Your vaginal microbiome is a complex ecosystem of many microorganisms, including bacteria and fungi. Of all the microbes that live inside the vagina, lactobacilli bacteria are the local heroes because they help maintain the health and stability of the vaginal microbiome

One particular species, Lactobacillus crispatus, seems to get the most attention: it’s like the Kim Kardashian of protective bacteria. However, there are several other species in the Lactobacillus family that deserve our attention and appreciation (shoutout to Kourtney, Khloe, Kylie, and Kendall).

In this article, we’ll be discussing Lactobacillus gasseri, an equally hard working cousin of L. crispatus. Let’s dive in!

How does L. gasseri protect the vaginal microbiome?

The products that L. gasseri releases help protect the vaginal microbiome in two key ways: they stabilize vaginal pH, and they kill various harmful microbes.

A stable vaginal environment

To function at its best, the vagina needs to maintain stable, acidic pH levels. When pH levels rise above or drop below healthy pH levels, lactobacilli species struggle to flourish, and pathogenic bacteria can grow and thrive. To prevent this, L. gasseri cells secrete lactic acid and hydrogen peroxide, both of which help maintain an ideal vaginal pH.

Of all the lactobacilli species that populate the vagina, L. gasseri is the second highest producer of lactic acid; only L. crispatus produces more.

Microbial communities dominated by L. gasseri also tend to be highly stable over time.

Some researchers have hypothesized that instability in the vaginal microbiome could increase one’s susceptibility to infections. However, other studies have shown that the vaginal microbiome can shift and change substantially over time, even in people who don’t experience frequent infections or vaginal symptoms: for example, menstrual cycles and sexual activity can cause temporary instability in the microbiome. Although we still don’t fully understand the importance of stability–or lack thereof–in the vaginal microbiome, ongoing research will help get us there, and Evvy will keep pushing for more discovery!

On the offensive: the antimicrobial activities of L. gasseri

The evolutionary principle “survival of the fittest” applies to all living species, including bacteria. Bacteria fight each other for environmental resources like nutrients and living space; if there are too many bacteria in one area, none of them will thrive. 

In their bid to survive these battles, bacteria can secrete antibiotic molecules that suppress or even kill other bacterial species in their environment. This process helps our bodies maintain a balanced, healthy microbiome.

Let’s consider some key compounds that L. gasseri secretes to maintain its place in the vaginal microbiome:

Lectins and Bacteriocins

These two molecules act as the body’s natural antibiotics. They can slow or completely stop the growth of other bacteria: this is called bacteriostatic activity. In some cases, they kill other bacteria outright through bacteriocidal activity.


A surfactant is a chemical compound that can surround and isolate neighboring molecules from one another: soaps and detergents are common household 

surfactants. Many bacteria make natural surfactants (aka biosurfactants) that can help fight invaders. These biosurfactants prevent pathogenic bacteria from attaching to the inner walls of the vagina

Biosurfactants also prevent these bad bacteria from forming biofilms. Without their protective biofilms, pathogenic bacteria are more susceptible to antibiotic medications. L. gasseri releases biosurfactants that can prevent the following pathogens from building biofilms inside the vagina:

  • Candida albicans (the primary culprit in yeast infections)
  • Escherichia coli (associated with urinary tract infections)
  • Neisseria gonorrhoeae (associated with the sexually transmitted infection [STI] gonorrhea)

How L. gasseri plays defense for your vaginal environment

In addition to the aforementioned proactive molecules, L. gasseri secretes other products that defend the vaginal environment against invaders. 

Extracellular Vesicles (EVs)

When viewed under a microscope, EVs look a bit like bubbles ballooning off the side of the cells that create them. These “bubbles” consist of a double-layered membrane of lipids (fats) that encloses and carries various molecules from inside a cell to the environment around it. Once released from its parent cell, an EV can fuse with another cell to deliver its contents.

EVs released from L. gasseri prevent pathogens from attaching to cells of the vaginal lining. In the presence of these EVs, bacteria like E. coli and E. faecalis struggle to colonize the vagina. EVs from L. gasseri also have a positive impact on other Lactobacillus species: the vesicles can help other lactobacilli attach more firmly to the vaginal lining, thereby promoting the stability of Lactobacillus communities in the vaginal microbiome.

Extracellular Polymeric Substance (EPS)

Bacteria use carbohydrate- and protein-rich EPS to build their biofilms and stabilize their communities. At the same time, EPS secreted by lactobacilli prevents bad bacterial and yeast species from forming biofilms of their own

EPS is even effective against mixed biofilms: these stubborn biofilms contain multiple types of pathogenic bacteria, and they are implicated in bacterial vaginosis (BV), antibiotic resistance, and BV recurrence.

Lactobacilli can also secrete EPS into the surrounding environment to protect themselves against external stresses and reduce inflammation in the vagina. Clearly, EPS is a powerful tool in the fight against vaginal infections.

