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

Am J Clin Nutr. 2000 Dec;72(6):1488-94. doi: 10.1093/ajcn/72.6.1488.


Background: 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).

Objective: 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.

Design: 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.

Results: 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.

Conclusion: Dietary protein from meat is an important substrate for sulfide generation by bacteria in the human large intestine.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amino Acids, Sulfur / metabolism*
  • Cross-Over Studies
  • Diet*
  • Dietary Proteins / administration & dosage
  • Dietary Proteins / metabolism*
  • Feces / chemistry
  • Humans
  • Intestine, Large / metabolism*
  • Intestine, Large / microbiology
  • Male
  • Meat*
  • Middle Aged
  • Regression Analysis
  • Sulfates / urine
  • Sulfides / isolation & purification
  • Sulfides / metabolism*


  • Amino Acids, Sulfur
  • Dietary Proteins
  • Sulfates
  • Sulfides