Could Bacterial Sulfide Gas Be a Trigger for Ulcerative Colitis?

This 1996 paper from the Medical Research Council’s nutrition centre in Cambridge gave a name and a clear framing to one of the most important ideas in gut science: that a gas made by ordinary gut bacteria might help cause ulcerative colitis. The authors deliberately ended their title with a question mark, signaling a hypothesis to be tested rather than a settled fact.

The sulfide hypothesis

Building on earlier work showing that colon cells in ulcerative colitis struggle to use butyrate — their preferred fuel — Pitcher and Cummings proposed a bacterial culprit. Sulfate-reducing bacteria, chiefly Desulfovibrio, live in the colon and release hydrogen sulfide (H2S) as a by-product. The authors argued that this sulfide interferes with the colon cells’ ability to burn butyrate, effectively starving the gut lining of energy.

Several strands of evidence supported the idea:

• People with ulcerative colitis tend to carry more sulfate-reducing bacteria and produce more sulfide than healthy people.
• Dietary sulfate — abundant in processed foods, meat and eggs — feeds these bacteria, so a Western diet drives their activity.
• In animal studies, short-chain fatty acid enemas protected the gut lining, but sulfide exposure reversed that protection.

Why it became a landmark

The paper connected three things that had been studied separately — diet, specific gut bacteria, and inflammatory bowel disease — into a single coherent mechanism. It has been cited hundreds of times and prompted a wave of experiments, many of which confirmed that sulfide does indeed impair the colon’s use of its main fuel.

“Hydrogen sulphide: a bacterial toxin in ulcerative colitis?”

For everyday gut health, the practical message is hopeful: because the sulfide-making bacteria depend on dietary sulfate, diet is one lever that may influence this pathway.