People often view probiotics as natural and safe therapeutic agents, but how helpful are they in IBS?
Probiotics are defined as ‘live microorganisms that, when administered in adequate amounts, confer a health benefit on the host’. In Australia, there are 100s of varieties available that range in form, from capsules, powders, liquids, and those added to food products, such as yoghurts, fermented milk drinks and fermented foods.
Why might probiotics be useful in the management of IBS?
There are a number of reasons for this:
- Firstly, animal and human studies suggest that the gut microbiota may play a role in the pathogenesis (biological cause) of IBS, with differences observed between the microbiota of people with and without IBS. While these differences may simply be a consequence of the condition, studies in mice show that transplanting the faeces of mice with IBS to healthy mice leads to changes in microbiota and the onset of IBS-like symptoms.
- Secondly, the gut microbiota may influence symptoms in IBS, with lower numbers of bifidobacteria associated with higher pain scores in IBS.
- Finally, probiotic supplementation may help to offset changes in the microbiota seen on a low FODMAP diet. This was shown in a recent study by researchers at Kings College in London.
How might probiotics work in IBS?
As mentioned, we think that microbiota may be abnormal in a proportion of people with IBS. Probiotics may work by replacing missing strains of beneficial bacteria, or competing with, and excluding unfavorable strains.
Probiotics may also work by:
- Altering fermentation patterns in the gut
- Changing gut motility (movement of the gut and contents within it)
- Improving gut epithelial barrier function (preventing harmful organisms/substances from entering the body)
- Reducing visceral hypersensitivity (sensitivity to intestinal pain), and/or
- Changing anxiety behaviours and brain activity in IBS via the gut-brain axis.
How effective are probiotics in IBS?
A large amount of research has been done to investigate the efficacy of probiotic supplementation in IBS. While many of these studies have shown that probiotic supplementation is both safe and effective in some individuals with IBS, firm recommendations about which dose or strain to recommend in practice still cannot be made.
This is in part due to the considerable heterogeneity (variation) between studies in terms of:
- Dose, strain and form (capsule/powder/tablet/drink) of probiotic used
- Length of probiotic treatment time (typically ranging from 4-16 weeks)
- How compliant research participants were in taking the probiotic
- Symptoms at baseline and IBS sub-type (e.g. IBS-C, IBS-D, IBS-M)
- Background diet
- Outcomes measured (e.g. improvement in IBS symptoms, bowel habits, quality of life etc.)
- Variability in baseline microbiota between individuals
What recommendations can be made about the use of probiotics for IBS?
A guideline published by the American Gastroenterological Association in 2020 concluded that there is currently insufficient high-quality evidence to make recommendations about the use of probiotics to treat IBS.
However, a guideline published by the British Society of Gastroenterology in 2021 recommended otherwise. They suggest that probiotics can be trialled as a first line therapy for IBS, but that there is not enough data to recommend any specific species or strain at this time. They advise that patients who wish to try probiotics should take them for up to 12 weeks and should discontinue use if their symptoms do not improve.
So what are the take home messages?
- Firstly, probiotics appear to be safe in IBS, with few adverse events reported in most studies.
- Patients should be advised to expect a mild improvement in symptoms from taking a probiotic.
- Benefits may relate to specific symptoms, so benefits observed in one patient profile may not translate to another.
- Trial 1 probiotic product at a time for a minimum of 4 weeks and monitor symptoms. If you notice no improvement after 12 weeks, discontinue use.
- It may take time to see benefits from taking a probiotic – at least 3 - 4 weeks.
- Probiotic supplements should be taken regularly – benefits are not permanent and lost within days if you stop taking a probiotic.
- Consider other ingredients in probiotic products – synbiotics (mixtures of prebiotics and probiotics) often contain FODMAPs, such as inulin or FOS. These may be poorly tolerated in people with IBS.
Our advice is to try one management strategy at a time. Commence a low FODMAP diet first and if you have not achieved good symptom control after 2-6 weeks on the diet, then discuss other management strategies with your dietitian.
If you are interested in trialing a probiotic, speak with your GP or dietitian regarding a suitable probiotic product first (e.g., one that has been researched for IBS). The Alliance for Education on Probiotics also produce a Clinical Guideline to Probiotics Available in USA, which summarises the latest research on probiotic products available in the USA.
Monash University Low FODMAP Certified™ probiotic products can be found in the Monash FODMAP App in the ‘Dietary Supplements’ category.
