(Updated February 2021) by Lee Martin MSc RD
Prebiotics are non‐digestible selectively fermented dietary fibers, found in a range of plant based foods, that specifically promote the growth of one or more bacterial genera in the gastrointestinal tract and therefore provide a potential health benefit to the host. Thus it is important to have prebiotcs in the diet for this reason.
Due to their effect on the gut microbiota prebiotics may improve gastrointestinal symptoms. People with IBS and indeed people without gastrointestinal symptoms may take a prebiotic supplement in an attempt to improve their gut health. Common prebiotics added into foods include inulin and fructooligosaccharides (FOS) which are both oligosaccharides and account for the ‘O’ in the FODMAP acronym.
The problematic factor for people with gastrointestinal symptoms is prebiotics are found in lots of high FODMAP foods in the form of fructans and galacto-oligosaccharides (GOS) (both oligosaccharides) and can trigger gastrointestinal symptoms. Additionally the prebiotics used as supplements e.g. inulin are also very high FODMAP and any beneficial effect of improvements in gut microbiota will be at the detriment of increased gastrointestinal symptoms that can be experience from taking the prebiotic. A recent systematic review of prebiotics in IBS summarised that prebiotics as a whole do not improve GI symptoms but do increase bifidobacteria (Read the research here: Wilson et al, 2019 Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials). It is therefore not a good idea for people with IBS or other functional gastrointestinal disorders to take a prebiotic supplement without giving it some consideration.
There is however one prebiotic supplement that can help reduce IBS symptoms and is suitable on a low FODMAP diet.
The prebiotic called Bimuno has had several studies to assess its efficacy in gastrointestinal disorders and its impact on the gut microbiota. The original study included a group of 44 patients with IBS who took Bimuno for 4 weeks. Bimuno was found to significantly increase levels of bifidobacteria, improve stool consistency and reduce bloating and flatulence (compared to placebo). Read the research here: Silk et al, 2009 Clinical trial: the effects of a trans‐galactooligosaccharide prebiotic on faecal microbiota and symptoms in irritable bowel syndrome (open access)
Bimuno has also been shown to reduce IBS type symptoms (abdominal pain, bloating, flatulence) in the general population. Read the research here: Vulevic et al, 2018 Effect of a prebiotic galactooligosaccharide mixture (B‐GOS®) on gastrointestinal symptoms in adults selected from a general population who suffer with bloating, abdominal pain, or flatulence (open access)
In a study further conducted in Spain the efficacy of Bimuno was compared to a low FODMAP diet. In patients with likely functional gastrointestinal disorders and flatulence symptoms 4 weeks of Bimuno increased the abundance of Bifidobacteria while 4 weeks low FODMAP diet deceased bifidobacteria. Both the low FODMAP diet and Bimuno decreased gastrointestinal symptoms significantly expect for flatulence in the Bimuno group. Two weeks after stopping taking Bimuno the symptom reduction remained although when patients went back to eating high FODMAP foods unsurprisingly their symptoms also returned. Read the research here: Huaman et al, 2018 Effects of Prebiotics vs a Diet Low in FODMAPs in Patients With Functional Gut Disorders (open access)
The research study above has many methodological issues which quite rightly has been highlighted in this straight talking letter from the Monash University research team: Prebiotics Versus Low FODMAP Diet: An Interpretative Nightmare
Finally in a recently published study Bimuno has been used in conjunction with a low FODMAP diet to improve gastrointestinal symptoms of those diagnosed with IBS in an RCT. The group that took Bimuno in combination with a low FODMAP diet had better symptom improvement than those who only did the low FODMAP diet suggesting a synergy between the two therapies. Despite taking the prebiotic Bimuno this did not prevent a decline of bifidobacteria from following the low FODMAP diet for 4 weeks (this may be due to the low dose used). Interestingly this study was also the first to show that even 7 days on a strict low FODMAP diet can significantly impact the GI luminal environment by causing higher stool pH, and lower butyrate production. Read the research here: Wilson et al 2020 β-Galactooligosaccharide in Conjunction With Low FODMAP Diet Improves Irritable Bowel Syndrome Symptoms but Reduces Fecal Bifidobacteria
Take home messages for the prebiotic Bimuno:
- Could be useful at reducing symptoms in the general population with IBS type symptoms without having to change diet or follow a low FODMAP diet
- In those diagnosed with IBS it could be used in conjunction with a low FODMAP diet and make it more effective
- Bimuno may not always improve flatulence symptoms and may not improve levels of bifidobacteria in all those with diagnosed IBS but may improve levels of bifidobacteria in some people with functional gastrointestinal symptoms
Finally remember a short term reduction in FODMAP prebiotics can improve IBS symptoms but can also decrease levels of bifidobacteria. Therefore once the 4 week restriction phase of a low FODMAP diet is complete it is important these FODMAP prebiotic fibres are reintroduced to personal tolerance levels to protect against any unknown long term side effects of long term FODMAP restriction on the gut microbiota.