Nutritional consequences of the Maillard reaction. The absorption of fructose-L-tryptophan in the large intestine of the rat.

The absorption of fructose-L-tryptophan, an early Maillard reaction product formed from tryptophan and glucose, in the large intestine of the rat was examined. The possible involvement of cecal microflora of the rat in the absorption of fructose-L-tryptophan was investigated. Fructose-L-tryptophan was degraded by the cecal microflora (in vitro) after a 12-hour incubation at 37 degrees. Experiments with rat colonic rings and everted sacs indicated that a passive diffusion of this compound occurs in vitro in the colon of the rat. In vivo absorption was determined by introducing fructose-L-[3-14C]tryptophan directly into the cecum. Twenty percent of the total radioactivity injected was recovered in the urine after 24 hours. Fructose-L-tryptophan was detected in the urine, which suggested that this compound was absorbed by the large intestine but excreted without being metabolized. Approximately 1% of the total radioactivity was recovered in the expired air within 24 hours after injection. The small recovery of fructose-L-tryptophan in feces might indicate that this compound was degraded by the action of microorganisms in the large intestine of the rat.