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Vaginal Microbiome Basics

This article is part of a series! If you want a little more background information, check out the blog category Vaginal Health for the earlier articles on female anatomy and microbes.

In a nutshell, there are microbes everywhere, and they do amazing and complicated things. We hear a lot about the gut microbiome, but there are individual "communities" of microbes living on many different parts of our bodies. Each community is unique and specialised, and we would be in serious trouble without them.

One especially interesting community of microbes is the vaginal microbiome.

Why the Vaginal Microbiome Matters

A healthy vaginal microbiome can protect us by reducing the risk of

  • Thrush (yeast infection)

  • Bacterial Vaginosis

  • Urinary Tract Infections

  • Pelvic Inflammatory Disease

  • Viral infections such as HIV and HPV

To look at it from a more negative angle, here are some of the conditions that have been found associated with the unhealthy microbiome condition called Bacterial Vaginosis:

  • Increased risk of pre-term birth

  • Increased risk of maternal and neonatal infections

  • Reduced success rate with IVF attemps

  • Increased risk of cervical cancer via poorer defence against HPV infection

  • Increased risk of CIN (growth of abnormal cells on the cervix)

  • Increased progression of cervical cancer

  • Increased risk of vaginal symptoms at menopause including dryness, atrophy and pain during intercourse

I don't want to scaremonger, and this is not about selling you a magic treatment. This is about making it clear that this information is important, and we shouldn't ignore any problems we might have in or around the vagina.

This series of articles will go on to discuss common problems, prevention and treatment (including self-management and home remedies) in more detail. For today, I'd like to introduce the spectacular and amazing microbial community that is the Vaginal Microbiome.

There's Not a Bear in There

(I do hope everyone remembers Playschool lol)

What we need for a healthy vaginal microbiome is dominance by a few very specific bacteria. Unlike the gut, diversity is not the aim for the vaginal microbiome.

We want Lactobacilli, and not just any Lactobacilli.

Many yoghurt-fans are familiar with that species name, thanks to the Lactobacillus Acidophilus offered by many natural yoghurts.

These are not the Lactobacilli that dominate the healthy human vagina.

There are more than 180 species of Lactobacilli identified so far. And within those species, there are also multiple strains. The technology now available for RNA sequencing of genetic material has made it possible to identify bacteria by species and strain, and it turns out that not just any Lactobacilli will work to protect the vagina.

The most effective bacteria on the job is Lactobacillus Crispatus.  

Lactobacillus Gasseri and Lactobacillus Jensenii are also strong defenders of our health.

The least helpful in the vaginal family is Lactobacillus Iners – it's still a friend, but it won’t protect you as well as its superstar cousins.

A person can have any or all of these microbes present, but the amount of each can vary.

These microbes are helpful to us because they produce bacteriocins and acids. Bacteriocins are weapons in the fight against rival bacteria - that is, the fight against infection. Acids are even more interesting because we can boost their effects to help manage common conditions of the vagina.

The Acid Story

First, let me issue a warning: there are ways to use acid for treatment but DO NOT apply pantry bleach, undiluted vinegar or other acids to your genitals. NEVER, EVER. The ways acid can be used for treatment will be explained further in another article in this series. Please get informed before you take action. Directly applying acids can and will cause damage and harm.

Acids produced by bacteria serve two purposes. Firstly, an acidic environment encourages growth of more lactobacilli - they don’t make it just for our benefit! Even more importantly, these acids can kill the cells of pathogens like HIV and the Herpes Simplex Virus. (Yes, really.)

Before I got involved with the vaginal microbiome, my thoughts about acids could have been summed up as: “Acid eats things. If it’s more acidic, it will eat more things or eat them faster.”

I certainly didn’t stop to wonder whether certain acids could punch holes in the cell walls of pathogenic bacteria.

Now we know they do.

Acidity is measured on a pH scale. Distilled water has a neutral pH of 7. The numbers above 7 indicate how alkaline a substance is, and the numbers below 7 indicate increasing acidity.

The pH of the human vagina should sit between 3.5 and 4.5 during the reproductive years.

Other mammals can have a healthy vaginal pH as high as 7.8. Humans are naturally more acidic because of our resident Lactobacilli, who in turn live on the glycogen buffet we provide for them.

Not all Acids are Equal

When it comes to doing battle with invading bacteria or viruses, not all acids are equal. Lactic Acid is more effective than other bacterial acids. And not only does the type of acid make a difference, but even within the group called ‘Lactic Acid’, there are multiple types that have varying effects.

This is one important reason why not all species of Lactobacilli are equally beneficial.

Different Lactobacilli strains produce different types of lactic acid, and some are more effective than others. The right Lactic Acid in the vagina, as mentioned, can kill unwanted micro-organisms and therefore help to stop an infection before it starts.

Other acids are also produced inside the vagina

The same bacteria can also produce hydrogen peroxide (an acid commonly referred to as bleach), but they require some oxygen to do it. Oxygen is only present in the vagina when we introduce it with activities like inserting a tampon, or having intercourse.

Other bacteria in the vagina also produce acetic acid (as found in vinegar).

These acids are not as effective in defending the vagina against sexually transmitted infections, and they are not as helpful in maintaining a healthy balance in the microbiome. However, they do have a role and can be used in treatment formulas because lactic acid does its job more effectively when it’s working in an already acidic environment.

Just a reminder: DO NOT apply pantry bleach, undiluted vinegar or other acids to your genitals. The specific ways acid can be used for treatment will be explained in another article in this series. Misusing acids can and will cause damage and harm. (This is not a sales pitch, all the articles will be available on the blog.)

The Benefit to Our Health

By dominating the environment with their lactic acid, our Lactobacilli create a self-sustaining healthy environment that promotes more Lactobacilli and limits other potentially harmful micro-organisms.

Some pathogens are killed before they can multiply and cause a disease state. This is the fate we want for viruses like HIV and HPV.

Many other microbes are kept in check. These are microbes that are so common we expect to always have a small population of them, or we're exposed to them regularly in our daily lives.

A well-known example of this is the fungal organism Candida Albicans.  An overgrowth of C. Albicans (or possibly other Candida species) results in the condition many know as Thrush. Some countries prefer the term Candidiasis. Either way it’s unpleasant, uncomfortable, and tends to keep coming back if we don’t have a healthy microbiome. (There will be an article on Thrush.)

Some other potentially harmful microbes that are kept in check are Gardnerella Vaginalis, Atopobium Vaginae, Streptococcus, Staphylococcus, E. coli, Shigella and Proteus. You may recognise some of those, or have taken antibiotics to defeat them. We can’t avoid these bacteria – they already live on or in us and on many things we come into contact with. They are very likely to be present in the vagina, or be introduced occasionally, and we need Lactobacilli to keep them under control.

Research into the vaginal microbiome continues, and we will probably keep finding out new and interesting information on our resident microbes.

The underlying situation seems clear: the vaginal microbiome influences not only our comfort but also our sexual, reproductive and general health.

Fortunately, there is also evidence that there are multiple options for altering and improving the microbiome for the benefit of our health. And I will get these options loaded up onto the blog as soon as I can!

Check out the rest of the blog HERE - articles in this microbiome series can be found under the category Vaginal Health.

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Information provided on this site is intended to be educational. It isn’t intended to provide medical advice and does not replace advice from your health practitioner.