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

Okay, but why are we bringing up the gut if we’re a vaginal microbiome company?

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 my vagina? And if there is, wtf is it for goodness sake?! 

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! 

How does the gut Microbiome affect the vaginal microbiome?

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

There are three different ways the gut microbiome 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 overall inflammation in the body, including in the vagina  
  • Your gut microbiome can change the levels of hormones, like estrogen which can have an effect on 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 microbiome (i.e., Candida, E. coli, Prevotella) get into the vagina by way of the gut. In science-speak, this is known as a reservoir—a place where a stable community of potentially harmful bacteria hang out. Periodically those harmful microbes will colonize the vagina (and then maybe even the bladder) and cause symptoms. 

We also know that the levels of Lactobacillus in the gut correlated with levels of Lactobacillus in the vagina. So to put it simply, if your gut is healthy, then 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 of time

For our teeny-tiny bacteria, the GI tract is huge! And traveling through it to reach the vagina would be kind of like us trying to walk across the US 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 the gut. 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 are concerned about UTIs). 

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 an 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 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 = 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 BV or UTIs) will deplete bacteria in your gut as well as your vagina. And the loss of bacteria in your gut can in turn 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 LactobacillusSide 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 environment is less protective. 

Circling back to the gut-vagina connection, 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 through urination. 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 have the ability to add or remove these tags on estrogen molecules. Your gut microbiome are 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 and 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

How do I know if my gut is 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. 

Recurrent symptoms? Meet Evvy's at-home vaginal microbiome test, approved by leading OB-GYNs.
Learn more

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!)