EXCRETION AND DEGRADATION OF DIETARY FIBER CONSTITUENTS IN ILEOSTOMY SUBJECTS CONSUMING A LOW-FIBER DIET WITH AND WITHOUT BREWERS SPENT GRAIN

Excretion of total dietary fiber and dietary fiber components was stud ied in 10 human subjects with ileostomies, consuming in a crossover de sign a low fiber diet (15 g total dietary fiber/d) or this diet supple mented with 62 g/d of brewer's spent grain. food and excreta were coll ected and analyzed on d 2, 3 and 7 of each dietary period. No signific ant differences in excretion of total dietary fiber or dietary fiber c omponents were found on the three days. Excreta from subjects consumin g the low fiber diet contained significantly more total dietary fiber than was ingested (20%, P < 0.01), indicating the importance of endoge nous and microbial material, contributing to the total dietary fiber v alue, in ileostomy effluents. Analysis of specific dietary fiber compo nents showed that this increased excretion was mainly due to fucose, m annose, galactose and uronic acid residues. When the high-fiber diet w as consumed, there was a significantly greater excretion of the same n on-starch polysaccharide residues as for consumption of the low fiber diet, but with a simultaneous decrease in excretion of arabinose, xylo se and glucose residues (12%, P < 0.01), which were the major fiber co mponents in the diet.