Sign Up
Conception Apr 22, 2020
8 Minutes

Does the gut microbiome hold the key to PCOS?

Here at The Journey we are very focused on the emerging research around the gut (and vaginal) microbiome. Specifically how it can help us achieve our goals of happy health small people. Type in ‘gut’ to the search bar and you’ll see! The research is new and definitely still evolving. However, there appears to be more and more insight gained about how these collections of bacteria, viruses and fungi could play a role in disease and how providing a healthy foundation from the start is key. Recent research has been taking a look specifically at the gut microbiome’ s role in Polycystic Ovarian Syndrome (PCOS), something that is said to impact as many as 1/5 women and something that can significantly impact fertility. Here’s what you need to know: 

The link between PCOS and the gut microbiome: 

The first thing to note about PCOS is that as many as 50% of those who suffer with it do not know they have it. Click here for much more on that. This is partly due to symptoms being highly variable, but also because often we believe what we know is ‘normal’.

You can have very few symptoms: irregular periods for example to a lot ie. excessive hair, insulin resistance, weight gain, acne, thinning hair, anxiety, chronic inflammation, depression, anxiety and aggression. One of the most common elements however when it comes to fertility is issues with ovulation which incidentally is the number one cause of female infertility. In many cases trouble getting pregnant can be the thing that leads to a PCOS diagnosis.

Another very common condition associated with PCOS is some form metabolic syndrome. This can be mild insulin resistance, to obesity, to type two diabetes. This is where the gut microbiome comes in.

The National Institute of Health, American Endocrine Society and European Endocrine Society have all made the link (7,8): 

All three bodies have linked metabolic abnormalities (which often come hand in hand with PCOS – as many as 70% impacted) to disorders of the gut microbiome. Specifically the collection and variance of the bacteria, viruses and fungi that live in our guts.

PCOS is a complex disorder, we do not yet fully understand… 

The reality is that at this stage we do not have a single, easy answer as to what causes PCOS. At the moment it looks likely caused by a variety of factors from genetics, to hormonal imbalances to metabolic disorder (1). However, the gut microbiome and our growing knowledge and understanding of it may hold some clues about what contributes to it and how to treat it.

There appears to be a link between the Gut microbiome and our metabolisms: 

As our understanding grows and evolves, it seems clear that the gut is not just for digesting and absorbing our food and nutrients. It relates to our immunity (click here), fat storage, nervous system and even connects to our brains via the gut-brain axis.

In fact, when researchers looked into the gut microbiome of patients with Diabetes (a common metablolic disorder) they saw several things including lower numbers of key bacteria: Firmicutes/Clostridium vs non diabetics (5).  They also found that adding ‘good bacteria’: Bifidobacteria and Lactobacillus reduced obesity, cholesterol and weight gain. (1)

When the delicate balance of our gut microorganisms gets pushed off there is a growing recognition that this can lead to disease: 

‘Under normal circumstances, the bacteria in the gut microbiome maintain a delicate, dynamic balance to prevent the development of various diseases’. (1)

Emerging research suggests that this could contribute to metabolic disorder, hormonal imbalance and PCOS.

One study (3) took gut microbes from mice with PCOS symptoms and transferred into health mice. The result? The healthy mice became sick with insulin resistance, cysts on follicles, smaller corpus luteum, higher testosterone and LH. They also had fewer pups. All classic symptoms of PCOS.

Ok so mice are not humans, but, there is mounting evidence that it acts in various ways with links between dysbiosis (imbalance) in gut bacteria and high androgen levels (male hormones), chronic inflammation, increased gut permeability and on mood based on it’s role in the gut-brain axis. In fact, between 30-50 gastrointestinal hormones are known to be involved in the gut-brain interaction. (1)

The immune system, gut microbiome and PCOS:

One of the things we do know is that the gut is a haven for our immune system. Intestinal Lymphoid tissues contain 70-80% of the immune cells of the entire body and provide the anatomical basis for immune regulation.’ (1). We also know that many people with PCOS suffer from low level chronic inflammation. Click here for much more but essentially this is where our body’s immune response is constantly switched ‘on’ at low level which can cause damage to surrounding tissue.

Is the gut microbiome connected to the fact that many people with PCOS suffer from poor egg quality? 

Does this immune dysfunction contribute to poor egg quality that can be present with PCOS? Another study (4) demonstrated that people with PCOS related infertility have an imbalance in a particular ratio of immune cell: T Helper Cells. They showed that an imbalance of Th1/Th2 cells led to poor egg quality and ovulatory disorders. The key thing is that this was highly correlated to an imbalance in the gut microbiome.

So what causes the gut microbiome to be pushed out of optimum balance? 

First and foremost we know that the foundations for the gut microbiome start very early. Early seeds appear to be sown as early as pregnancy. The principal start however is during birth (via the birth canal), skin and breastmilk of the mother. Click here for much more and why a healthy microbiome if you’re a mum to be can be so powerful. 

