Colonization and immunomodulation by Lactobacillus reuteri in the human gastrointestinal tract

This was an open study with the objective to investigate the colonisation of Lactobacillus reuteri, as detected by the genebased so-called FISH method, as well as effects on the immune system.

10 healthy subjects and 9 with ileostomy ingested Lactobacillus reuteri ATCC 55730 in a tablet (4 x 10^8 CFU daily) for 28 days. Tissue samples (biopsies) were taken from the gastric mucosa and from the first part of the small intestine (the duodenum) in 10 of the subjects and from the distal part of the small intestine (the ileum) in 9 of the subjects. The biopsies were taken prior to the start of Lactobacillus reuteriintake and after 28 days’ of intake.

At the end of the study period, all 10 healthy subjects were colonized in the stomach and/or duodenum. All 6 subjects in whom a biopsy could be taken from the ileum (of 9 with ileostomy) were colonized. Stool samples also verified colonisation, up to 2 to 4 weeks after the last day of Lactobacillus reuteri intake. Effects on the immune system in the intestinal mucosa were shown as a significantly increased number of B lymphocytes (CD20-positive cells) in the duodenum and the number of T lymphocytes (CD4-positive cells) in the ileum.

Conclusion: Dietary supplementation with Lactobacillus reuteri induces a significant colonisation of the stomach, duodenum and ileum of healthy humans, and this is associated with significant alterations of the immune response in the gastrointestinal mucosa.



Valeur N, Engel P, Carbajal N, Connolly E, Ladefoged K. Colonization and immunomodulation by Lactobacillus reuteri ATCC 55730 in the human gastrointestinal tract. Appl Environ Microbiol 2004;70:1176-1181.

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