EFFECTS OF TRANSGALACTOSYLATED DISACCHARIDES ON THE HUMAN INTESTINAL MICROFLORA AND THEIR METABOLISM

The effects of transgalactosylated disaccharide (TD) intake on human f ecal microflora and their metabolism were investigated in 12 Japanese males. TD is a mixture of sugars, galactosyl galactose, and galactosyl glucose, synthesized from lactose through the transgalactosylation re action of Streptococcus thermophilus beta-galactosidase. Volunteers to ok 15 g of the test sugar daily for 6 days. The TD ingestion increased the number of bifidobacteria and lactobacilli, but decreased the numb er of Bacteroidaceae and Candida spp. in the feces. The ratio of bifid obacteria to total bacteria increased from 0.28 to 0.51. TD decreased the fecal concentrations of propionic acid, isobutyric acid, isovaleri c acid, and valeric acid. This sugar also lowered the fecal pH, and th e concentrations of fecal ammonia, p-cresol, and indole. Moreover, a p ositive correlation was found between the concentration of ammonia, an d that of branched-chain fatty acids (isobutyric acid and isovaleric a cid), p-cresol, and indole. All of these compounds are produced from a mino acids through deamination by the intestinal bacteria. The depress ion of amino acid fermentation by intestinal bacteria may be involved in the reduction of fecal ammonia. These results suggest that a part o f the transgalactosylated disaccharides passes into the colon, inducin g changes in the colonic microflora composition, hastening carbohydrat e fermentation, and depressing amino acid fementation in the human gut .