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The Vaginal Biome

Updated: Jun 28, 2022

Bacterial vaginosis (BV) is the most common vaginal infection. Every year, one out of three women will get BV, with 84% having no symptoms. However, BV can be transmitted sexually, is hard to cure, and has been linked to more severe conditions, including other sexually transmitted infections (STIs), urinary tract infections (UTIs), childbirth complications, and infertility. It comes down to the vaginal biome.

To gain more insight, we recently sat down with two experts on the vaginal biome and women's health:

  • Melissa Herbst-Kralovetz, Ph.D., Associate Professor at the University of Arizona College of Medicine - Phoenix and the Director of the Women's Health Microbiome Initiative

  • Pita Navarro, Head of Clinical Research and Operations at Evvy

In this article, we'll uncover everything you need to know about what the vaginal biome is, why it's important, what changes it, and ways to make it healthy.

What is the Vaginal Biome?

Dr. Herbst-Kralovetz described the vaginal biome as "a community of bacteria that are working to keep us healthy in a woman's reproductive tract." Having a good, stable balance (homeostasis) of beneficial bacteria helps fight against infection.

The vagina consists of an inner lining (vaginal epithelium) of multiple layers of flat, skin-like cells (squamous cells). Mucous membranes in the vagina (vaginal mucosa) produce a protective layer of fluid, containing nutrients on which bacteria feed, such as glycogen. Although a healthy vagina has different types of bacteria, lactobacilli are the predominant ones.

Why Your Vaginal Biome is Important

When you think about the vagina, comparisons to the "good" bacteria and "bad" bacteria in the gut probably come to mind. However, as Dr. Herbst-Kralovetz put it, "the vaginal cavity has a unique ecosystem that's very different from the gut and other sites." According to Navarro, "you want to have one dominant species (of bacteria), and you want that species to be a lactobacillus species because that's known to produce, you know, lactic acid and help keep the vaginal pH low, and really protect from pathogens."

What Changes the Biome?

When lactobacilli in the vagina are depleted, other types of bacteria have a chance to take over. Many things can disrupt bacteria in the vagina.


The different stages of a woman's life can affect your vaginal biome.

  • Premenarchial Stage: Before a woman starts menstruating, they have non-lactobacillus dominant flora.

  • Puberty Stage: When a woman reaches reproductive age, estrogen increases, the lining thickens, and they start having periods.

  • Premenopause Stage: As a woman ages, more estrogen is produced, and the vaginal biome is in a lactobacillus-dominant state in healthy women.

  • Perimenopause and Menopause Stage: At these stages, estrogen decreases, and the lining changes again, causing good bacteria to plummet.


Certain sexual practices can increase the risk of infections.

  • Unprotected sex spreads bacteria from semen and BV in male carriers.

  • Sex with new or multiple partners transfers bacteria.

  • Women who have sex with other women are at a greater risk because BV is so common.

  • Vaginal intercourse after anal sex can spread fecal bacteria.

Feminine Products

Anything introduced into the vagina has the potential of throwing it out of balance.

  • Douches

  • Scented sprays

  • Lubricants

  • Oral contraceptives


Several habits and behaviors have been linked to BV, including:

  • Smoking

  • Stress

An overgrowth of "bad" bacteria is due to many causes. An unbalanced (dysbiotic) vaginal ecosystem can lead to many adverse conditions, so health maintenance is essential.

5 Ways to Make Your Vaginal Biome Healthy

Chances are you'll experience an unhealthy balance at some point. Unfortunately, antibiotics aren't effective against BV, but here's what you can do (or avoid) to maintain a healthy balance.

Tip 1: Avoid Putting Anything in Your Vagina

Dr. Herbst-Kralovetz pointed out "certain celebrities promote things that you don't want to do to your vagina." The vagina is frequently likened to a "self-cleaning oven," so you don't need to do things like steaming or douching.

Tip 2: Use Protection During Sex

According to Dr. Herbst-Kralovetz, "every type of sex can put you at risk for bacterial vaginosis." So, abstinence is the best way to stay safe. Otherwise, use condoms.

Tip 3: Lead a Healthy Lifestyle

Tobacco increases the risk of BV, so it pays to stop smoking. It's also essential to find ways to relieve stress that lowers your immune system and makes you more susceptible to infections.

Tip 4: Only Use Vaginal-Specific Probiotics

LACTIN-V, a product in clinical trials, has shown some success in treating BV. This probiotic is taken orally rather than vaginally inserted.

Tip 5: Consider Vaginal Estrogen

Perimenopausal and menopausal women with recurrent infections may want to speak with their health care provider about using vaginal estrogen to build up the vaginal epithelium, to provide a more welcoming environment for lactobacillus dominance.

How Evvy Provides Information for Women

Evvy is a diagnostic test designed for women to them "know what's up down there." Navarro described their product as "an at-home vaginal swab that women can take, and we do metagenomic sequencing."

The vaginal health test is designed for "women who want to know all everything about their bodies," says Navarro. Information is gathered to help women suffering from recurrent symptoms and women in menopause. The test results reveal:

  • What bacteria are present

  • What the results may mean for their health

  • What they can do about it

Data the company collects, with clients’ consent, opens up opportunities to understand how the vaginal biome contributes to many factors, from STIs to BV and pregnancy to reproductive outcomes. According to Navarro, this new understanding can be used to "establish risk predictors" and "improve the lives of women and their families."

Gaps in the Research

Much research has been done on the gut biome and its relative abundance of protective bacteria. In contrast, the vaginal biome is the exact opposite, but little research exists.

  • Vaginal Biome: Navarro indicated there's not enough research on the vaginal biome. It's understood that a lactobacilli-dominant ecosystem is healthy, but the optimal value of a healthy biome is unknown.

  • Women of Color: It's known that African American and Hispanic women have higher rates of BV. Yet, research is lacking for other underserved and understudied populations, including Latinas and Native Americans.

  • Vaginal Probiotics: Research on probiotics is highly lacking as well. Unfortunately, "one or two clinical studies carried out for like 40 women" and "there's so much marketing behind everything," says Navarro.

What Action Will You Take for a Healthy Vaginal Biome?

We hope you found value from the key points taken from these interviews with Dr. Melissa Herbst-Kralovetz and Evvy’s Pita Navarro. Their work is vital in helping address women's health issues related to the vaginal biome and associated infections. I encourage you to commit to one action you've learned about today to keep your biome healthy. What healthy step will you take?

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