Beneficial Effect of Dietary Fiber on the Upper Gastrointestinal Transit Time in Rats Suffering from a Toxic Dose of...

Gobo dietary fiber (GDF) obtained from the roots of edible burdock (Arctium lappa L.) was examined for its protective role against amaranth (Food Red No. 2, Am) toxicity in the upper gastrointestinal tract (from the mouth to the ileal end) of rats. Ileorectostomized rats were examined for their growth response to feeding with a purified basal diet containing 4% Am with or without 7.5% GDF. The transit half-time (TT50) through the upper gastrointestinal tract was also examined with ileostomized rats by recovering the small intestinal contents from the ileal end, using Cr-EDTA as a nonabsorbable water-soluble marker. Although feeding Am to the ileorectostomized rats resulted in a 50% mortality, concurrent feeding of Am and GDF not only protected the rats from death but also significantly promoted their growth rate when compared to the effect on the survivors fed only with the Am-containing diet. The results of TT50 measurements on ileostomized rats showed that the TT50 was decreased by half in the presence of Am, but was restored to the value for the control without Am when the Am-containing diet was supplemented with GDF. These and previous rsults imply that Am toxicity develops mainly in the upper gastrointestinal tract as a result of decreased availability of nutrients that is produced by the rapid transit and inhibitory effect of Am on the digestion-absorption process. The beneficial effect of GDF appears to be in normalizing the rapid transit through the upper gastrointestinal tract of chyme containing Am and not in the cecum or colon.