[Effect of probiotics and yogurt on colonic microflora in subjects with lactose intolerance]

To study the effects of probiotics and yoghurt supplementation on colonic microflora in subjects with lactose intolerance (LI).

Eleven lactose intolerant volunteers determined by 25g lactose challenge test were recruited and given supplementation with Bifina capsule (with B. longum) and yogurt (with B. animalis, L. bulgaricus, S. thermophilus) for 14 days. The trial was divided into 3 phases: 7-day basal period, 14-day supplementation period and 7-day post-supplementation period. Two lactose challenge tests were performed 1 day before and 1 day after supplementation period respectively, and lactose intolerance symptoms were recorded with questionnaires. Five fecal samples were collected during the trial, and total bacteria and several main groups of bacteria in colon were analyzed by fluorescence in situ hybridization (FISH). The shift of Bifidobacterium species population in colon was analyzed by denaturing gradient gel electrophoresis (DGGE).

It was found that LI symptom was alleviated significantly after supplementation (P < 0.05). The amount of total bacteria and the main groups of bacteria (Bifidobacteria, Bacteroides-Prevotella, Eubacteria, Ruminccocc, et al.) was significantly increased during the supplementation period (P < 0.05). The amount of Bifidobacteria during post-supplementation period was significantly higher than that of basal period (P < 0.05), while the amount of other several groups of bacteria decreased. The result of DGGE showed that the extraneous Bifidobacteria species from Bifina capsule and yoghurt could be detected in fecal samples during supplementation period, however there was diversity between volunteers.

It was suggested that extraneous Bifidobacteria in Bifina capsule and yogurt could resist the effect of gastric acid and bile salt, and survive in colon. Supplementation of probiotics and yogurt could influence the colonic bacteria, and increase the number of main groups of colonic microflora, especially for Bifidobacteria, which could play important role in alleviating LI symptoms.