Polyunsaturated fatty acids (PUFAs) are aliphatic monocarboxylic acids with two or more double bonds in any positional arrangement or geometric configuration. Those PUFAs that prevent or relieve the symptoms of dietary deficiency in humans and animals are named, therefore, the essential fatty acids (EFAs).
The EFAs are a group of naturally occurring unsaturated fatty acids of chain length 18,20, or 22 carbon atoms and they contain between two and six methylene interrupted double bonds in cisconfiguration. The fatty acids are essential to the diet of man and all higher animals as they cannot be synthesized de novo from other lipids or from carbohydrates and amino acids. There are two fundamental EFAs, linoleic and α-linolenic acids, from which all others are derived metabolically.1 The essentiality of the PUFAs is related to their capability to incorporate into lipids and to act as a precursor in the formation of prostaglandins.