Abstract
Excessive hydrogen sulfide (H2S) production from gut microbial metabolism may have clinically important relevance in the pathogenesis of gut disorders, including ulcerative colitis. However, little is known regarding factors that alter its production. Using a newly-designed in vitro gas-profiling technology, the study aimed to verify real-time H2S measurement reproducibility and thereafter, assess its production following exposure to dietary factors and 5-aminosalicylate acid (5-ASA). Measurements of H2S, carbon dioxide, hydrogen and methane measurements were compared between gas-profiling systems. Homogenized slurries were prepared from freshly-passed healthy human feces. Fifty ml slurries were aliquoted into separate fermentation chambers and substrates added including 1 g highly fermentable fructo-oligosaccharides (FOS) or resistant starch Hi-Maize (RS), or minimally fermentable psyllium or sterculia, 1 g cysteine, 0.9 g sodium sulfate or 1.2 mL of 1 M 5-ASA alone or in combinations. H2S release was sampled every 5 mins over 4-h and expressed relative to unspiked controls. RS suppressed H2S production by a mean 89.0 (SEM 4.8)% and FOS by 82.2 (6.2)% compared to <35 (17)% by psyllium and sterculia (p<0.001, two-way ANOVA). Cysteine stimulated H2S production by 1557 (532)%. The addition of FOS to slurries containing cysteine significantly suppressed H2S by 90 (2)% over the addition of 5-ASA (0.3 (2)%, p<0.001). Sulfate and 5-ASA had minimal overall effects. In conclusion, the H2S-profiling technology is a reproducible tool. Production of H2S is greatly enhanced by sulfur-amino acids but not inorganic sulfate, and is effectively suppressed by readily fermentable fibers. These findings inform potential designs of dietary therapies to reduce H2S production in vivo.