Short-chain fatty acids (SCFAs) are fatty acids of two to six carbon atoms. Derived from intestinal microbial fermentation of indigestible foods, SCFAs in human gut are acetic, propionic and butyric acid. Butyrate is the main energy source of colonocytes, making them crucial to gastrointestinal health. SCFAs all possess varying degrees of water solubility, which distinguishes them from longer chain fatty acids that are immiscible.
List of SCFAs Lipid number Name Salt/Ester Name Formula Mass(g/mol) Diagram Common Systematic Common Systematic Molecular Structural C2:0 Acetic acid Ethanoic acid Acetate Ethanoate 60.05 C3:0 Propionic acid Propanoic acid Propionate Propanoate 74.08 C4:0 Butyric acid Butanoic acid Butyrate Butanoate 88.11 C4:0 Isobutyric acid 2-Methylpropanoic acid Isobutyrate 2-Methylpropanoate 88.11 C5:0 Valeric acid Pentanoic acid Valerate Pentanoate 102.13 C5:0 Isovaleric acid 3-Methylbutanoic acid Isovalerate 3-Methylbutanoate 102.13 C5:0 2-Methylbutyric acid 2-Methylbutanoic acid 2-Methylbutanoate 2-Methylbutanoate 102.13
Functions SCFAs are produced when dietary fiber is fermented in the colon. Acetate, propionate and butyrate are the three most common SCFAs. SCFAs and medium-chain fatty acids are primarily absorbed through the portal vein during lipid digestion, while long-chain fatty acids are packed into chylomicrons, enter lymphatic capillaries, then transfer to the blood at the subclavian vein.
SCFAs have diverse physiological roles in body functions, affecting the production of lipids, energy, and vitamins. Butyric acid supports large intestine health as the primary energy source for colonocytes – the epithelial cells of the colon. The liver can use acetate for energy.
See also List of carboxylic acids Medium-chain fatty acid (MCFA), fatty acid with aliphatic tails of 6 to 12 carbons, which can form medium-chain triglycerides Long-chain fatty acid (LCFA), fatty acid with aliphatic tails of 13 to 21 carbons Very long chain fatty acid (VLCFA), fatty acid with aliphatic tails of 22 or more carbons Odd-chain fatty acid
References
Further reading A review of the biological properties of SCFA from the Danone Institute via archive.org