MONTREAL — Daily ingestion of a probiotic preparation containing a bifidobacterium strain can significantly reduce symptoms and normalize the immune response in patients with irritable bowel syndrome, according to two studies presented as posters at the 13th World Congress of Gastroenterology.
A multicenter study which randomized 362 women with irritable bowel syndrome (IBS) to one of three strengths of an investigational probiotic Bifidobacterium infantis 35624 or placebo daily for 4 weeks showed significant improvement in abdominal pain and discomfort, as well as all other measured symptoms in those taking the medium-strength probiotic formulation.
“The very high dose didn't have an effect because it didn't disperse out of the capsule,” commented lead investigator Peter Whorwell, M.D., a professor of medicine and gastroenterology at the University of Manchester (England). He went on to explain that the effective delivery of probiotic formulations remains a challenge.
“A lot of probiotic preparations are not necessarily bioavailable because they may not be alive, or they may be in a media where they are not dispersing well. So it raises a whole issue about quality. If you just go into a supermarket you don't know what you're getting,” he said in an interview.
In another pilot study, 13 IBS patients and 10 healthy controls received milk containing B. infantis 35624 every day for 3 weeks. Peripheral blood mononuclear cells collected at baseline and after each feeding were cultured for 3 days, either alone or with a stimulant, and cytokine levels were analyzed.
The study found that at baseline, spontaneous production of cytokines from the IBS subjects was no different from healthy subjects, while in vitro stimulation of their peripheral blood mononuclear cells produced a significantly higher level of proinflammatory cytokines and a lower level of anti-inflammatory cytokines.
However, probiotic feeding normalized this proinflammatory immune response in the IBS subjects.
Similar work by the same group comparing treatment with B. infantis 35624 or lactobacillus demonstrated symptom relief and a similar normalization of the proinflammatory response with bifidobacterium but not lactobacillus (Gastroenterology 2005;128:541–51).
This response is suggestive of “an immune-modulating role for this organism, in this disorder,” concluded Liam O'Mahony, Ph.D., lead author, of University College Cork (Ireland).
Both studies were sponsored by Procter & Gamble, which is investigating B. infantis 35624.