Effects of coingestion of different fibers on fecal excretion and cecal fermentation in rats

The effects of the concurrent ingestion of 2 dietary fibers of different fermentabilities on fecal excretion and cecal fermentation were examined in rats. Poorly fermentable, low-molecular-weight sodium alginate supplementation of a fiber-free diet increased fecal excretion and the water content dose-dependently but did not affect cecal pH. Highly fermentable guar gum hydrolysate supplementation decreased cecal pH dose-dependently, whereas there was only a slight increase in fecal excretion. The concurrent ingestion of both fibers increased fecal excretion, lowered cecal pH, and increased the fecal water content and cecal short-chain fatty acids, especially butyrate. The increases in both fecal excretion and cecal fermentation were not achieved by excessive ingestion of the respective fibers alone and were also observed in loperamide-induced constipation. In conclusion, the concurrent ingestion of low-molecular-weight sodium alginate and guar gum hydrolysate increases both fecal excretion and cecal fermentation as a consequence of each fiber compensating for their respective dietary disadvantages in a complementary manner.