[Studies on the absorption of carbohydrate and nitrogen sources in elemental diets]

To elucidate more efficient carbohydrate and nitrogen sources in elemental diets (ED), we constructed practical elemental diets in which glucose, maltose, or dextrin were used as carbohydrate sources, and crystalline amino acids (AA), small peptides (SP) or large peptides (LP) were used as nitrogen sources. We studied the absorption of carbohydrate, nitrogen and water in these elemental diets. Dogs were used as two experimental models. The Thirty-Vella loop was used as one model (a 40cm intestinal loop separated from the upper portion of the jejunum) so that the effect of digestive juice could be avoided. In the other model (jejunum fistula) two plastic tubes were indwelled in the upper portion of the jejunum, with the oral one being used for infusion of the ED and the other anal one being indwelled 40cm distal to the oral one and used for sampling of intestinal contents. In both loop models, glucose and maltose were absorbed more rapidly than dextrin. Water and nitrogen were absorbed more rapidly in the maltose-ED than glucose-ED. In another series of the studies where nitrogen sources were compared, SP was most rapidly absorbed in the AA-ED, SP-ED and LP-ED. The water absorption rate of the SP-ED was more than that of the AA-ED. These results suggest that maltose is most suitable for use as a carbohydrate source, and small peptides are most suited as a nitrogen source of the materials examined in the present study.