Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut. Groger, D., Mahony, L, Murphy, E. et. al. Gut Microbes 4, 4, 1-15

Gut bacteria are a hot topic in medical circles right now, but few studies have assessed their impact on chronic fatigue syndrome (ME/CFS).  This Irish and Swiss study asked  if  inflammation was present in ME/CFS, and if it was, if a single gut bacteria (Bifidobacteriun infantis 35624) could reduce it. The answers were yes, and yes.

The answers, with some proviso’s, were yes, and yes.



Studies suggest Bifidobacteria can improve symptoms in some diseases

The inflammation/sickness behavior theory  suggesting  increased levels of cytokines and other immune factors cause  fatigue and pain, etc. in ME/CFS makes sense given  the disorders infectious onset and symptoms, but inconsistent study results have given some researchers pause.

This study, however, suggests that three of the big pro-inflammatory actors, all of which could send your symptoms soaring, are  increased in ME/CFS,  and the authors placed ME/CFS in the same class of ‘chronic inflammatory disorders’ as ulcerative colitis and psoriasis.  (One proviso – the ME/CFS patients were not age, sex and BMI matched to the healthy controls (many of whom were probably from a University.) Age, sex and BMI can affect cytokine levels)

Let’s take a quick look at these markers.

  • C-reactive protein (CRP)  – Produced in response to increased levels of pro-inflammatory cytokines such as TNF-a and IL-6, CRP levels reflect systemic inflammation.  Increased CRP levels in a CDC study were associated with reduced physical functioning (SF-36) and depressed mood in ME/CFS. Increased CRP levels in a MERUK study that were associated with markers of cardiovascular risk suggested a  low-grade inflammatory state  is present in ME/CFS.
  • Tumor necrosis factor – TNF-a plays a major role in producing inflammation. Several ME/CFS studies have found increased TNF-a  levels  and others have not. One study  proposed that  a TNF-a  network (IL-2:IFN-γ:TNF-α network)  played a key role in ME/CFS.
  • IL- 6  – a pain producer extraordinaire, one study found increased levels of IL-6 in ME/CFS,and a gene expression study suggested increased IL-6 levels after exercise could contribute to the increased pain after exercise seen in this disorder.

 A Bacterial Boost

Gastrointestinal-SystemCiting evidence that the microbes in the gut actually regulate the immune system outside of the gut,  people with chronic fatigue syndrome  were given sachets containing either Bifidobacterium infantis  35264 (1×1010 CFU viable)  or maltodextrin (5 grams) for eight weeks.  At the end of eight weeks the three cytokine levels were measured to see if inflammation was indeed reduced.

With  B. infantis significantly reducing the levels of all three pro-inflammatory markers, it appeared that eight weeks of B. infantis supplementation did reduce the inflammation present in this disorder.

A look at the charts provided  suggested that a subgroup of ME/CFS patients had particularly large reductions in inflammatory markers while most had moderate to mild reductions.  Enormous reductions in CRP levels, for instance,  found in three or four patients, for instance,contrasted with more moderate reductions in others (and some increases in others).

One question that had to be asked, given the lack of information on symptom improvement, was whether the intervention actually showed up in the patients lives.

Focus on Bifidobacterium infantis

Bifidobacterium infantis 35624 is a commercial probiotic formula produced by Procter and Gamble.  One of the few probiotic strains to undergo testing at the research level, numerous studies have examined B infantis effectiveness in irritable bowel syndrome and other disorders.

According to a probiotics website B. infantis strains produce much higher rates of thiamine, nicotinic acid and folic acid that other Bifidobacterium species. ( A number of different B. infantis strains exist.)

B infantis administration for 8 weeks did not significantly alter gut microbiota in infants but did so in IBS patients  (although symptoms did not improve).  A large 2006 placebo controlled, double-blinded study, however, found that B. infantis was significantly more effective than placebo at improving gastrointestinal symptoms in IBS.   A recent  meta-analysis of probiotic studies in IBS suggest that probiotics can assist with symptoms in that disorder.

A quick drop in B. infantis  levels after the supplementation stopped, however, suggested probiotic administration probably needs to be permanent.   B. infantis improved gastrointestinal symptoms and reduced antibodies in celiac patients but did not affect intestinal permeability.


A small placebo-controlled, double-blinded study suggested that a commercial probiotic (Bifidobacterium infantis 35624) can  reduce inflammatory markers that may  contribute to fatigue and pain in some ME/CFS patients. A chart review indicated a subset of patients had  remarkable drops in inflammatory marker, and most  had mild to moderate reductions. Past studies suggest ongoing B. infantis supplementation is needed to to confer results.

No  information was provided on symptom improvement; we don’t know if B. infantis improved symptoms or not.  Dr. Klimas’ research, however, suggests inflammation after exercise causes much symptomatic distress in ME/CFS.


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