Effect of dietary alpha linolenic acid and gamma linolenic acid on tissue fatty acids in guinea pigs

Huang, Y. S.; Horrobin, D. F.; Manku, M. S.; Mitchell, J.

Guinea pigs were fed regular chow diets supplemented with 5% (by wt) safflower oil, evening primrose oil or linseed oil for 6 wk. The unsaturated fatty acid content of these oils was 78.9% of 18:2n6, 74.1% of 18:2n6, and 9.2% of 18:3n6 or 21.5% of 18:2n6 and 46.9% of 18:3n3, respectively. In comparison with 18:2n6, dietary supplementation with 18:3n6 significantly increased the tissue levels of 18:3n6; and 20:3nb, dietary 18:3n3 significantly elevated the levels of 18:3n3 in plasma and liver lipids. Dietary 18:3n3 also significantly increased 22:5n3 and 22:6n3 in total phospholipids. The tissue levels of 20:4n6 were not affected by either treatment. Apparently both .DELTA.6- and .DELTA.5-desaturation of n-6 fatty acids in guinea pigs are low, and the metabolism of n-3 and n-6 fatty acids may be regulated by 2 different enzyme systems.