Fatty acids are organic acids which are a defining constituents of fats. They are made up of a long, unbranched hydrocarbon chain with an even number of carbon atoms. Fatty acids may be saturated or unsaturated, essential or non-essential.
Fatty acids are absorbed from the diet directly, within the hydrophobic interior of micelles. They may result from the action of lipases on triglycerides. Once taken up by the epithelial cells of the jejunum, short chain fatty acids pass directly into the portal circulation, whereas long chain fatty acids are converted into triglyceride which passes into lymphatics within micelles.
The hydrolysis of body stores of triglyceride by a lipase enzyme produces free fatty acid and diglyceride. This step is rate-limiting and is hormonally controlled.
Effects of free fatty acids are as follows:
- provide energy by oxidation
- high levels of free fatty acids inhibit glycolysis and favour glycogenesis
- inhibits hexose monophosphate shunt
Last reviewed 03/2021