EFFECTS OF FISH-OIL ALONE AND COMBINED WITH LONG-CHAIN (N-6) FATTY-ACIDS ON SOME CORONARY RISK-FACTORS IN MALE-SUBJECTS

The effects of fish oil alone were compared with those of fish oil com bined I:I with evening primrose oil rich in long chain (n-6)fatty acid s in a double-blind cross-over study. After administration of fish oil there was a highly significant increase in 20:5 (n-3) (eicosapentaeno ic acid) and 22:6 (n-3) (docosahexaenoic acid) and a significant decre ase in (n-6) fatty acids in plasma phospholipids. After consumption of the fish oil/evening primrose oil mixture, the increase in (n-3) and the decrease in (n-6) fatty acids were considerably smaller Triglyceri des in serum decreased by 36% (P < 0.01) after the fish oil and by 29% (P < 0.05) after the fish oil/evening primrose oil mixture. Atherogen ic index decreased by 12% (P < 0.05) after fish oil/evening primrose o il and by 6% (P = ns) after fish oil alone. This difference was statis tically significant (P < 0.05). Plasma homocysteine was reduced by 10% (P < 0.05) after the fish oil/evening primrose oil mixture and decrea sed 4% (P = ns) after the fish oil alone. Plasma fibrinogen decreased after both oils. The combined oils did not raise plasminogen activator inhibitor-1 (PAI-I) antigen at all, whereas after fish oil there was a 49% (P < 0.05) increase. Fish oil increased the ratio C20:4 to C20:3 , an index of delta-5-desaturase, by 96% (P < 0.001) and reduced the r atio of C20:3 to C18:2, an index of delta-6-desaturase, by 38% (P < 0. 001), whereas the fish oil/evening primrose oil mixture left these ind exes unchanged. A high index of delta-5-desaturase has been found to b e correlated to increased insulin sensitivity. In conclusion, combinat ion of fish oil and evening primrose oil had a more favorable effect o n the atherogenic index and caused no increase in PAI-I antigen. The e ffects on triglycerides and PAI-I of the fish oil and the mixture appe ars to be a result of their (n-3) fatty acid content. (C) Elsevier Sci ence Inc. 1998.