How else does L. gasseri  benefit the vaginal microbiome?

This humble bacteria protects the vagina against a whole host of potential infections. In addition to the stability it provides and the helpful products it secretes, L. gasseri has been connected to a number of other positive outcomes:

While it’s often overshadowed by L. crispatus, L. gasseri clearly occupies an important position in the vaginal microbiome.

From the pathogen-fighting products it releases to the community stability it creates, this Lactobacillus is worth our attention. Let’s discuss the ways you can support L. gasseri to optimize vaginal health.

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

What can I do to support L. gasseri in my vaginal microbiome?

Your day-to-day habits can impact your vaginal microbiome, both positively and negatively. The intimate hygiene and sexual health products you do or don’t use can affect the organisms in your microbiome, including L. gasseri

Personal Lubricants: Read the Labels

Personal lubricants can help combat vaginal dryness and improve comfort during gynecologic exams and sexual activity. However, the chemical makeup of some lubricants may have a detrimental effect on protective bacteria like L. gasseri. Chlorohexidine gluconate and nonoxynol-9, which are common ingredients in commercial lubricants like K-Y Jelly, can significantly inhibit the growth of protective lactobacilli species. If your lubricant of choice includes one or both of these chemicals, consider switching to a lube without them.

Fortunately, other personal lubricants like Astroglide® Liquid lube and Good Clean Love® Almost Naked® lube do not inhibit Lactobacillus growth. However, the Almost Naked® lube can decrease the ability of lactobacilli to attach and stick to the vaginal lining, which may inhibit their ability to protect the microbiome.

Different bodies may react differently to the same lubricant, so it’s important to read the ingredients of each lube you try: this can help you determine the types that work best for you. Evvy's advisor, Dr. Jill Krapf, M.D. has some helpful recommendations in this guide

Vaginal Douching: Just Don’t Do It!

Elsewhere on the blog, we’ve discussed the dangers of douching and feminine hygiene products. Commercially available douching products can disrupt and inflame the vaginal lining; this can reduce the protective effects of lactobacilli and allow pathogens to flourish, leading to infection.

Even “natural” douching products based on ingredients like vinegar, baking soda, and iodine can be problematic. While these types of douches can inhibit the growth of pathogenic E. coli, they also slow the growth of protective lactobacilli, including L. gasseri. They also slightly increase the rate of cell death in the vaginal lining, further disrupting the microenvironment.

Long story short: don’t douche! Your vagina is self-cleaning and well-equipped to flush away bad bacteria through discharge. If you’re worried about a change in your normal discharge, consult a healthcare provider to determine the best course of action.

My Evvy test tells me I have L. gasseri in my microbiome, but I still have vaginal symptoms…why?

We’ve just spent all this time discussing the benefits of an L. gasseri presence in the vaginal microbiome, so it’s easy to assume that plenty of L. gasseri = a happy vagina. Unfortunately, not all L. gasseri are created equal.

In the wise words of microbiome researchers Atassi and colleagues, “The presence of a particular species in the vaginal microbiota is not sufficient to determine its benefit to the host.” (In plain English: just having L. gasseri in your microbiome doesn’t guarantee that you’ll be symptom-free.)

Lactobacilli are like any other living organism: a lot of variation exists within individual species. When faced with the task of defending against and killing pathogenic invaders, some strains of L. gasseri are better than others. For example, some strains of L. gasseri are quite good at slowing the growth of C. albicans, a common pathogen that causes yeast infections, while other strains are less effective. Similarly, some strains are better than others at inhibiting UTI-associated bacteria

Additionally, recent research has reclassified the L. gasseri group into two distinct species, L. gasseri and L. paragasseri. While both species appear to be protective in the vaginal microbiome, they may have unique metabolic profiles: the two species metabolize the so-called building blocks of life (e.g., proteins, fats, carbs, etc.) in different ways. These different metabolic activities may help explain why the two species are effective against different pathogens.

These findings suggest that the mere presence of L. gasseri in your microbiome doesn’t guarantee you protection against all possible pathogens. As with many aspects of vaginal health, we need more research to better understand the specific effects of various bacterial strains in the vaginal microbiome. 

This is exactly why we use metagenomic sequencing in the Evvy Vaginal Health Test: it allows us to access data about each of the different microbial strains in the vaginal microbiome. These data will help us advance the research on all of these microbes and eventually share what we learn with our community.

Although there is still more research to do, Evvy is here to help right now. We’ll provide you with in-depth analyses of your unique microbiome and real-life strategies to address imbalances and promote optimal vaginal health. Eligible patients with vaginal symptoms that require care can also access Clinical Care with Evvy, the first-ever platform for vaginal healthcare that combines state-of-the-art testing, prescription treatment, and 1:1 coaching.

Referenced in this article: