Why do some foods cause foul-smelling gas?

Lawrence S. Friedman, MD
Bacteria in the gut produce foul-smelling gases when they ferment undigested foods that have not been absorbed in the small intestine. These foods consist mostly of carbohydrates, sugars, and fats. The carbohydrates found in high-fiber foods, such as beans, broccoli, cauliflower, and Brussels sprouts, are the worst culprits. These foods release gases such as methane and hydrogen sulfide, which smells like rotten eggs. The worst odor is related to strong-smelling sulfurs that make up just 1% of flatulence or flatus (gas that escapes from the rectum).

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.