DOES YOGURT ENRICHED WITH BIFIDOBACTERIUM-LONGUM AFFECT COLONIC MICROBIOLOGY AND FECAL METABOLITES IN HEALTHY-SUBJECTS

Diet-induced changes in the colonic microflora seem to play a role in colon carcinogenesis. In this study the effects of a yogurt (500 mL/d for 3 wk) enriched with Bifidobacterium longum and 5 g lactulose/L (A) on the fecal bacterial flora and various risk indexes for colon carci nogenesis were tested in 12 healthy volunteers and compared with a con ventional yogurt (B). Increased excretion of bifidobacteria (P < 0.017 ) was found after consumption of both yogurts compared with the prestu dy periods, whereas cultural counts of aerobes and anaerobes were not different. Breath-hydrogen exhalation was elevated and mouth-to-cecum transit time was accelerated in the period of yogurt A ingestion (P < 0.05) whereas no differences were found for ore-anal mean transit time , stool weight and pH, and fecal concentrations of short-chain fatty a cids, bile acids, and neutral sterols. The results generally indicate great stability of the human fecal flora to this kind of dietary inter vention.