Which short-chain fatty acid produced by gut microbiota serves as a major energy source for colonocytes?

• A. Acetate
• B. Propionate
• C. Butyrate
• D. Lactate

Answer: (C)

Short-chain fatty acids produced by gut microbiota from dietary fiber fuel the cells lining the colon. Among them, butyrate is the preferred energy source for colonocytes, providing most of their ATP through oxidation in the mitochondria. This makes butyrate the key substrate that sustains the health and function of the colonic epithelium.

Acetate and propionate are also produced and absorbed, but they primarily enter portal circulation to support energy and metabolic processes in the liver and peripheral tissues rather than serving as the main colonocyte fuel. Lactate is a metabolic intermediate and isn’t the principal energy source for colonocytes.