Figure 1. Biosynthetic pathways for polyunsaturated fatty acid families

A simplified scheme of the biosynthetic pathways for n-3 and n-6 polyunsaturated fatty acid families. *Alternate pathways, proposed by Voss et al. [52] and Mohammed et al. [53] in rat liver and Alvarez et al. [54] in canine retina, involve 24-carbon PUFAs as intermediates in the synthesis of 22:6n-3 and 22:5n-6.