A new study shows that a probiotic available commercially in the US for fortifying the digestive system, has effects beyond the gastrointestinal tract: it may also have effects against non-gut inflammation such as in psoriasis and chronic fatigue syndrome (CFS).

The study, published in the latest issue of the journal Gut Microbes is thought to be important because it is the first to show a single probiotic can influence not only the mucosal immune system but also the systemic immune system in humans.

The mucosal immune system protects the internal mucosal surfaces of the body such as the gastrointestinal, urogenital and respiratory tracts. These internal surfaces act as a barrier to the outside world for the internal tissues of the body, which are then further protected by the systemic immune system.

There is some convincing evidence that probiotics, or gut-friendly bacteria, influence the development and maintenance not only of the microbial balance inside the gut and the mucosal immune system but also the systemic immune response.

The name of the probiotic in this new study is Bifidobacterium infantis 35624, which was discovered in the early 1990s by microbiologists at Alimentary Health, a development biotech based in Cork, Ireland, in partnership with Procter and Gamble.

The gut-friendly bacterium is the main ingredient in Procter & Gamble’s Align dietary supplement which is commercially available in the US.

The new study, which was conducted by scientists from Alimentary Health and the Alimentary Pharmabiotic Centre at University College Cork, includes three separate randomized, double-blind placebo-controlled trials of the effect of the probiotic in both gastrointestinal and non-gastrointestinal related disorders.

For the trials, the team recruited 22 patients with the gastrointestinal disorder ulcerative colitis (UC), 26 patients with the inflammatory skin condition psoriasis, and a further 48 patients with chronic fatigue syndrome (CFS), another inflammatory disease.

There was also a group of 35 healthy volunteers. These were used as baseline references for levels of inflammation markers in the patients and some went on to take part in the trial itself.

At the start of the study, all patients (with gastrointestinal UC, and non-gastrointestinal CFS and psoriasis) had significantly raised levels of three blood biomarkers for inflammation compared to the controls.

The three biomarkers were C-reactive protein (CRP) and the pro-inflammatory cytokines, tumor necrosis factor alpha (TNF-a) and interleukin-6 (IL-6).

During the trial period, which lasted between 6 and 8 weeks, each patient and 22 of the healthy controls received identical sachets containing either the probiotic or a placebo.

At the end of the trial, the researchers found that compared with the controls:

  • All three groups of patients who received the probiotic had significantly lower levels of CRP compared with placebo.
  • However, only CFS and psoriasis patients showed reductions in TNF-a, and only UC and CFS patients showed reductions in IL-6.

The researchers explain that the levels of inflammatory marker reduction seen in the trial usually count as remission and indicate a lower risk of relapse.

The researchers say their paper is the first to show a probiotic resulting in consistent reductions in a number of inflammation markers across a range of conditions, gastrointestinal and non-gastrointestinal. Moreover, the findings also show the extent to which B. infantis 35624 in particular can affect the human immune system.

Co-author Professor Eamonn Quigley, chief of the gastroenterology and hepatology division of Houston Methodist Hospital in Texas, said:

“Some probiotics alter the immune system in animal studies but few translate the effects to humans.

What is impressive about these results is that not only are they from human subjects, but from individuals with common inflammatory conditions.”

Prof. Quigley, who is also of Weill Cornell College of Medicine in Houston, adds that the study raises the “exciting prospect” of using specific probiotics to influence the immune system from inside the gut.

In 2009, a study found that out of 13 different individual strains or preparations reviewed, B. infantis 35624 was the only one that signficantly improved IBS symptoms.

Written by Catharine Paddock PhD