Essential fatty acid
Only two fatty acids are essential for humans. When the two EFAs were discovered in 1923, they were called "vitamin F", but in 1929, research on rats showed that the two EFAs are fats rather than vitamins.
Some other fatty acids are "conditionally essential", meaning that they may become essential under some circumstances.
- Robert S. Goodhart and Maurice E. Shils (1980). Modern nutrition in health and disease (6th ed.). Philadelphia: Lea and Febinger. pp. 134–138. ISBN 0-8121-0645-8.
- alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid) Whitney Ellie and Rolfes SR (2008). Understanding nutrition (11th ed.). California: Thomson Wadsworth. p. 154.
- Burr G.O; Burr M.M. and Miller E. (1930). "On the nature and role of the fatty acids essential in nutrition" (PDF). J. Biol. Chem. 86 (587). http://www.jbc.org/cgi/reprint/97/1/1.pdf. Retrieved 2007-01-17.