Probiotics – Are they worth the hype?

The ‘Gut Microbiota’ (GM) is the name given to the trillions of microorganisms, mainly bacteria, which live in our large bowel. Whilst the term ‘Gut Health’ has come to mean having a healthy balance of bacteria within your GM, good gut health is more than that – see our Gut Health page.

The GM in the bowel are like plants in a garden, they need to be carefully looked after and the health of the GM depends on how it’s nourished.⁠ The bacteria can become negatively affected by a number of factors including illness, stress, poor diet or antibiotics.

But can you really feed your gut bacteria by eating the yoghurts with probiotics cultures that you see advertised on TV, or by drinking kombucha, or by simply popping a tablet? And what if you have a gut condition?


Probiotics are ‘live microorganisms that confer a health benefit on the person taking them. Some probiotics contain a single strain of microorganism whereas others are a mix, so-called multi-strain probiotics. Intuitively it would seem to make sense that taking extra ‘healthy bacteria’ supplements might improve the mix of bacteria in our GM but the evidence shows that:

  • All probiotics are not the same – single strains and multi strains are different in their effects
  • The ability of a probiotic to ‘take root’ in the gut differs from person to person
  • The probiotic bacteria does not usually stay in the bowel once you stop it – this also varies between probiotic strains


Probiotics are currently promoted and sold as being potentially helpful in a number of conditions: to reconstitute your GM after taking an antibiotic, for IBS, in depression and anxiety, immune-related conditions, to improve energy levels, to aid sleep, to help overweight problems, improve sugar control in diabetes. In general, the evidence to support the use of probiotics in these conditions is very weak – one study shows an effect but the next does not.

When it comes to food products:

“The word ‘probiotic’ is not allowed to appear on products sold within the EU as no health claims have been accepted as proven when the evidence has been assessed by the European Food Safety Authority (EFSA). “ – Which?, March 2021

What if I have a digestive condition?

A recent study compiled the results of over 4,000 patients with IBS treated with numerous different probiotics. This large study (a meta-analysis) suggested that only 1 in 7 people who try a probiotic for IBS see some overall benefit.1

Probiotics helped bloating and flatulence symptoms of IBS more than other symptoms like constipation or diarrhea and multi-strain probiotics are more likely to show some benefit than single strain probiotics. One interesting study suggested that a particular bifidobacteria probiotic might improve mood in patients with IBS, but this requires further research. This would be a great development if realised given the intimate connection between the Gut-Brain-Axis.

After a detailed review, the American Gastroenterological Association concluded in 2020 that there is no evidence that probiotics are beneficial in IBS, Crohn’s disease or in most people with ulcerative colitis.2

A British advisory group was a little less direct in their advice and suggested that it is reasonable to try a multi-strain probiotic for IBS for a month (remember 1 in 7 people might find a benefit) but to stop taking it if no benefit is seen. The evidence to support the use of probiotics in IBS and other digestive conditions is very inconsistent and we don’t recommend them routinely for this reason.

It is important to note that probiotics should be avoided by people who have suppressed immune systems as they are a live bacteria. There is also suggestion that probiotics can carry ‘antibiotic resistance’ genes. These are genes that can be passed between different bacteria and can result in bacteria that cause infections becoming resistant to the antibiotics we use – this would not be good news.

©The Gut Experts 2021


1Systematic review with meta-analysis: the efficacy of prebiotics, probiotics, synbiotics and antibiotics in irritable bowel syndrome. Ford AC, Harris LA, Lacy BE, Quigley EMM, Moayyedi P.Aliment Pharmacol Ther. 2018 Nov;48(10):1044-1060. doi: 10.1111/apt.15001. Epub 2018 Oct 8.PMID: 30294792

2AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders.

Su GL, Ko CW, Bercik P, Falck-Ytter Y, Sultan S, Weizman AV, Morgan RL.Gastroenterology. 2020 Aug;159(2):697-705. doi: 10.1053/j.gastro.2020.05.059. Epub 2020 Jun 9.PMID: 32531291


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