Complex carbohydrate breakdown in the human colon.

Concentrations of water-soluble high- and low-molecular-weight carbohydrates were determined in the intestinal contents of four human subjects who had died accidentally. In all four subjects, concentrations of high-molecular-weight carbohydrate were lower throughout the colon than in the ileum. In some subjects, similar but less dramatic differences were also found with low-molecular-weight carbohydrate. Components of both high- and low-molecular-weight peaks included neutral sugars such as rhamnose, galactose, mannose, xylose, and arabinose, which are found in many plant polysaccharides. Components characteristic of mucins (fucose, hexosamines, and sialic acids) were also detected. These results indicate that dietary fiber and mucin are degraded in the human colon.