Contribution of dietary protein to sulfide production in the large intestine : an in vitro and a controlled feeding study in humans

• Published in: The American journal of clinical nutrition 2000-12, Vol.72 (6), p.1488-1494
• Main Authors: MAGEE, Elizabeth A, RICHARDSON, Caroline J, HUGHES, Roisin, CUMMINGS, John H
• Format: Article
• Language: English
• Subjects: Adult; Amino acids; Amino Acids, Sulfur - metabolism; Biological and medical sciences; Cross-Over Studies; Diet; Dietary Proteins - administration & dosage; Dietary Proteins - metabolism; Feces - chemistry; Fundamental and applied biological sciences. Psychology; Humans; Intestine, Large - metabolism; Intestine, Large - microbiology; Intestine. Mesentery; Large intestine; Male; Meat; Middle Aged; Proteins; Regression Analysis; Sulfates - urine; Sulfides - isolation & purification; Sulfides - metabolism; Vertebrates: digestive system
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/72.6.1488

Hydrogen sulfide is a luminally acting, bacterially derived cell poison that has been implicated in ulcerative colitis. Sulfide generation in the colon is probably driven by dietary components such as sulfur-containing amino acids (SAAs) and inorganic sulfur (eg, sulfite). We assessed the contribution of SAAs from meat to sulfide production by intestinal bacteria with use of both a model culture system in vitro and an in vivo human feeding study. Five healthy men were housed in a metabolic suite and fed a sequence of 5 diets for 10 d each. Meat intake ranged from 0 g/d with a vegetarian diet to 600 g/d with a high-meat diet. Fecal sulfide and urinary sulfate were measured in samples collected on days 9 and 10 of each diet period. Additionally, 5 or 10 g bovine serum albumin or casein/L was added to batch cultures inoculated with feces from 4 healthy volunteers. Concentrations of sulfide, ammonia, and Lowry-reactive substances were measured over 48 h. Mean (+/-SEM) fecal sulfide concentrations ranged from 0.22 +/- 0.02 mmol/kg with the 0-g/d diet to 3.38 +/- 0.31 mmol/kg with the 600-g/d diet and were significantly related to meat intake (P: < 0.001). Sulfide formation in fecal batch cultures supplemented with both bovine serum albumin and casein correlated with protein digestion, as measured by the disappearance of Lowry-reactive substances and the appearance of ammonia. Dietary protein from meat is an important substrate for sulfide generation by bacteria in the human large intestine.