[Survival of Lactobacillus acidophilus and Bifidobacterium sp. in the small intestine following ingestion in fermented milk. A rational basis for the use of probiotics in man].

Oro-ileal intubation was performed in 6 healthy volunteers who ingested, either 100 g of a fermented milk containing 10(8)/g Lactobacillus acidophilus and 10(7)/g Bifidobacterium sp or sterilized fermented milk along with a meal in random order. Lactobacillus acidophilus and Bifidobacterium were counted in the ileal fluid which was aspirated continuously for 8 h, and flow rates were calculated using the constant slow infusion of PEG 4000. After ingestion of fermented milk but not after control, hourly ileal flow rates of Lactobacillus acidophilus and Bifidobacterium increased form 4.8 +/- 0.2 and 4.9 +/- 0.6 to 7.2 +/- 0.3 and 8.0 +/- 0.3, respectively (mean +/- SE log10 CFU). 8.3 +/- 0.2 Lactobacillus acidophilus and 8.8 +/- 0.1 Bifidobacterium were recovered in the ileum which represented 1.5 percent and 37.5 percent of the ingested bacteria, respectively. In conclusion, under usual conditions of fermented milk ingestion, a large number of living Lactobacillus acidophilus and Bifidobacterium pass through the upper gastrointestinal tract and reach the colon.