Effect of lactic acid bacteria on the intestinal production of lactate and short-chain fatty acids, and the absorption of lactose.

The characteristic fermentation pattern seen with specific saccharides in incubations with pure cultures of Lactobacillus acidophilus and Bifidobacterium bifidum disappeared when incubated in 16.7% fecal homogenate. The productions of lactate and short-chain fatty acids in mixed bacterial-fecal incubations were similar to productions in fecal homogenates without L acidophilus and B bifidum and were mainly associated with the specific mono-, di-, and polysaccharides added to the incubate. B bifidum was cultured from ileostomic contents in eight of nine ileostomists after oral administration (2.4 x 10(10) cells), but did not influence the concentrations and productions of DL-lactate and short-chain fatty acids in the ileostomic outputs and incubates. Large amounts of ingested lactic acid bacteria (4.2 x 10(10) cells) did not ameliorate lactose malabsorption measured by the breath-hydrogen test in 12 lactose malabsorbers. This study shows that ingested lactic acid bacteria are indeed present in the colon, but it does not support the theory that they change the pattern of colonic fermentation or the degree of intestinal lactose malabsorption.