An evaluation of probiotic effects in the human gut: microbial aspects. Final Technical report for Food Standards Agency (FSA) project ref G01022

The main objective of this study was to investigate the ability of probiotic strains, commercially available in the United Kingdom, to survive in vitro (laboratory) conditions that mimic human physiological environments of the main compartments of the intestinal tract. The choice of in vitro systems allowed direct comparison between bacterial strains. The strains were screened for survival in the stomach, the small intestine, the large intestine (colon) and their effects on the colonic microflora balance. The screening was selective: only probiotic strains showing a positive response in the considered digestive compartment were selected for assessment in the next digestive compartment. In the beginning 35 strains were isolated from the products, and the test procedures selected a final 7 strains to be tested in a simulated colon for ten days. The probiotic strains did not affect the microflora balance of the indigenous bacteria of the simulated colon. Four of the strains survived the environments of the colon also after feeding of the individual strain to the system had stopped. One of the four strains with the best survival abilities was L. reuteri.

Conclusion: Eleven percent (4/35) of the commercial bacterial strains were able to survive in the screening tests mimicking the human gut environments and processes. L. reuteri was one of these surviving probiotic strains.

Reference

An evaluation of probiotic effects in the human gut: microbial aspects. Final Technical report for Food Standards Agency (FSA) project ref G01022. Gibson GR, Rouzaud G, Brostoff J, Rayment N. (2005) Report text, tables and figures are free to access at http://www.food.gov.uk/news/newsarchive/2005/mar/probiotics