Probiotics and IBS: Should you trust your gut?

IBS is a common disease that’s said to affect between one and two in 10 people in the UK. Its’ effects on people’s every day lives can be frustrating, painful and inconvenient.

Probiotics are an easy-to-access supplement reported to ease these problems. But how effective are they? Leading gastroenterologist Dr Aathavan Loganayagam asks, ‘While many view them as natural and safe therapeutic agents, how effective are probiotics in reducing IBS symptoms?’

What are probotics?

Probiotics are defined as ‘live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.’. There are hundreds of probiotic varieties that are available, ranging from capsules, powders and liquids alongside those that are additives in food, such as yoghurts, fermented milk drinks and fermented products.

Why could probiotics be useful in IBS management?

There are several reasons:

• Biological cause

It’s been found from animal and human studies how gut microbiota may play a role in the pathogenesis (biological cause) of IBS. There were differences observed between the microbiota of people with and without IBS. It could be the case that while these differences might be a consequence of the condition, studies have shown that transplanting the faeces of mice with IBS to healthy mice leads to changes microbiota and the onset of IBS-like symptoms.

• Influence on symptoms

The gut microbiota may influence IBS symptoms, with lower numbers of bifidobacteria associated with higher pain scores in IBS.

• Negating the effect of a low FODMAP diet

Researchers at Kings College London found that changes in the microbiota seen on a low FODMAP diet could be offset by probiotic supplementation in a recent study. 

How might probiotics work for IBS?

As mentioned above, we consider there is an imbalance of microbiota in a proportion of people with IBS. Missing strains of beneficial bacteria may be replaced, or compete with, excluding unfavourable strains.

Probiotics may also work by:

• Altering gut fermentation patterns
• Transforming motility (movement of the gut and contents within it) of the gut
• Improvement of the epithelial barrier function of the gut (preventing harmful organisms/substances from entering the body)
• Reduction of visceral hypersensitivity (sensitivity to intestinal pain)
• Changing anxiety behaviours and brain activity in IBS via the gut-brain axis.

How effective are probiotics in IBS?

There has been a large amount of research into the effectiveness of probiotic supplements for IBS. Many of these studies have shown that probiotic supplements are both safe and useful in some individuals, firm and specific recommendations in practice about which dose or strain to recommend in practice still can’t be made.

In part, this is due to the considerable variations (heterogeneity) between studies in terms of:

• Dose, strain and form (capsule/powder/tablet/drink) of probiotic used
• Probiotic treatment time length (typically ranging from four to 16 weeks)
• How compliant participants were in taking the probiotic
• Baseline symptoms and IBS sub-type
• Participants’ diets
• Measured outcomes (for example; improvement in IBS symptoms, bowel habits, quality of life etc)
• Variability in baseline microbiota between individuals

What recommendations are there about the use of probiotics for IBS?

There is currently insufficient high-quality evidence to make recommendations about the use of probiotics to treat IBS, based on a conclusion in guidelines published by the American Gastroenterological Association (AGA) in 2020.

A guideline published by the British Society of Gastroenterology (BSG) in 2021 recommended differently, however. While it said there is not enough data to recommend any specific species or strain at this time, it was suggested that probiotics can be trialled as a first line therapy for IBS. It was advised that patients who want to try probiotics should take them for up to 12 weeks. If their symptoms don’t improve, they should discontinue use. 

What are the overall takeaways regarding effectiveness of probiotics for IBS?

• Probiotics appear to be safe for IBS, with few adverse events reported in most studies.
• A mild improvement in symptoms should be advised
• Benefits observed in one patient may not translate to another, as they may relate to specific symptoms
• Trial one product at a time for a minimum of four weeks, and monitor symptoms. Discontinue use if you notice no improvement after 12 weeks.
• It may take time – at least three to four weeks – to see benefits from taking a probiotic.
• Benefits from probiotics aren’t permanent and lost within days if you stop taking a probiotic, so you should take probiotics regularly.
• Ingredients in probiotic products need to be considered as they may be poorly tolerated. Synbiotics, which are mixtures of pre- and probiotics often contain FODMAPS, such as insulin or FOS.

Do you have persistent IBS symptoms that you’d like assistance with? Get expert advice from Dr Loganayagam by arranging an appointment with him via his Top Doctors profile.