Vaginal flora refers to the microecosystem of different species of bacteria that are present in the vagina. These bacteria help maintain the ideal environment to keep the vagina healthy and avoid infections. Sustaining an ideal pH and promoting Lactobacilli — a type of good bacteria — are essential in gynecological health.

This article discusses the delicate balance of bacteria in the vagina, its importance to a person’s health, and what someone can do to maintain or restore it.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms, “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Vaginal flora refers to the different species of bacteria that live in the vaginal tract.

According to a 2016 article, although scientists have identified over 250 bacterial species, a healthy vaginal microbiome consists mostly of Lactobacillus.

Lactobacilli help to maintain the vagina’s healthy pH.

In addition, these bacteria also produce lactic acid, which can help prevent less beneficial species from growing and colonizing the vagina.

A newborn starts to colonize bacteria from the birth parent’s vagina if they have a vaginal birth. Afterward, breastmilk provides more bacterial species to the infant.

During the reproductive phases of a female’s life, hormones promote the growth of over 120 species of Lactobacilli in the vagina.

In females who have not started menstruating and those who are postmenopausal, a lack of estrogen means the vaginal flora mainly consists of skin and gut flora. However, the Lactobacilli can be present in the vagina.

Vaginal flora and pH can vary based on a person’s race and genetics.

A 2021 review article suggests that the differences in vaginal microbiomes could occur due to:

  • genetic factors, such as the immune system
  • receptors on the epithelial cell surfaces
  • the quantity and components of vaginal discharge

More research is required to understand the differences in vaginal microbiomes.

The 2016 article notes that obstetrician and gynecologist Albert Döderlein was the first to explain the importance of bacteria in the vagina. In 1892, he described the vaginal bacillus as a long, gram-positive bacillus occurring in vaginal secretions.

Döderlein and his colleagues explained how vaginal bacteria produce lactic acid, which inhibits other pathogenic species, thereby maintaining the health of the vagina.

Since then, the article states that more scientists have proposed different ways to classify the different types of flora:

  • 1914: Manu af Heurlin characterized the vaginal flora between those who were pregnant and not pregnant and between children and adults. He also attempted a grading system that ranged from healthy flora to disturbed flora.
  • 1921: Robert Shröder distinguished between three different vaginal flora types. Gynecologists still use these types when determining between normal flora, bacterial vaginosis (BV), and other types of flora.
  • 1930: Ludwig Nürnberger agreed with Döderlein that there were only two types of vaginal flora — normal and abnormal.
  • 1948: Otto Jirovec presented six classifications of vaginal flora:
    • normal
    • abnormal
    • abnormal with leucocytes — white blood cells
    • gonorrhea
    • trichomoniasis
    • candidosis
  • 1955: Herman Gardner and Charles Dukes noted the importance of the microscopy vaginal fluids. They defined a diagnostic criteria called clue cells. They thought that BV was a sexually transmitted infection (STI).
  • 1984: Per-Anders Marfh realized that BV was “a replacement of lactobacilli by characteristic groups of bacteria, accompanied by changed properties of the vaginal fluid.”

Using technological advances such as genomic sequencing, scientists now understand the different species of bacteria that live in the vagina.

The delicate balance of bacterial diversity can determine the health of someone’s vagina.

Research suggests that unbalanced microbiota can lead to vulvovaginal infections, such as BV and vulvovaginal candidiasis.

According to a 2018 review, there is an association between BV and an increased risk of STIs and other infections, such as pelvic inflammatory disease. Additionally, for someone who is pregnant, BV can cause preterm labor or birth.

Furthermore, the review suggests a link between diminished Lactobacillus dominance and the failure of in vitro fertilization (IVF) and pregnancy loss.

As well as bacteria, the vaginal flora includes yeasts.

In a healthy vagina, the Candida species exists as a yeast form. If this type of fungus multiplies, it can cause vulvovaginal candidiasis. People may refer to this as a vaginal yeast infection, and symptoms can include vaginal itching, pain, and atypical vaginal discharge.

Ensuring a healthy bacterial diversity in the vagina is key to its health, and there are several factors to consider to prevent dysbiosis, or unbalanced flora.

Diet and nutrition

One important factor to consider is diet and nutrition. For example, a 2020 review suggests that Candida, the yeast that causes common vaginal infections, is highly flexible to shifts in diet.

Another 2020 review explains that the gut and the vagina communicate via crosstalk and that bacterial strains can transfer from the gut to the vagina, stimulating the immune system.

For this reason, supporting flora in both the gut and vagina is beneficial to vaginal health.

For example, a 2020 review indicates that consuming probiotic Lactobacillus can help restore and maintain vaginal flora. However, the data is mixed regarding how much difference probiotics can make on vaginal flora, and more research is required.

According to a different 2020 review, diets rich in nutrients, such as vitamins and minerals, are associated with vaginal wellness, including a reduction in BV and human papillomavirus (HPV).

Conversely, diets deficient in these nutrients and too much fat and sugar have negative consequences on vaginal health.

Learn more about whether diet can improve a person’s vaginal health.

Stress

A 2018 review suggests that stress can have adverse effects on vaginal health.

The review explains that stress hormones, such as cortisol, decrease the abundance of beneficial Lactobacilli, causing inflammation and worsening symptoms of vaginal infection.

A person can consider the following to help reduce stress:

Learn more about how to treat and manage stress.

Smoking

Research suggests that smoking has a detrimental effect on vaginal flora. When scientists compare those who smoke to those who do not, they have found that tobacco seems to diminish lactobacillus and increase pathogenic bacteria.

A person who smokes may wish to quit to help maintain their vaginal flora.

Learn more about how to quit smoking.

Sexual activity

Sexual intercourse or other sexual activity can introduce bacteria that can interrupt the balance of vaginal flora, leading to BV. One reason this may occur is that semen is alkaline, which can disrupt the pH of the vagina.

A person may be more likely to develop BV if they have sex with a new partner or have multiple sexual partners.

Sexual activity can also trigger vulvovaginal candidiasis.

It is important to note that BV and vulvovaginal candidiasis are not STIs.

To help prevent disrupting the vaginal flora during sexual activity, a person may wish to use barrier methods of protection, such as condoms or dental dams.

Medical treatment is available to restore the balance of vaginal flora. Antibiotics can treat BV and a person can use over-the-counter medications, such as pessaries, to treat vulvovaginal candidiasis.

Learn more about yeast infections after sex.

Douching

Douching is washing or cleaning out the vagina with water or other fluids.

The Office on Women’s Health (OWH) advises people do not douche as it can change the balance of flora and natural acidity in the vagina.

OWH explains there is a link with douching and some health problems, including BV, vaginal irritation, and pelvic inflammatory disease.

The vagina is self-cleaning and does not require any cleaning products. However, some people may wish to clean the vulva using warm water and mild, unscented soap.

Learn more about cleaning the vagina here.

Flora, including Lactobacillus, protect the vagina from infections.

BV and vulvovaginal candidiasis are common conditions that have unbalanced flora as their root cause. Following a healthy diet, safe sexual practices, and avoiding stress and smoking are strategies a person can use to reduce the risk of developing these conditions.

Additionally, it is essential that people do not perform vaginal douching as this upsets the balance of healthy bacteria.