Age, diet, stress and antibiotics all appear to play a role however in altering this balance. Zhang et al showed that diet can play a particularly important role (2). They showed that a high fat diet can relatively rapidly disrupt this delicate balance. Click here for more research that demonstrates that the gut microbiome can be shifted in as little as 24hrs. 

We know for now that a high fat, high sugar diet can exacerbate gut microbiome based disorders, however we also know that a health diet full of whole fruits, vegetables and fibre can have a very positive impact. Click here for more. 

Here is the good news: 

‘Studies have confirmed that the intake of foods with low GI can make ovulation and menstrual cycles more regular in patients with PCOS and normalised the metabolic index.’ (1)

The ‘diet’ (although we do not like this term) that continues to come out on top when it comes to fertility is the Mediterranean Diet. Research has shown that this approach which is based on whole grains, fruits and fats, principally plant-based sources of protein with meat and fish occasionally comes out on top. Click here for more. 

Exercise, the microbiome and PCOS: 

There is also mounting research around exercise and it’s impact on the microbiome. Specifically by increasing diversity (1). Resistance training has also shown a role reducing insulin resistance. Click here for much more. 


The trouble with store bought probiotic supplements (or any supplement) is  the highly variable dose and strains. Click here for more. 

However, what we are learning is that specific targeted strains can be a powerful positive. For example some studies have shown that Lactobacilli Reuteri and significantly improve insulin resistance, reduce fat accumulation and reduce inflammation. Another study looking at 60 patients who were given strains of Lactobacillus and Bifidobacteria saw drops in BMI, insulin levels, increased SHBG (click here as to why this is crucial for PCOS) and reduced chronic inflammation. (1)

Are prebiotics even better when it comes to the microbiome and PCOS?

Prebiotic/Probiotic? Can seem confusing. However, think of it this way. Probiotics add bacteria. Prebiotics feed the existing bacteria we have. Click here for more on these hidden heroes. 

Metformin is a drug that is prescribed to some diabetics but also to some women suffering with PCOS. One study however suggested that a form of prebiotic fibre: Inulin (from Chicory Roots) ‘improved the metabolic and inflammatory status of PCOS by regulating the gut microflora, similar to the action of Metformin.’ (1).

Ok so what is the bottom line to all of this? 

Once again there is a lot we do not know when it comes to the powerful role that the gut microbiome appears to play in our health. We still do not fully understand what causes PCOS to develop in a person. However, mounting evidence does suggest that having a healthy gut microbiome (diverse/no imbalances/full of the good guys: Lactobacillus and Bifidobacterium) can help our cause. The reality is a healthy diet full of whole foods, low sugar and processing, exercise plus speaking to our doctor about prebiotic/probiotic foods/supplements is likely only to have upside.

For more ways to tackle check out the links below. Hope is not lost!

PCOS and Exercise

Can Inositol help?

Science backed ways to improve egg quality:


1) Zhao X, Jiang Y, Feng X: Exploration of the Relationship between gut microbiota and Polycystic Ovarian Syndrome (PCOS): a Review: Geburtshlife und Frauenheikunde: 2020:80(2): 161-171

2) Zhang M, Yang X-J: Effects of a high fat diet on intestinal microbiota and gastrointestinal disease: World of Gastroenterology: 2016:22(40);8905-8909

3) Turnbaugh P J, Backhed F, Fulton L. Diet-induced obesity is linked to marked but reversible alterations in the mouse distal gut microbiome. Cell Host Microbe. 2008;3:213–223.

4) Lang Q, Xu W, Li X. Differential expression profile of immunological cytokines in local ovary in patients with polycystic ovarian syndrome: analysis by flow cytometry. Eur J Obstet Gynecol. 2016;197:136–141

5) He Q, Li X, Liu C. Dysbiosis of the fecal microbiota in the TNBS-induced Crohnʼs disease mouse model. Appl Microbiol Biotechnol. 2016;100:4485–4494

6) Qi X, Yun C, Sun L. Gut microbiota-bile acid-interleukin-22 axis orchestrates polycystic ovary syndrome [J] Nat Med. 2019;25:1225–1233.

7) Johnson T, Kaplan L, Ouyang P. Bethesda: National Institutes of Health; 2012. National Institutes of Health evidence-based Methodology Workshop on polycystic Ovary Syndrome (PCOS).

8) Legro R S, Arslanian S A, Ehrmann D A. Diagnosis and treatment of polycystic ovary syndrome: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2013;98:4565–4592.


This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.

The Journey Logo

Copyright © 2023

Welcome to The Journey

Each month we will be giving away a curated box of goodies to suit the individual stage of your Journey, worth £100. To enter the draw and join us, enter your details below. Winner announced at the end of the month.


Welcome to The Journey

Each month we will be giving away a curated box of goodies to suit the individual stage of your Journey, worth £100. To enter the draw and join us, enter your details below. Winner announced at the end of the month.


Next on your journey?