Butyric acid is a short-chain fatty acid (SCFA) formed in the mammalian colon by bacterial fermentation of carbohydrates (including dietary fibre). It is a straight-chain alkyl carboxylic acid that appears as an oily, colorless liquid with an unpleasant (rancid butter) odor. The name butyric acid comes from the Greek word for "butter", the substance in which it was first found. **NMR note.** often overlap with [3-Methyl-2-oxovaleric acid](../80/) Experimental spectrum in Human Metabolome Database: [HMDB0000039](https://hmdb.ca/spectra/nmr_one_d/1047)