Could SIBO Be the Missing Link in Your PCOS Symptoms?

If you’re living with PCOS and constantly battling bloating, constipation, sugar cravings, or stubborn weight, even when you’re “doing everything right” – you’re not imagining it.

These symptoms are common, but that doesn’t mean they’re normal. For some women, a hidden gut imbalance called SIBO (Small Intestinal Bacterial Overgrowth) could be quietly fuelling hormone disruption behind the scenes.

Let’s explore how SIBO could be affecting your PCOS symptoms and what steps you can take to support your gut health.

What Is SIBO and Why Does It Matter in PCOS?

SIBO occurs when bacteria that normally live in the large intestine start to overgrow in the small intestine, where they’re not meant to be. This interferes with digestion, nutrient absorption, and the natural rhythm of the gut.

For women with PCOS, this can be a significant problem. The gut isn’t just about digestion, it plays a key role in hormone balance, inflammation, blood sugar regulation and mood. When gut health is compromised, PCOS symptoms often become harder to manage.

How SIBO Affects Hormones, Weight, and Cravings

Here’s how SIBO may be making your PCOS symptoms worse:

• Bloating and IBS-like symptoms: Excess bacteria ferment carbohydrates too early in digestion, creating gas and discomfort – especially after meals.

• Sugar cravings and energy crashes: Poor absorption and inflammation can impair blood sugar control.

• Oestrogen dominance and poor detoxification: The estrobolome (the part of your microbiome that helps break down oestrogen) becomes disrupted, which can lead to heavier periods, breast tenderness or PMS-type symptoms.

• Nutrient deficiencies: SIBO interferes with absorption of key nutrients like iron, B12, and zinc, all essential for hormone production and ovulation.

• Stubborn weight gain: Ongoing inflammation and disrupted insulin signalling can make it harder to shift weight, even on a healthy diet.

Common SIBO Symptoms (Especially in PCOS)

• Bloating that worsens as the day goes on

• Constipation or loose stools (or alternating between both)

• Feeling full quickly, nausea or indigestion

• Brain fog, fatigue or low mood

• Strong cravings for sugar or carbs

• Acne, especially around the chin and jawline

• Low iron or B12 on blood tests without clear explanation

What Causes SIBO and Why Are Women with PCOS More at Risk?

There are several risk factors that overlap between SIBO and PCOS, including:

• Slow gut motility: Common in women with thyroid imbalances or high stress (both of which are frequently seen alongside PCOS).

• Chronic constipation: Increases the likelihood of bacteria stagnating and overgrowing.

• Frequent antibiotic use: Can disrupt gut flora balance and lead to overgrowth.

• Blood sugar imbalance: High insulin can affect the gut barrier and microbiome.

SIBO may also be more common if you’ve been diagnosed with IBS or have a history of food intolerances, coeliac disease or endometriosis.

How Do You Test for SIBO?

SIBO cannot be detected on a stool test. The most common functional test is a SIBO breath test. This measures hydrogen and methane gases produced by bacterial fermentation in the small intestine.

Testing is particularly helpful if you’ve tried fibre, probiotics or FODMAP changes and your symptoms haven’t improved.

As part of my 1:1 nutrition programmes, breath testing can be arranged to investigate persistent gut symptoms in a targeted way, if appropriate.

How to Support Gut Health with PCOS and SIBO

You don’t need to follow a restrictive diet forever, but short-term, gentle gut support strategies can make a big difference. These include:

1. Focus on Blood Sugar Balance

• Base each meal on protein, non-starchy veg, and healthy fats

• Reduce snacking to support the migrating motor complex (MMC) – the gut’s natural cleansing wave that clears bacteria between meals

2. Consider a Low FODMAP or Modified Diet Temporarily

• Avoid over-restriction, but reducing fermentable fibres short-term can help ease bloating

• Work with a practitioner to ensure it’s not nutrient-depleting

3. Support Digestion

• Chew food thoroughly and eat slowly

• Herbal teas like ginger, fennel or peppermint can help with bloating

• Gentle bitters (e.g. lemon juice or apple cider vinegar before meals) may support stomach acid and bile flow

4. Use Targeted Supplements if Needed

• Digestive enzymes to support absorption

• Probiotics – specific strains may support gut integrity, but can worsen symptoms if used too early with active SIBO

• Antimicrobial herbs like oregano or berberine may be helpful but should be used under guidance

When to Get Support

If you’re experiencing ongoing gut issues alongside PCOS symptoms that don’t shift with diet changes, it may be time to look deeper.

You don’t need a SIBO diagnosis to start supporting your gut, but the right approach at the right time can make a huge difference to your hormone health, energy and long-term progress.

Next Steps

Not sure what’s driving your bloating, cravings or cycle symptoms?

Start by downloading my free Hormone Health Snapshot to get a clearer picture of what could be affecting your gut and hormones. If you’d like to explore functional testing or get personalised support, book a free 30-minute discovery call. I work online with women across Manchester, and the UK.

Professional Support You Can Trust

I’m a BANT-registered nutritionist and health coach with over a decade of experience helping women rebalance their hormones using a root cause, food-first approach. I offer online consultations and optional functional testing to investigate persistent gut or hormone imbalances.

Whether you’re diagnosed with PCOS or still searching for answers, I’m here to help you make sense of your symptoms and support your progress without overwhelm.

Updated in June 2025 to reflect new PCOS research and nutrition strategies.

Disclaimer

This blog is for general information and educational purposes only. It is not intended to provide medical advice, diagnose health conditions, or replace personalised care from a qualified healthcare professional.As a BANT-registered nutritionist, I offer nutrition and lifestyle support to help manage and improve health outcomes, but I do not diagnose or treat medical conditions. Always consult your GP or healthcare provider before making changes to your diet, lifestyle, or supplements, especially if you have a medical condition, take prescription medication, or are pregnant or breastfeeding.Individual needs can vary, and what works for one person may not be appropriate for another. All information is evidence-based to the best of my ability at the time of writing, but research and guidance can evolve. If you're looking for tailored support, please get in touch to book a 1:1 consultation.