title: Influence of dietary fiber on fecal excretion of volatile fatty acids by human adults.
abstract: The ability of dietary fibers to influence the excretion of volatile fatty acids (VFA) in feces was evaluated in five healthy men. Throughout the 63-day study subjects were confined to a metabolic unit and fed semipurified diets. Each diet was consumed for 9 days. Feces were homogenized, and aliquots were analyzed for VFA by a steam distillation procedure followed by gas-liquid chromatography. Individuals showed wide variability in the extent to which they excreted VFA, and there is evidence of some subject-diet interaction. Acetate, propionate and butyrate were generally present in the ratios of 35:25:20, but the proportion of acetate was increased when xylan and corn bran were consumed. The excretion of VFA during the last 3 days of each metabolic period increased with diet as follows: xylan, fiber free, cellulose, pectin and corn bran. Corn bran caused a significant increase in total VFA excretion over the fiber-free diet. Concentration of VFA in excreted feces (or expressed as percentage of fecal solids) increased by diet in the following order: cellulose, xylan, corn bran, pectin and fiber free. Thus, the concentration of VFA in feces showed no relationship to the total quantity of VFA excreted.
mesh_terms: D000328:Adult; D004043:Dietary Fiber / Q000008:administration & dosage*; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005243:Feces / Q000032:analysis*; D005285:Fermentation / Q000187:drug effects; D006801:Humans; D008297:Male; D010368:Pectins / Q000008:administration & dosage; D014990:Xylans / Q000008:administration & dosage; D003313:Zea mays
chemical_list: D004043:Dietary Fiber; D005232:Fatty Acids, Volatile; D014990:Xylans; D010368:Pectins