A new group of essential fatty acids and their comparison with other polyenoic fatty acids

Abstract

1. 1. Polyenoic C 17, acids, mainly 9,12-heptadecadienoic and6,9,12-heptadecatrienoic with some 6,9,12,15-heptadecatetraenoic; polyenoic C 16 acids, mainly 9,12-hexadecadienoic and 6,9,12-hexadecatrienoic; and 10,13-nonadecadienoic acid were fed as methyl esters for 50 days to fat-deficient rats and their effects on fat deficiency symptoms were compared with those of linoleic acid and of fat-free diet. 2. 2. The polyenoic C 17, acids cured the external symptoms nearly as well as linoleic acid. Weight gain and food efficiencies were equal with both acids. Accordingly, fatty acids derived from 9,12-heptadecadienoic acid have essentiality similar to those derived from linoleic acid. The triene/tetraene ratio in liver lipids is applicable as index of essential fatty acid nutrition when modified from 5,8,11-eicosatrienoic/ arachidonic to 5,8,11-eicosatrienoic/5,8,11,14-nonadecatetraenoic acids. 3. 3. Deficiency symptoms increased with polyenoic C 16 and 10,13-nonadecadienoic acids as with the fat-free diet. 4. 4. Fatty acids of the liver were analyzed. 9,12-Heptadecadienoic acid is converted up to 4,7,10,13,16-heneicosapentaenoic acid with 5,8,11,14-nonadecatetraenoic being prominent. Similarly, 6,9,12,15-heptadecatetraenoic acid is converted up to 4,7,10,13,16,19-heneicosahexaenoic acid. Conversion products from other unusual dietary acids were identified but are very minor in amount. 5. 5. Acids which converted readily were also essential and acids which converted only to a minor extent were not essential. Conversion and essentiality may require the same double-bond structure and both properties may be functionally correlated. However, such hypothesis can still be disputed since the essentiality of isomers of arachidonic and similar acids is not yet known.