Short chain fatty acids are defined as having how many carbon atoms?

• A. 6-12 carbons
• B. 2-4 carbons
• C. 14-18 carbons
• D. 20+ carbons

Answer: (B)

Short chain fatty acids are defined by having 2 to 4 carbon atoms. This short chain length distinguishes them from other fatty acids: medium-chain have 6 to 12 carbons, long-chain 14 to 18, and very long-chain 20 or more. The common examples—acetate (2), propionate (3), and butyrate (4)—are produced in the gut by microbial fermentation of dietary fiber and are quickly absorbed by colonocytes, providing local energy and helping regulate gut health. So, the correct range is 2–4 carbons; the other ranges correspond to different classes of fatty acids.