Why Gut Health Matters in PCOS

If you are already dealing with PCOS and then you feel as if your digestion has become a second diagnosis, you are not imagining the link. Bloating, abdominal discomfort, constipation, diarrhoea, reflux and a sense that your gut is “reacting to everything” are common reasons our PCOS clients ask us for support. And research backs this up - a 2023 systematic review and meta-analysis found that women with PCOS had more than double the odds of IBS compared with controls.  

What is often missed in day-to-day healthcare is that gut symptoms are not just a quality-of-life issue. Digestive function impacts our hormone balance, can significantly affect inflammation, and it can mess with our metabolic health that influence how PCOS shows up in the body. This is the gut–hormone axis in action.

Remember: the gut is not just where food is processed. It is also where signalling molecules are made, where immune activity is regulated, and where hormone metabolism is influenced. That makes gut health especially relevant to PCOS, even if your main symptoms are acne, irregular cycles, unexplained weight gain, cravings or mood rather than gut symptoms.

Alongside this, a growing body of microbiome research suggests that women with PCOS often have measurable differences in gut microbial patterns compared with women without PCOS. A 2025 systematic review analysing human and animal studies reported that, across human studies assessing diversity, around two-thirds reported reduced gut microbial diversity in PCOS. What that means is we have far fewer types of bacteria in our guts – and this can have a knock-on effect on our health. A further study also supported consistent differences in gut microbiota patterns in PCOS across different population types, reinforcing that this is not limited to one country, diet pattern or body size. 

Microbiome research is still evolving, and it is not yet at the stage where we can run one stool test and “solve” PCOS. But the direction is clear enough to matter clinically: gut health is part of the hormonal picture.

How the Gut Communicates with Hormones

The gut communicates with the rest of the body through multiple overlapping pathways, and PCOS touches many of them at once. Three are particularly important in clinical practice: inflammation, insulin signalling, and gut-derived metabolites (that’s chemicals made by the bugs in our gut).

It is good to note that the gut is one of the largest surface areas open to the world (remember it’s open at both ends…), and that means our immune system has to keep watch over its comings and goings. This means around 70-80% of immune system resides in our gut, acting a bit like border patrol. When the intestinal barrier is under strain, or when microbial balance shifts (often referred to as dysbiosis), inflammatory signalling can increase. Low-grade inflammation is a recognised feature in many women with PCOS, and it can increase patterns of insulin resistance and ovarian androgen production. The clinical pattern is familiar: worsening bloating and bowel changes alongside flares in fatigue, cravings, skin breakouts, or cycle disruption.

Second, the gut plays a direct role in metabolic regulation. This matters because insulin resistance is common in PCOS, even in women who are not in larger bodies. The microbiome influences glucose regulation through its effects on energy harvest, gut permeability, inflammatory tone and signalling molecules. Recent research looks at the intersection between hyperandrogenism (high levels of ‘male’ hormones), metabolic dysfunction (blood sugar imbalances), and gut dysbiosis, including evidence from both human and animal models. 

Finally, our gut microbes are little biochemical factories. When we eat dietary fibre, our gut bacteria ferment them into special chemicals called short-chain fatty acids (SCFAs), including acetate, propionate and butyrate. These compounds feed the gut lining. And they also act as signalling molecules, influencing how sensitive we are to insulin, regulating our appetite, helping with gut motility (constipation anyone?), and organising immune function. SCFAs have been repeatedly highlighted in recent PCOS literature as one of the plausible links between diet, microbes and metabolic-hormonal outcomes. 

This is one reason fibre recommendations can feel confusing in PCOS. Fibre is not simply about having “regular bowels”. The type, dose and tolerance matter, and for some women with IBS symptoms, a sudden fibre increase can actually worsen bloating to begin with. A more sensible approach is to build slowly and strategically rather than aiming for perfection overnight.

The Microbiome, Oestrogen and Androgens

Hormones are not only made and used. They are also processed, transformed and cleared. The gut microbiome plays an active role in this, particularly through enzymes that affect ‘enterohepatic recycling’, where the body clears or doesn’t clear used chemicals, like hormones.

A key concept here is the oestrobolome, which refers to the bugs in our gut which are involved in oestrogen metabolism. Ideally our body cleverly packages oestrogen (and other hormones) into bile for excretion via our stool. If our gut has a lot of microbes that produce an enzyme called betaglucuronidase, that can then un-package those hormones, influencing whether they are excreted or reabsorbed. This can mean that the gut bacteria are causing us to have more active hormones in circulation than we want – adding to our hormone imbalance and symptoms. 

PCOS is not classically defined by “high oestrogen” in the way some people online suggest. However, oestrogen metabolism still matters because hormonal systems are interlinked. The ovaries, liver, gut and adipose tissue are in constant conversation. When gut function is compromised, it can add friction into that system, particularly around inflammatory signalling and metabolic control.

Androgens are central in PCOS, and the relationship between androgens and the microbiome appears to be bidirectional. Research shows that hyperandrogenism (or high levels of ‘male’ hormones) is associated with gut microbial changes, and animal studies suggest that transferring microbiota from female mice with PCOS can induce PCOS-like features, highlighting a potential role rather than a simple association. 

Signs Gut Health May Be Affecting Your PCOS

Not every woman with PCOS has gut symptoms. Equally, you can have significant gut-driven effects without textbook IBS. In practice, we pay attention to gut involvement when a woman with PCOS describes patterns like persistent bloating, pain after meals, unpredictable bowel habits, increased food reactivity, or a sense that symptoms flare with stress.

It can also show up more subtly, such as energy dips and intense carbohydrate cravings after meals, skin flares alongside digestive upset, or difficulty progressing with PCOS goals despite doing “all the right things”. These patterns do not prove that the microbiome is the root cause, but they are often a sign that the digestive system deserves a proper, personalised look rather than another generic PCOS meal plan.

For many women, the confusion comes from conflicting gut advice online. One week it is “eat more fibre”, the next it is “avoid fibre because it feeds SIBO”, then it is “take probiotics”, followed by “probiotics make it worse”. The reality is that gut support is rarely one-size-fits-all. IBS symptoms can overlap with PCOS, but they can also reflect dysbiosis, stress-related gut-brain axis activation, bile acid issues, medication effects, poor meal timing, inadequate chewing and rushed eating, or simply increasing fibre too quickly.

Hydration is a good example of a basic factor that is often overlooked. Adequate fluid intake supports bowel motility and stool consistency, and it also helps fibre do its job properly. In PCOS, hydration tends to be discussed mainly in the context of weight, but clinically it matters for digestion, appetite signalling and maintaining steady energy through the day.

If you are struggling with bloating and bowel changes alongside PCOS symptoms, it can be reassuring to know there is a physiological explanation. The goal is not to “fix your gut” with a supplement trend. The goal is to support gut function in a way that improves how your body handles inflammation, blood sugar regulation and hormone metabolism.

If you would like to explore this topic further, you can read more about how gut health can influence PCOS symptoms in our previous article on gut health and PCOS.

If you are looking for personalised guidance, you can also learn more about nutritional therapy support for PCOS through our clinic services – just click here.

This article is for educational purposes only and does not diagnose or treat medical conditions. As a nutritional therapy clinic, we do not advise on medications. If you have persistent digestive symptoms, unexplained weight loss, blood in stools, severe pain, or symptoms that are worsening, please speak to your GP to rule out underlying medical causes.