We usually hear about gut health and vaginal health as separate things, but they’re actually in constant conversation. They share microbes, swap signals, and even influence each other through hormones and the immune system.
This relationship, known as the gut–vaginal axis, plays a bigger role in your well-being than you may realize. We’re exploring how the gut and vaginal microbiomes interact and how you can support both with simple, everyday choices.
Your gut and vagina are talking—and it matters
The gut-vaginal axis refers to the relationship between your gut and vaginal microbiome. These aren't just separate systems doing their own thing. They're connected through shared microbes, circulating metabolites, and immune and hormonal crosstalk [1].
These gut and vaginal microbiomes communicate through several channels:
Microbial sharing. Some microbial strains exist in both places.
Metabolite exchange. Gut microbes produce compounds that travel through your bloodstream and may reach your vagina.
Hormonal signaling. Some gut bacteria help regulate estrogen levels, which in turn impact vaginal tissue and microbiome balance.
Immune signaling. Your body’s immune system connects the dots between what happens in your gut and your reproductive tract.
How gut bacteria can reach the vaginal tract
Research shows that some microbes, including beneficial ones like Bifidobacterium, are genetically identical in both the gut and vagina in the same person [2]. This suggests that microbes may move between these two sites, possibly from the gut to the vagina, and especially from mom to baby during birth.
Part of this connection is physical: the vaginal opening and the anus are located very close together. That means microbes from the gut can more easily migrate to the vaginal and urinary tracts. This kind of cross-contamination doesn’t always cause problems; some shared microbes are beneficial, but it also opens the door for disruptive bacteria.
For example, disruptive bacteria linked to bacterial vaginosis and Group B Streptococcus (GBS) have been found in both the gut and vagina [3], [4]. GBS can live harmlessly in the gut but migrate to the vaginal tract, where it poses a small risk during vaginal delivery by potentially infecting the newborn. Similarly, certain strains of E. coli—often originating in the gut—can travel to the urinary tract and cause infections [5]. These suggest that the gut may serve as a source, or reservoir, for microbes that influence vaginal and urinary health.
Several studies found that taking oral Lactobacillus probiotics can help improve vaginal health and reduce symptoms of bacterial vaginosis, even when those probiotic strains don’t directly colonize the vagina [6], [7]. This suggests that oral probiotics may indirectly support the vaginal microbiome, possibly by first improving gut health, and then influencing vaginal conditions through immune, metabolic, or microbial signaling along the gut-vaginal axis.
Metabolites: the tiny messengers in your bloodstream
Your gut microbiome doesn’t just sit around. It works hard to break down food and produce helpful compounds, including short-chain fatty acids (SCFAs). These SCFAs usually help reduce inflammation and protect gut health [8].
But here’s the twist: SCFAs may not always be friendly in the vagina. In some cases, they may promote vaginal inflammation and contribute to microbial imbalance [9].
That’s because not all SCFAs are created equal. In a healthy vaginal microbiome, lactic acid (produced by Lactobacillus) is the star player. It helps keep the pH low (around 3.5), supports a healthy immune response, and protects against infections. But when lactic acid levels drop, as in bacterial vaginosis (BV), other SCFAs like acetate, propionate, and succinate become more dominant [10]. These aren’t as protective. A laboratory study showed that high levels of SCFAs can trigger inflammation in vaginal cells and disrupt immune signaling [11].
What’s more, because SCFAs produced in the gut can enter the bloodstream and reach different organs, imbalances in SCFA production may also influence the vaginal environment.
Enter the estrobolome: your hormone-regulating microbiome
One fascinating part of the gut-vaginal connection is the estrobolome: a collection of gut bacteria that help regulate estrogen levels in the body.
Estrogen plays a critical role in vaginal health, helping maintain a thick, glycogen-rich lining that feeds beneficial Lactobacillus species [12]. But to keep estrogen in balance, your body relies on the liver and gut working together. After estrogen is used, the liver packages it for removal, and the gut helps either eliminate or re-circulate it.
