EFFECT OF CHRONIC INGESTION OF A FERMENTED DAIRY PRODUCT CONTAINING LACTOBACILLUS-ACIDOPHILUS AND BIFIDOBACTERIUM-BIFIDUM ON METABOLIC-ACTIVITIES OF THE COLONIC FLORA IN HUMANS

Nine healthy volunteers were studied before, during, and after ingesting a fermented dairy product containing Lactobacillus acidophilus, Bifidobacterium bifidum, and mesophilic cultures (Streptococcus lactis and S cremoris) for 3 wk. Hydrogen and methane productions and fecal β-galactosidase and β-glucosidase activities were measured as indicators of fermentation capacity of the colonic flora. Fecal concentrations of nitroreductase, azoreductase, and β-glucuronidase, which may be implicated in colonic carcinogenesis, were also assessed. Hydrogen and methane productions, fecal β-galactosidase, β-glucuronidase, and azoreductase activities did not change over three 3-wk periods whereas fecal β-glucosidase activity increased (42 ± 6, 91 ± 12, and 40 ± 6 IU/g N, P < 0.01) and nitroreductase decreased (0.87 ± 0.13, 0.54 ± 0.11, and 0.57 ± 0.08 IU/g N, P < 0.05).