Cholic acid metabolism in human fecal cultures during diet supplementation with Lactobacillus rhamnosus GG

Background. Lactobacillus rhamnosus GG is used as probiotic and is thought to have protective properties in the human gastrointestinal tract and in other organs. Enrichment of the bile acid pool with secondary bile acids is common in some hepatic and gastrointestinal diseases and this is considered as a pathogenic element in the disease progression. The aim of this study was to evaluate the effect of probiotic feeding on fecal bile acid biotransformation, particularly on the production of secondary bile acids. Methods. Six normal volunteers were administered 500 g/die of a yogurt preparation containing 4×109 C.F.U. of Lactobacillus rhamnosus GG for 30 days. The 7α-dehydroxylation activity was investigated following addition of cholic acid to the stool samples collected before and after the probiotic feeding. The production of deoxycholic acid and the decrease in cholic acid level were studied. Results. The comparison of biotransformation rate of cholic acid to deoxycholic acid before and after probiotic feeding didn't reach a statistically significant difference, but a strong difference was seen in three of the six subjects, indicating a different behavior in different groups of healthy subjects. Furthermore, the three non responder subjects had a lower fecal 7α-dehydroxylation activity in the stool samples from the pre-treatment collection. Conclusions. These results indicate that subjects with a higher production of secondary bile acids in stools may represent a target group for a larger trial with oral probiotic administration.