Gut Microbial Fermentation

The human body cannot break down fiber on its own; only gut microbes possess this ability. Gut microbes convert fiber into short-chain fatty acids, effectively turning a carbohydrate into a type of fat. Hydrogen sulfide is responsible for foul-smelling gas; methane, hydrogen, CO₂, and nitrogen are odorless. Gut microbes produce cellulase, an enzyme that breaks down cellulose fiber. Most fermentation occurs in the large bowel under normal conditions. Methane and hydrogen gases produced by gut fermentation are highly explosive; historical surgical procedures using mannitol-based devices caused documented intra-abdominal explosions when these gases were sparked.