Clear Effect of Probiotics Demonstrated in Gut of Healthy Adults

In a randomized, double blind, placebo controlled, crossover study, healthy volunteers ingested either live probiotic cells (Lactobacillus plantarum), inactivated cells of the same probiotic, or a placebo.

05/02/09 For the first time, scientific evidence has been obtained on how probiotics affect the activity of our genes in the gut wall. These vital results give insight into the mechanism by which probiotics can affect the immune response. The study was carried out by a group of scientists from Top Institute Food and Nutrition, and working in NIZO food research, Maastricht University, Wageningen UR and Radboud University Nijmegen.

In a randomized, double blind, placebo controlled, crossover study, healthy volunteers ingested either live probiotic cells (Lactobacillus plantarum), inactivated cells of the same probiotic, or a placebo. Gene expression analysis of biopsies from the duodenum has shown clearly the effect of the live probiotic on cellular processes. These processes activate the immune system enabling it to play its protective role (the immune response). The results of this study will be published this week in an article in the Proceedings of the National Academy of Sciences (PNAS Online Early Edition).

Professor Michiel Kleerebezem of NIZO explains that the molecular mechanisms of probiotics are largely unknown. The multidisciplinary approach of TI Food and Nutrition, in which food technologists, gastroenterologists and microbiologists work closely together, provided the opportunity to study the molecular mechanisms of probiotic activity in healthy adults. Gene expression analysis has enabled the scientists to demonstrate the direct effects of probiotics on the intestinal mucosa.

Using the database and  bioinformatics expertise built up in the Nutrigenomics Consortium, which is also part of TI Food and Nutrition, they identified patterns of gene expressions in the epithelial cells that are the trigger mechanism for immune tolerance. This is the first scientific evidence in humans of the mechanism by which probiotics influence the immune system.