The team from the Alimentary Pharmabiotic Centre, set up last year at Ireland's University College Cork to investigate bacteria and gut health, found that patients who consumed a malted milk drink containing Bifidobacterium infantis 35624 everyday for eight weeks experienced fewer overall symptoms, abdominal pain and discomfort.
The symptom relief was comparable to that seen with Zelnorm (tegaserod) and Lotronex (alosetron), drugs that have been recently approved for the treatment of irritable bowel syndrome (IBS).
IBS is a long-term condition that usually involves cramping, diarrhoea and constipation. It affects between 10 and 15 per cent of the Irish population and a similar proportion of people in other western countries.
However the precise cause of IBS is not fully understood and there is no cure yet. Treatments are aimed at alleviating symptoms but medication, for those with moderate to severe forms of the disease, does not work for all patients.
Senior author on the new study, Professor Eamon Quigley, who is head of UCC's medical school, said the results "look very good in comparison to pharmacological products".
"We believe we have very significant results. It is at least as effective as lots of available products, and probiotics have a good safety profile too," he told NutraIngredients.com.
In contrast, treatment with another probiotic bacteria, Lactobacillus salivarius UCC4331, also isolated at the Irish centre, appeared to have no more effect on IBS symptoms than a placebo drink.
Both strains, patented by UCC, had shown interesting properties in laboratory studies.
"Previous studies of probiotic preparations have been small and used different probiotics, different doses and different definitions of IBS. Ours is one of the first properly powered trials conducted to accepted standards in this area," Dr Quigley added.
For the study, published in the March issue of Gastroenterology (vol 128, issue 3, pp541-51), 77 people with IBS were asked to drink a malted milk drink every morning. The drink either contained L. salivarius, B. infantis or no added bacteria. The subjects recorded their symptoms.
"Our hypothesis is that low-grade inflammation is a factor in IBS and that certain probiotic bacteria can reduce this inflammation. We have some evidence to support this theory because our paper shows a change in cytokine ratios after the probiotic treatment," said Dr Quigley.
He added that further clinical trials are ongoing and research into the mechanism will also be carried out by the team.
Neither of the strains is currently commercially available but the APC works in partnership with Procter and Gamble and is hoping to bring the bacteria to market in new products.