title: Resistant starch lowers fecal concentrations of ammonia and phenols in humans.
abstract: We investigated the effect of resistant starch (RS) on markers of colonic protein metabolism. Eleven subjects participated in a randomized crossover study in which they consumed either high-RS (39 +/- 3 g/d, -chi +/- SEM) or low-RS (5 +/- 0.4 g/d) diets for 3 wk. All other macronutrients were kept constant. During the high-RS diet daily excretion of fecal nitrogen increased from 1.84 +/- 0.15 to 2.86 +/- 0.42 g/d (P < 0.01) and excretion of fecal phenols fell from 9.2 +/- 1.4 to 5.3 +/- 0.8 mg/d (P < 0.01). Fecal concentrations of ammonia decreased from 397 +/- 33 to 278 +/- 49 microgram/g (P < 0.01) and phenols decreased from 69 +/- 8 to 39 +/- 10 microgram/g (P < 0.001). Daily output of urinary ammonia, urea, phenols, and total nitrogen did not change significantly, but pH decreased from 6.4 +/- 0.1 to 6.2 +/- 0.1 (P < 0.05) during the high-RS period. These results suggest that RS significantly attenuates the accumulation of potentially harmful byproducts of protein fermentation in the human colon.
authors.affiliation: School of Nutrition and Public Health, Deakin University, Malvern, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Birkett
authors.forename: J
authors.initials: J
authors.lastname: Muir
authors.forename: J
authors.initials: J
authors.lastname: Phillips
authors.forename: G
authors.initials: G
authors.lastname: Jones
authors.forename: K
authors.initials: K
authors.lastname: O'Dea
mesh_terms: D000328:Adult; D000641:Ammonia / Q000032:analysis* / Q000652:urine; D003106:Colon / Q000187:drug effects / Q000378:metabolism; D003404:Creatinine / Q000652:urine; D003408:Cresols / Q000032:analysis; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000378:metabolism; D005243:Feces / Q000737:chemistry*; D005260:Female; D005285:Fermentation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000032:analysis / Q000652:urine; D010636:Phenols / Q000032:analysis* / Q000652:urine; D013213:Starch / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D014508:Urea / Q000652:urine
chemical_list: D003408:Cresols; D004044:Dietary Proteins; D010636:Phenols; C032538:4-cresol; D000641:Ammonia; D014508:Urea; D013213:Starch; D003404:Creatinine; D009584:Nitrogen