Why Do Farts Smell?

As part of their natural metabolic activities, bacteria produce several gases, including methane and hydrogen sulphide (H2S). These gases are what give farts their distinctive smell.

Although it seems like a pointlessly stinky waste product, hydrogen sulphide is actually an important gastrotransmitter, or signalling molecule within the GI tract. H2S helps regulate processes like GI motility and inflammation, and may keep our epithelial cells healthy. It may even play a role in regulating adipocyte (fat cell) function.

As with all things biological, balance is important. If a person is over-producing H2S, it may be a symptom of an underlying health problem, disrupted colonic bacteria flora, or trouble digesting particular foods.

People who have IBS (irritable bowel syndrome), bloating flatulence, or room clearing gas can do a hydrogen breath test with their doctor to look for problems like:

• difficulty absorbing particular sugars, such as fructose or lactose;
• difficulty absorbing sugar alcohols, such as sorbitol or mannitol;
• intestinal bacterial overgrowth or imbalance (often termed small intestinal bacterial overgrowth, or SIBO);
• poor gastric motility, and/or;
• production of H2S and methane gases