Abstract
Rats were provides with one of the following diets ad libitum; cornstarch (CS), 2.5% psyllium (PS), 2.5% high-amylose cornstarch (HAS) and 2.5% PS+2.5% HAS for 4 weeks. Supplementation of HAS and/or PS into the diets was done at the expense of the same amount of CS. Cecal butyrate concentrations were significantly higher in rats fed the 2.5% HAS diet than in those fed the CS, 2.5% PS and 2.5% PS+2.5% HAS diets. However, butyrate concentrations in rats fed the 2.5% HAS diet decreased along the colon from a proximal to a distal direction, and there were no significant differences in fecal butyrate concentration between the groups fed the 2.5% HAS and CS diets. In contrast, the 2.5% PS+2.5% HAS diet-fed group maintained a higher butyrate concentration throughout the large bowel. Fecal butyrate concentrations in this group were significantly higher than those in the group fed the 2.5% HAS diet. Fecal starch excretion was significantly higher in rats fed the 2.5% PS+2.5% HAS diet than in those fed the 2.5% HAS diet. There was a significant and positive correlation between fecal starch excretion and fecal butyrate concentration. These results suggest that ingestion of PS with HAS increases the butyrate concentration in the distal colon and feces, presumably by controlling the fermentation rate of HAS in the cecum and shifting the fermentation site of HAS toward the distal colon.
