Linoleic acid versus linolenic acid: What is essential?
1983
Bivins, Brack A. | Bell, Richard M. | Rapp, Robert P. | Griffen, Ward O.
A review of the role of fatty acids in metabolism and an attempt to define what is truly an essential fatty acid is presented. Symptoms of essential fatty acid deficiency (EFAD) in animals are diminished growth, external symptoms, anatomic changes, and physiologic changes. Until 1956, three fatty acids were considered essential to prevent EFAD: arachidonic acid, linoleic acid, and linolenic acid. However, in 1956 a study revealed that arachidonic acid could be synthesized in vivo from linoleic acid, and it has since been regarded as non-essential. Linoleic acid remains accepted as essential because it cannot be synthesized in vivo, and it has a defined metabolic significance. Linolenic acid as an essential nutrient is controversial because its metabolic significance remains unclear. Tissue composition is examined with respect to defining linolenic acid. Despite knowledge of the end-products of linolenic acid metabolism, no convincing and reproducible linolenic acid deficiency has yet been demonstrated. Evidence indicates that excessive intake of linolenic acids may not be advantageous. There is insufficient information on human fatty acid metabolism to make a definitive statement as to the appropriate fatty acid balance required. An optimum ratio of linoleic to linolenic acid should be sought. (kbc)
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