Short-chain fatty acids (SCFAs)

Short-chain fatty acids (SCFAs) are the helpful byproducts your gut bacteria make. The main three are acetate, propionate, and butyrate. They form when anaerobic gut microbes ferment dietary fiber and resistant starch that reaches your colon undigested. Butyrate is the star. It is the favorite fuel for the cells lining your colon. It strengthens the tight seals between those cells and keeps the gut barrier intact. It also blocks gene-silencing enzymes (acting as an HDAC inhibitor) and signals through receptors (GPR41, GPR43, GPR109A) to tune your immunity, appetite hormones, and insulin. Propionate mostly heads to your liver, where it helps with glucose and fat handling. Acetate enters your general circulation. When SCFA production drops, from too little fiber or the loss of key producers like Faecalibacterium prausnitzii and Roseburia intestinalis, it consistently tracks with inflammatory bowel conditions, obesity, and poor blood-sugar control. Turning that link into effective treatments is still a work in progress.

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer