrobolome. One of the enzymes involved is beta-glucuronidase. Think of the pathway as a recycling route, with some processed estrogen returning to circulation while other material leaves the body.
A small cross-sectional study found associations between gut microbes and estrogen measurements in men and postmenopausal women. It did not find the same associations in the premenopausal group. A snapshot like this can identify links, but it cannot show that changing someone’s gut bacteria will treat period symptoms or menopause symptoms.
How to read probiotic claims
Probiotics are live microorganisms used with the intention of providing a health benefit. Their effects depend on the organism and the condition being studied. The National Center for Complementary and Integrative Health (NCCIH) reports promising findings for some specific uses, alongside continuing uncertainty about which products help and who benefits.
A result for a particular strain and digestive condition cannot establish that a different product will improve estrogen metabolism or mood. If a label promises “hormone balance,” ask what outcome was measured in people, which exact product was tested, and whether the study fits your situation.
People with serious illness or a weakened immune system face higher risks from probiotics and should discuss them with their care team.
What you can do
- Start with foods you enjoy. Fruit, vegetables, beans, lentils, and whole grains can provide fiber. If constipation is an issue, MedlinePlus suggests adding fiber gradually because a sudden increase can cause gas and bloating. For example, try a small addition of beans to a familiar soup and notice how you feel.
- Ask about symptoms before buying a supplement. Bring a note of your bowel pattern, discomfort, medicines, and any changes you’ve noticed. A specific question makes it easier to discuss the options.
- Check the outcome behind a claim. A change in a stool test or a bacterial enzyme is different from a demonstrated improvement in symptoms. Look for the result that matters to you.
- Discuss a probiotic with your clinician. Ask whether there is evidence for the specific product and purpose you have in mind, especially if you have a health condition.
When to talk to a doctor
Arrange an assessment for ongoing or recurring digestive symptoms that affect daily life. If symptoms vary with your menstrual cycle, mention that pattern too.
For constipation accompanied by blood in the stool, constant abdominal pain, vomiting, inability to pass gas, or unexplained weight loss, NIDDK advises seeing a doctor right away. Give these symptoms priority over trying another gut-health product.
Frequently asked questions
Can the gut affect hormones?
Yes. The digestive tract makes hormone signals involved in hunger, fullness, and digestion. Researchers also study how gut microbes process hormones such as estrogen.
What is the estrobolome?
It is a name for microbial genes involved in estrogen metabolism. Some bacterial enzymes can help processed estrogen become available for reabsorption.
Can probiotics balance estrogen?
The pathways being studied do not establish a probiotic treatment for your estrogen level or symptoms. Ask about evidence for the exact product and clinical outcome.
Does making serotonin in the gut improve mood?
Gut serotonin has important local and peripheral jobs. The mouse study described here does not establish a mood benefit from changing the human microbiome, and gut serotonin does not readily enter the brain.
