Probiotics are unlikely to ease gut problems such as bloating and other digestive complaints, a major review of the evidence suggests.
The supplements – often described as ‘good’ or ‘friendly’ bacteria – contain live micro-organisms which come in pill form or yogurt drinks, and have received heavyweight medical backing that they improve digestive health.
Both the NHS and the British Society of Gastroenterology recommend probiotics to patients suffering with irritable bowel syndrome (IBS), a condition which can trigger stomach cramps, bloating, diarrhoea and constipation. Yet an analysis of 82 previous trials, involving more than 10,000 volunteers, found no good evidence that taking them offers relief.
‘People with IBS are often willing to spend their own money on treatments that could work,’ says Professor Alexander Ford, consultant gastroenterologist at Leeds Teaching Hospitals NHS Trust and co-author of the new study. ‘Because they are looking for a cure they may be misled that probiotics are a panacea, when they aren’t.’
With the supplements available in most supermarkets, the UK’s probiotic market is now worth about £1.4 billion a year and is set to grow by a fifth in the next five years, according to market research firm Mordor Intelligence.
QUICK FIX? Probiotics are available in most supermarkets in the UK
Probiotics contain live micro-organisms that are said to improve the balance of bacteria in the gut that performs a vital role in nutrient absorption
Advocates say taking the supplements supports the immune system, aids weight loss and prevents infections, and previous studies have shown that taking some types of probiotics can improve symptoms of IBS, which affects about 13 million Britons.
Probiotics contain live micro-organisms that are said to improve the balance of bacteria in the gut that performs a vital role in nutrient absorption. The micro-organisms also occur naturally in fermented foods such as yogurt, sourdough bread and sauerkraut.
Having a wide variety of healthy bacteria in the gut has been linked to a host of benefits. Research has shown that some combinations of gut bacteria can send strong fullness signals to the brain – reducing hunger pangs – and also increase mood-boosting hormones.
Supposed improvements in IBS symptoms are said to be due to a number of factors. Animal studies have shown an increase in some strains of gut bacteria can reduce pain signals sent from the gut to the brain, and have also suggested that probiotics can stop the immune system from releasing proteins that trigger gut inflammation.
However, the new review – the first of its kind, published in the journal Gastroenterology – throws these links into question.
Researchers included a mixture of international trials testing a total of 60 products – drinks and pills – some of which are available to buy in high street shops. They also analysed studies involving unbranded capsules of bacterial strains often used in probiotics, such as Lactobacillus and Bifidobacterium.
Gastroenterologists at the Leeds Gastroenterology Institute at St James’s University Hospital honed in on specific IBS symptoms, such as pain, bloating, constipation and diarrhoea, and found the evidence for relief from them was unreliable.
‘Most of the products are tested on too few participants, leaving room for error,’ says Prof Ford.
‘Probiotics are often classed as food supplements, so are not subject to the rigorous investigations that drugs are. As these products are already out there and making money, there is no incentive to carry out high-quality trials, which would be expensive to undertake.’
Dietician Dr Duane Mellor said: ‘For IBS, simple changes such as eating slower and when sitting up straight, and controlling stress, are more likely to ease symptoms than probiotics – and they are free.’
But Professor Glenn Gibson, researcher in food microbiology at the University of Reading, is more optimistic. ‘There are good studies showing that Bifidobacterium [found in many UK products] can ease IBS symptoms,’ he says. ‘Gastroenterologists are used to seeing big benefits with drugs, so their expectations may be too high.’
Catherine Harland, from Newcastle, has suffered from IBS since her early 20s. ‘I’ve had accidents in shopping centres because I couldn’t get to the toilet in time,’ says the 53-year-old. ‘I’ve got no underlying problems, so I’ve had to do my own research into what might help.’
In 2021, her daughter recommended she try probiotics, having read about the benefits online. But after taking them for a month, Catherine saw no difference.
Following a bad flare-up in April last year, she tried probiotics again, spending £65 on a month’s supply.
‘I saw a slight improvement but I think it’s because I cut trigger foods out of my diet,’ says Catherine.
By February, her gut trouble had returned with a vengeance. ‘I was running to the toilet about five times each day,’ she says. ‘I realised that the probiotics were quite literally just money down the drain.’
Over the past six months, Catherine has changed her daily routine, which has offered some relief.
‘I’ve tried to de-stress with lots of walks in the countryside. I’m eating more healthily and I’ve stopped drinking alcohol like a fish at weekends,’ she says.
‘It’s not exactly where I want to be, but it does seem a lot better.’