The Gut-Vagina Axis: Is There a Relationship Between Your Gut and Your Vaginal Microbiome?

The first “microbiome” you likely ever heard of was that of the gut. And while the gut microbiome owns the spotlight in popular culture, and in scientific research, microbial communities actually exist in every area of the human body that’s exposed to the outside world. Your skin, mouth, nose, and eyes all have a microbiome, and, of course, so does your vagina. 

As scientific researchers have learned more about the gut microbiome’s influential relationship with almost every other element in the body (from your hormones to your brain), increasing conversation and curiosity have emerged about the gut’s relationship to its downstairs neighbor: the vaginal microbiome. 

And it’s not just scientists. People with vaginas from around the world have begun to ask their doctors, the internet, and Evvy’s community and experts — is there a relationship between my gut and vaginal microbiome?

Thankfully, we’ve got some answers. Evvy’s Senior Scientist, Krystal Thomas-White, a microbial maven (with a PhD, no less), breaks down existing research on the gut-vagina axis and explains how you can use this information to better understand what’s up down there as it relates to your body. 

What is the gut-vagina axis?

As we learn more and more about the vaginal microbiome, researchers are beginning to understand that a connection exists between the gut microbiota and the vaginal microbiome. 

There are three different ways the gut microbiota can have an impact on your vaginal health: 

• The gut microbiome acts as a reservoir for pathogens that can disrupt your vaginal microbiome  
• Poor gut health causes systemic inflammation, including in the vagina  
• Your gut microbiome can change the levels of hormones, like estrogen which can affect the vaginal microbiome. 

Pathogens from your gut can travel into your vaginal microbiome 

Many of the pathogens we worry about disrupting the balance of your vaginal microbiota (i.e., Candida albicans, E. coli, Prevotella) get into the vagina by way of the gut. This is known as a reservoir — a place where a stable community of potentially harmful bacteria hangs out. Periodically those harmful microbes will colonize the vaginal microbiome (and then maybe even the bladder) and cause symptoms. 

We also know that Lactobacilli levels in the gut correlated with levels of vaginal Lactobacilli. So to put it simply, a healthy gut microbiota means your vagina will likely be in a protective state as well. 

This is the current hypothesis as to how taking an oral probiotic might help improve your vaginal symptoms. 

Oral probiotics do show promise, but they don’t work for everyone. One of the main problems is that there is very little evidence that something taken orally actually ends up in the vaginas of women. Or if they do, they are only found for short periods.

For our teeny-tiny bacteria, the gastrointestinal tract is huge. And traveling through it to reach the vagina would be kind of like us trying to walk across the U.S. or like Marlin trying to find Nemo in the vastness of the ocean. 

On the other hand, if the probiotics are taking up residence in your gut, then they’re actually changing the community of gut microbes. This could prevent communities of pathogens, like E. coli, from growing too large and therefore there are fewer E. coli to go on to colonize the vagina (or the bladder, if you're concerned about urinary tract infections). 

This explains the current hypothesis for many dietary interventions, like the Candida diet. The logic behind it is that changing your diet can change your gut microbiome which would make it less hospitable to yeast. And if yeast aren’t living in your gut, then they don't colonize the vagina, and you get fewer yeast infections. Ta-da! 

The science does back this up. One study found that patients with intestinal overgrowth of Candida did better when they paired diet changes with antifungals compared to those on antifungals alone. While this study shows that diet can change the gut levels of Candida, more work needs to be done on if diet can change levels of yeast in the vagina (or rates of recurrence). 

Oral antibiotics, gut health, and inflammation

The gut microbiome is in charge of training your immune system. A healthy gut = a healthy immune system. Therefore, inflammation around the gut microbiome could cause a change in inflammation throughout your whole body. Unfortunately, there isn’t much research into how this gut-microbiome-training of the immune system directly affects vaginal symptoms.  

We do know that taking oral antibiotics for urogenital infections (like bacterial vaginosis or urinary tract infections) will deplete bacteria in your gut as well as your vagina. And the loss of intestinal bacteria can affect your immune system. 

This is why it’s important to help recolonize your gut with good bacteria after taking antibiotics — you can do this by taking an oral probiotic. A probiotic can not only help with symptoms of nausea and gastrointestinal distress, but it will also help get your immune system back to a health-balanced state (known as homeostasis). 