That’s where the estrobolome comes in. Certain gut bacteria produce an enzyme called β-glucuronidase, which can reactivate estrogen in the gut, allowing it to be reabsorbed into the bloodstream [13]. If this process is well-regulated, it helps maintain healthy estrogen levels. But if the gut microbiome is imbalanced (e.g., after antibiotics or due to a low-fiber diet), it can disrupt this process and lead to estrogen excess or deficiency.
This becomes especially relevant during menopause, when estrogen levels naturally decline and the vaginal lining becomes thinner and more sensitive. Supporting a healthy estrobolome during this transition may help ease some of the hormonal shifts and maintain better vaginal comfort and resilience.
In this way, your gut microbiome doesn’t just support digestion, it plays a key role in keeping your vaginal environment healthy by regulating hormones from the inside out.
How your immune system links gut and vaginal health
Beyond sharing microbes and signals, your immune system plays a crucial role in connecting your gut and vaginal microbiomes. One key player is a special type of antibody called immunoglobulin A (IgA), which is produced mainly in the small intestine. In the gut, IgA helps maintain balance by coating bacteria, supporting beneficial microbes while keeping harmful ones in check [14]. This selective coating encourages a healthy microbial community and protects the gut lining.
But IgA doesn’t just stay in the gut. Scientists think that the small intestine trains immune cells to recognize beneficial bacteria like Lactobacillus. These immune cells then travel from the gut to the vagina, where they produce IgA that specifically targets Lactobacillus [15]. This IgA coating helps these good bacteria stick to the vaginal lining and grow, promoting a stable and healthy vaginal environment.
This immune connection is an important way your gut can influence vaginal health, showing how deeply these two microbial ecosystems are linked.
The gut microbiome’s role in fertility and reproductive health
The gut microbiome doesn’t just influence vaginal health, it also seems to play a crucial part in fertility and conditions like polycystic ovary syndrome (PCOS) and endometriosis [16], [17]. Scientists think that gut imbalances can lead to chronic inflammation and hormonal disruptions that affect the entire reproductive system, including ovulation and uterine health.
Some studies suggest that an overactive estrobolome could lead to higher levels of circulating estrogen, which in turn would promote the growth of endometrial lesions. But not all studies agree, and more research is needed [18], [19].
At the same time, increased gut permeability or low production of anti-inflammatory compounds like butyrate may allow inflammatory agents, like lipopolysaccharide (LPS), to escape into the bloodstream, potentially triggering immune responses in the pelvic region that contribute to pain or disease progression [20].
How to support a healthy gut-vaginal axis
Supporting a healthy gut-vaginal connection starts with everyday habits that gently nourish both microbiomes and help keep them in balance.
Incorporate more fiber-rich, plant-based foods. Whole grains, legumes, fruits, and vegetables are natural sources of prebiotics that feed your beneficial gut bacteria, helping support microbial diversity and keeping inflammation and the estrobolome in check.
Limit ultra-processed foods when possible. Diets high in processed snacks, sugary drinks, and additives negatively impact your gut microbiome, which can have downstream effects on vaginal health as well [21]. Choosing more whole, minimally processed foods supports a more resilient and balanced microbiome.
Be mindful of antibiotic use. While sometimes necessary, antibiotics can disrupt the gut and vaginal microbiome. If you’ve recently taken antibiotics or plan to take them, consider supporting recovery with targeted probiotics or prebiotic-rich foods.
Stay aware of hormonal shifts. Life stages like hormonal contraceptive use, postpartum, and menopause can influence the balance of your microbiomes. Tuning into your body and adjusting your diet or supplement routine can make a difference.
Understanding your gut and vaginal microbiomes can give you powerful insight into how these systems work together to shape your health. Knowing whether they’re in balance or need a little support can help you choose the right probiotics, supplements, and foods for your body. It’s a more personal, science-backed way to support your well-being with confidence.
