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 over 100 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 may 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 unfavourable strains.
Probiotics may also work by:
- altering fermentation patterns
- changing gut motility (movement of the gut and contents within it)
- reducing visceral hypersensitivity (sensitivity to intestinal pain), and/or
- changing anxiety behaviours and brain activity in IBS.
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
- Duration of follow up
- Symptoms at baseline and IBS sub-type (e.g. IBS-C, IBS-D, IBS-M)
- Background diet
- Outcomes measured
- Variability in baseline microbiota between individuals
What recommendations can be made about the role of probiotics in IBS?
- 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
- 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
- Benefits may take time to occur – up to 3 - 4 weeks
- Take the supplement regularly – benefits are transient and lost within days when therapy ceased
- Consider other ingredients – synbiotics (mixtures of prebiotics and probiotics) often contain FODMAPs, such as inulin or FOS. These may be poorly tolerated in people with IBS.
If you are interested in trialling a probiotic, speak with your GP or dietitian regarding a suitable probiotic product (e.g. one that has been researched for IBS).
