Acid tolerance and fecal recovery following oral administration of Saccharomyces cerevisiae

Probiotics used in human studies

GOAL

To investigate the literature from 1980 to 2004 for the types of studies and organisms used as probiotics in human studies and diseases.

METHODS

PubMed search for probiotic organisms used in studies from 1980 to August 2004. The data from those papers were evaluated for organisms used, dose, vehicle, frequency, and investigator's report of positive or negative results.

RESULTS

A total of 185 manuscripts were identified. Investigators reported results of both single and multiple organisms in the same manuscript. A single organism was used in 125 reports, and multiple organisms, ranging from 2 to 9, were used in 60 reports. Positive results were reported in 239 clinical situations and negative results reported in 49 in a total of 288 clinical conclusions drawn by the respective investigators. The studies are tabulated in this review.

CONCLUSION

There is a large literature available in credible journals that report benefit of probiotic administration using a wide range of doses, organisms, and clinical situations. Most of the studies are simple reports of a clinical situation and require additional evaluation.

Degradation of phytate by high-phytase Saccharomyces cerevisiae strains during simulated gastrointestinal digestion

Hydrolysis of extracellular phytate (InsP(6)) by high-phytase yeast strains and survival of yeast cells were studied at simulated digestive conditions using yeast peptone dextrose growth medium and wheat gruel as model meals. An in vitro digestion method was modified to better correlate with the gastric pH gradient following food intake in vivo. High-phytase yeast gave a strong reduction of InsP(6) (up to 60%) in the early gastric phase, as compared to no degradation by wild-type strains. The degree of InsP(6) degradation during digestion was influenced by the type of yeast strain, cell density, and InsP(6) concentration. Despite high InsP(6) solubility, high resistance against proteolysis by pepsin, and high cell survival, degradation in the late gastric and early intestinal phases was insignificant. Dependency on pH for phytase expression and/or activity seemed thus to be an important limiting factor. Although further studies are needed, our results show the potential of using yeast as a phytase carrier in the gastrointestinal tract.

Candida albicans and Saccharomyces cerevisiae induce interleukin-8 production from intestinal epithelial-like Caco-2 cells in the presence of butyric acid

Intestinal epithelial cells (IEC) are important in initiation and regulation of immune responses against numerous foreign substances including food, microorganisms and their metabolites in the intestine. Since the responses of IEC against yeasts have not yet been well understood, we investigated the effects of Candida albicans, Saccharomyces cerevisiae, and their cell wall components on interleukin-8 (IL-8) secretion by the IEC-like Caco-2 cells. Live cells of both yeast species stimulated Caco-2 cells to produce IL-8 only in the presence of butyric acid, which is a metabolite produced by intestinal bacteria. S. cerevisiae zymosan and glucan also enhanced IL-8 secretion. Treatment of Caco-2 cells with butyric acid increased the expression of mRNAs coding for Toll-like receptor 1 (TLR1), TLR6 and dectin-1, which recognize zymosan. C. albicans induced more IL-8 secretion and also decreased transepithelial electrical resistance more rapidly than S. cerevisiae. These results suggest that both yeasts in the intestine stimulate the host's mucosal immune systems by interacting with IEC.