What are prebiotics?
Not to be confused with probiotics (which are live microbiota), prebiotics are essentially the food for our gut microbes. They are found mostly in plant fibres and are not fully digested by the body. This means they stay in the digestive tract and reach the large colon, or bowel, where they are fermented by our gut microbes, which can lead to a range of health benefits.
Not all fibres are prebiotics. In order to gain prebiotic status, the food has to demonstrate its health benefits via scientific studies.
Examples of foods containing prebiotics include:
There is sound scientific evidence for the benefits of prebiotics including improving blood-sugar control, helping keep the gut microbiome healthy, appetite regulation, helping calcium absorption therefore supporting bone health, and some emerging trials suggesting they can help optimise immunity.
While everyone could benefit from prebiotics, for the majority of people, supplementation is NOT necessary – it’s more beneficial to obtain your prebiotic dose from plant-based foods, as you then get all the additional nutrients and benefits these foods bring.
Prebiotics for those with IBS: what’s the evidence?
For those with IBS, they may not be able to tolerate large quantities of prebiotic foods as they can contribute to gas or bloating. It’s important to include some prebiotic foods in your diet regularly but more is not always better – work with your dietitian to find your tolerance level to reap all the benefits!
Bifidobacteria is a beneficial gut bacteria that is typically lower in number in the guts of those living with IBS. Researchers have therefore been trying to find out if prebiotics may help symptom management in IBS through their ability to increase Bifidobacteria levels.
For those living with IBS, research tends to suggest that tolerance really depends on what type of prebiotic someone takes, the dose and the duration.
A systematic review and meta-analysis by researchers at King’s College London, found that for those with IBS, specific types of prebiotics (inulin-type fructans including inulin and oligofructose) unfortunately have no effect on abdominal pain or bloating, and may even worsen flatulence. However they do increase the number of Bifidobacteria, and were better tolerated when doses were less than 6g per day.
This is good news if you like Dr Megan Rossi’s Bio&Me yogurts, which contain 2g per portion of the prebiotic chicory inulin. You can buy the yogurts at some of the major supermarkets including Ocado and Sainsburys.
Other prebiotics such as GOS (galacto-oligosaccharides), partially hydrolysed guar gum and pectin appear to be better tolerated, and may improve flatulence, abdominal pain and bloating. Whilst initial symptoms of flatulence were increased for the first two weeks of taking a GOS based prebiotic supplement (Bimuno), after three weeks symptoms had subsided suggesting that our gut symptoms may adapt following three weeks of regular consumption. Note that for those following the low FODMAP diet, levels of bifidobacteria decreased with and without the prebiotic supplementation, strengthening the argument that the low FODMAP diet should be temporary, with a structured challenge, reintroduction and personalisation phase. This is discussed in our other blog post here.
Prebiotics can increase beneficial gut bacteria, Bifidobacteria in IBS. At lower doses, galacto-oligosaccharides, partially hydrolysed guar gum or pectin appear to be tolerated for those with IBS. If you’re looking to try a prebiotic supplement consistently consume these for at least three weeks to assess the benefit.
We always recommend seeking support from an IBS specialist dietitian to help you manage your symptoms in a holistic manner, as IBS isn’t a one-size fits all approach.