Micro-organisms administered in the benefit of the host: myths and facts

Abstract

Objective: To evaluate the published literature on the potential benefit of micro-organisms on the general well being of the host.

Study design: All published prospective, randomized, placebo-controlled trials with micro-organisms to improve the health of the host were critically reviewed.

Results: According to published data, there is evidence suggesting that Lactobacillus rhamnosus strain GG or Lactobacillus casei strain GG and Saccharomyces boulardii may be of possible benefit for the treatment of several medical conditions. However, published data on the therapeutic effect of other micro-organisms are almost non-existent.

Conclusion: Better designed prospective, randomized, and placebo-controlled studies are needed. Most of the present strains have not been selected in a rational way, but apparently represent rather randomly picked isolates. Although the theoretical advantages of micro-organisms administered to the benefit of the host are extremely interesting and promising, results of clinical trials are disappointing.