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Probiotics and the Immune System, New Research

We know that probiotics crank up the immune system, and now we’re starting to learn how.

Probiotic bacteria’s immune enhancing mechanism reported

By Stephen Daniells, 05-Feb-2009

Dutch scientists have reported that the potential immune system enhancing effects of probiotics may be due to an activation of specific genes in the walls of our intestines.

The scientists, led by Professor Michiel Kleerebezem of NIZO Food Research, identified patterns of gene expressions in the cells of the intestinal wall that may trigger mechanism for immune tolerance.

The study is claimed to be the first scientific evidence of how probiotics influence the immune system in humans. The findings are published online in the Proceedings of the National Academy of Sciences (PNAS Online Early Edition).

A potential immune-enhancing effect from probiotic bacteria has been reported by many scientific groups, but the mechanism by how these effects may be occurring has not been elucidated, according to the Dutch researchers behind the new study.

Scientists from Top Institute Food and Nutrition, NIZO food research, Maastricht University, Wageningen UR, and Radboud University Nijmegen performed an in vivo human study in order to investigate the response of certain genes to Lactobacillus plantarum.

The randomised, double blind, placebo controlled, crossover study involved the ingestion of live L. plantarum, heat-killed L. plantarum, or placebo. Biopsies were taken from the duodenum of the subjects and their gene expression pattern analysed.

Using gene expression analysis, Prof Kleerebezem and his co-workers report differences between the expression profiles of people who consumed the live L. plantarum, compared to the heat-killed L. plantarum or placebo.

“Striking differences” in pathways dependent on a protein complex called nuclear factor kappa B (NF-kB) were observed. NF-kB plays an important role in the regulation of the immune system’s response to infection.

“Our in vivo study identified mucosal gene expression patterns and cellular pathways that correlated with the establishment of immune tolerance in healthy adults,” they concluded.

According the FAO/WHO, probiotics are defined as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”.


In terms of boosting immune function, Lactobacillus fermentum was recently reported to boost the immune health of long distance runners, protecting them from respiratory illnesses. The Lactobacillus strain was associated with an enhancement in the activity of T cells, key players in the immune system (Br. J. Sports Med., doi 10.1136/bjsm.2007.044628)

Scientists at the Institute of Food Research (IFR) conducted a human study and reported thatLactobacillus casei Shirota may modulate the immune response to grass pollen, and help hay fever sufferers (Clin. Exp. Allergy, doi: 10.1111/j.1365-2222.2008.03025.x)

An improvement in the immune function of white blood cells in alcoholics has also been reported by a small study by researchers at University College London. This study also used Lactobacillus casei Shirota supplements (J. Hepatology, doi: 10.1016/j.jhep.2008.02.015)

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3 comments posted

I’m a big fan of the KE-99 strain, which negates the need for other strains and has some good research behind it being the bad boy of the probiotic world. Colby Vorland wrote an article for us about it here.

This is the strain in RPN’s Gut Health, which we will have in our store shortly.

Here’s a blurb about it:

The lactobacillus casei sub-species, KE-99, was selected for its superior probiotic qualities. The primary effect of a probiotic is to reduce the likelihood of pathogenic organisms from establishing themselves and infecting the intestinal tract of a host. In order to accomplish this, the beneficial bacterium overwhelm the enteric sites to become the predominant bacterium present, and consume a significant portion of the nutrients which compromise or possibly eliminate the establishment and/or growth of any unwanted bacteria. (Competitive exclusion) In laboratory tests, however, KE-99 has demonstrated the ability to actually remove already established pathogenic bacteria in vitro (example: enterohemorrhagic E. coli 0157:H7). These bacteria often enter the intestinal tract via consumption of contaminated food and/or drink. This remarkable ability to reduce certain forms of pathogenic bacteria in vitro (currently being tested in vivo in swine) is one of the features that sets KE-99 apart as a superior probiotic.

A number of products on the market contain multiple bacterial strains. KE-99 was intentionally formulated with just one highly effective Lactobacillus casei KE-99 strain. A hardy single strain such as KE-99 has been shown to be much more effective than multiple strains because of its superior ability to attach to enteric sites and establish itself while multi-strains compete with each other and are often merely evacuated. The overall benefits of other strains of intestinal bacteria are well known, but they are meaningless unless they can actually attach to the intended site.

Posted by Marc McDougal on Wed, 02/11/2009 – 23:09
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Many yogurts claim to contain

Many yogurts claim to contain L. Casei, but what are some good sources of L. Fermentum and L. Plantarum?
Posted by Anonymous on Wed, 02/11/2009 – 19:47
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Hooray for probiotics studies in humans!

I just read about this study and am so excited to see more probiotics studies on humans. It is one thing to see digestive and immune benefits from experience (as I have with my probiotic supplement), and it only adds to these positive results to understand the “how” behind the results. Gene patterning is still in its early stages, like probiotics research, so the two seem a perfect match for growing up together and working their way into our expanded view of health. Thanks for the report. -Anna M

Posted by Anonymous on Wed, 02/11/2009 – 13:45