Effects of short-chain fatty acids on human rectosigmoid mucosal colonocyte brush-border enzymes.

Short-chain fatty acids produced by bacterial fermentation of dietary fiber may provide a tonic stimulus to colonocyte differentiation that contributes to the protective effect of fiber against colorectal malignancy. Since brush-border enzymes are common markers of colonocytic differentiation, we compared the effects of equimolar (10 mmol/L) concentrations of the three most common short-chain fatty acids, acetate, butyrate, and propionate, on the alkaline phosphatase and dipeptidyl dipeptidase specific activity of human colonic mucosal biopsies obtained from normal volunteers. Only butyrate significantly stimulated alkaline phosphatase specific activity (50.4% +/- 18.6%, P < .05). Short-chain fatty acid stimulation of dipeptidyl dipeptidase did not achieve statistical significance. Fibers yielding high colonic butyrate levels could have different effects on human colonic mucosal differentiation.