Acyl group distributions in tissue lipids of rats fed evening primrose oil (λ-linolenic plus linoleic acid) or soybean oil (α-linolenic plus linoleic acid).

Three groups of rats were fed diets with either 10 weight percent (wt%) of evening primrose oil, safflower oil or soybean oil for 11 weeks. Diets contained 7.1 wt% linoleic acid +0.8 wt% γ-linolenic acid, 7.6 wt% linoleic acid, or 5.3 wt% linoleic acid +0.7 wt% α-linolenic acid, respectively. In liver mitochondria as well as in heart, dietary γ-linolenic acid did not affect the fatty acid profiles of phosphatidylcholnes (PC), phosphatidylethanolamines (PE) or cardiolipins (CL), whereas dietary α-linolenic acid caused an increased formation of (n-3) polyunsaturated fatty acids (PUFA). The liver Δ6- and Δ5-desaturase activities determined in vitro were not affected by the dietary fats. In brain PE, which are rich in C22- and C20-(n-3) PUFA, as well as in testes PC and PE, which are rich in (n-6) PUFA, no effects were found from a partial replacement of dietary linoleic acid with γ-linolenic acid or α-linolenic acid. In kidney PC, PE, phosphatidylinositol (PI) and CL, 20∶3(n-6) was moderately elevated to ca. 1% following intake of γ-linolenic acid, whereas partial replacement of linoleic acid with α-linolenic acid was followed by increased deposition of 22∶6(n-3) in PC and PE of testes and kidney. Thus, no general effect of evening primrose oil on the content of (n-6) PUFA in rat tissue phospholipids was observed, wheras a significant incorporation of γ-linolenic acid into liver and adipose tissue triglycerides was found.