Intestinal absorption in the aged.

The difficulties of differentiating functional disorders from organic diseases of the intestinal tract in old age are well known. It is also known that the age-related structural changes of the digestive tract are inconclusive of any functional disorder. This has raised the question whether the process of aging is bound to affect the absorption of d-glucose and the amino acids (gly, ala, val, thr, leu, phe, try, pro, his, lys and arg). The results of the present rat experiments, which have been undertaken under a kinetic approach, indicate that the intestinal carrier affinity to the molecules available for transport declines with aging. This implicates that in the young animal the transport of the absorbed molecules from the intestinal lumen at low (initial) concentrations proceeds at a higher rate than it does in the old animal. The reverse was found to be the case for the basic amino acids.