Effect of propionibacteria supplementation on fecal bifidobacteria and segmental colonic transit time in healthy human subjects

Background: Some strains of Propionibacterium have bifidogenic properties a nd enhance gut motility in the animal. However, they are not part of the in digenous fecal flora. This study was designed to assess the digestive survi val of ingested propionibacteria, their bifidogenic properties, and the res ulting changes in colonic transit time in healthy humans. Methods: Eighteen subjects were given 5 . 10(10) CFU propionibacteria/day during 2 weeks. Fe cal concentrations of propionibacteria and bifidobacteria were counted befo re (day -8, day -1), during (day 7, day 14), and after (day 21, day 28) the supplementation. Colonic transit time was measured before and at the end o f the 1st week of supplementation. Results: Basal counts of propionibacteri a were less than 5 log CFU/ml stools. They increased in 15 subjects to (mea n +/- 1 standard deviation) 5.63 +/- 0.71 and 6.37 +/- 0.89 on day 7 (P < 0 .01) and day 14 (P < 0.01) and returned to basal levels on day 21. Basal co unts of bifidobacteria (mean, 7.94 +/- 0.71) increased to 8.39 +/- 0.97 on day 7, 8.36 +/- 0.86 on day 14, and 8.70 +/- 0.95 on day 21 (P < 0.05 from mean basal count) and returned to pretreatment levels on day 28 (7.88 +/- 1 .38). Mean counts of propionibacteria during supplementation and bifidobact eria levels on day 14 were significantly correlated (P = 0.01). Transit tim e did not change in the right colon (17.4 +/- 8.1 h versus 17.3 +/- 8.3 h) or in the rectosigmoid area (12.8 +/- 8.5 versus 13.3 +/- 0.2 h); left colo n transit was significantly slowed (7.0 +/- 5.0 h versus 11.9 +/- 9.4 h; P < 0.05). Conclusions: Part of the ingested propionibacteria were able to su rvive the digestive transit. This supplementation was associated with chang es in segmental colonic motility, yet the mechanisms involved in these chan ges remain unknown.