Gut microbiome and hormone levels

Researchers are beginning to understand that the gut microbiome can influence the levels of estrogen circulating in your bloodstream. Why does this matter for vaginal health?

Estrogen is an essential hormone for many reasons, but it’s particularly important for vaginal health because it helps your body provide a food source for protective bacteria called Lactobacilli. 

Lactobacilli act as the local heroes of the vaginal microbiome, helping to keep your vaginal pH acidic. 

When estrogen levels go up (like in pregnancy), levels of Lactobacilli go up because there is an increase in their food source (called glycogen) in the vagina. When estrogen levels decrease (like with menopause), the food source decreases and so too do levels of Lactobacillus. Side note — it’s thought that this is why some people have cyclical symptoms because Lactobacilli levels change as your hormones change throughout the menstrual cycle. 

When estrogen is low, and therefore Lactobacilli are low, this creates a more optimal environment for pathogens to colonize because the vaginal microbiome is less protective. 

Circling back to the gut-vagina axis, a healthy and diverse gut microbiome can help keep estrogen levels higher because it can keep estrogen (otherwise marked for removal by the liver) in your system. This increases overall levels of circulating estrogen in the body, which works to provide a food source for the Lactobacilli in your vaginal microbiome. 

Wait, my gut microbiome can change my hormones? Yep, this is a really new discovery, and we are only starting to understand it. But here are the basics:

Normally, hormones exit your body when you pee. This helps your body maintain healthy levels of hormones in the bloodstream. The way your body does this is by adding a flag or marker to the estrogen molecule that tags it for waste disposal. This tagging process naturally occurs in the liver. You can think of the liver as the bouncer at a club making sure that only people with the correct wristband/stamp get in. This marker “or wristband” is called glucuronic acid. Estrogen molecules with glucuronic acid exit the body and ones without will be kept around. 

Certain bacteria in the gut microbiome can add or remove these tags on estrogen molecules. Your gut microbiome is the friends helping sneak people into the club by sharing wristbands. It has been shown that the presence of these molecules (called either β-glucuronidases or β-glucuronides) is directly related to the levels of circulating estrogen. 

That is how the gut microbiome can change the levels of circulating hormones. And an increase in estrogen in your system can improve your vaginal microbiome. 

Is my gut contributing to my vaginal symptoms? 

While there is sadly no two-in-one, gut-vagina axis microbiome test, there are a few things you can do to take care of your gut and vaginal microbiomes. 

First up, do a loving assessment of your diet. There’s no need to shame yourself or go cold turkey on your favorite foods, but do think about what you’re eating in a day and a week and make sure you’re getting enough vegetables, including those leafy greens. This is good for your health regardless of what’s up down there. 

If your primary concern is recurrent vaginal symptoms, it may be time to invest in a vaginal microbiome test like Evvy’s. Taking a microbiome test using metagenomic sequencing will not only reveal all bacteria and fungi in your vaginal microbiome but it will tell you their relative amounts and give you a full picture of your vaginal health, rather than just a snapshot. 

Additionally, before you start popping probiotics, a fast and simple way to improve your gut health, it’s important to know the current levels of Lactobacilli in your vaginal microbiome. There can be too much of a good thing and high levels of Lactobacillus can actually cause symptoms too. 

If on top of that, you’re having stomach issues and symptoms like constipation, gas, bloating, or indigestion, talk to your doctor. They may be able to provide testing recommendations so you can understand the microbial diversity and health of your gut. 

Can I test my gut microbiome at home?

Outside of testing you can get through your provider, companies like Viome provide comprehensive gut microbiome tests. 

Specifically, Viome’s Gut Intelligence Test uses RNA sequencing to assess if you're having trouble breaking down certain foods, if opportunistic microbes are causing problems, if your microbes are impacting your blood sugar response, and much more. 

With your Viome results, you’ll receive 20+ gut health scores along with personal recommendations that target the areas of your gut health that need specific nutrients to support and that may be the root cause of symptoms such as GI issues, occasional gas and bloating, irregular bowel movements, skin irritation, hormone imbalances, trouble sleeping, trouble losing weight, and other symptoms associated with poor gut health. 

(Since posting this article, we heard from many of our community that you’re interested in testing your gut microbiome, so we’ve recently partnered with Viome to offer you $100 off their Gut Intelligence Test — just use EVVY100 on Viome.com!)