[Colonic fermentation in humans: effect of the ingestion of meat associated to milk].

The amount of breath H2 produced for 6 h following the ingestion of 240 ml of milk was used as an index of the rate of colonic fermentation of undigested lactose in 8 lactase non-persistent Guatemalan adults. Treatments in separate days included milk alone, milk with 400 g cooked beef, lactose pre-hydrolyzed milk with the same amount of beef, beef alone and fasting for 6 h. Excess excretion of H2, calculated as the mean area under the curve were 178 +/- 31 ppm h with milk alone, 50 +/- 17 with milk plus beef, -1 +/- 26 with prehydrolyzed milk (p > 0.001). Peak increments of breath H2 followed the same trend: all 8 subjects over 20 ppm with milk alone, 2 with milk plus beef and none with hydrolyzed milk, beef alone or fasting. Thus, cooked beef significantly reduces the rate of appearance of intact lactose in the large bowel of lactase deficient adults.