Nine healthy male subjects consumed a daily fish oil supplement providing 2.1 g docosahexaenoic acid (22:6 n-3; DHA) and 0 8 g eicosapentaenoic acid (20:5 n-3; EPA) for 6 weeks. The proportion of EPA and DHA in plasma, erythrocytes, leucocytes and platelet phospholipids was increased by the supplement. Plasma concentration of triacylglycerol and very-low-density-lipoprotein-cholesterol were lowered and those of high-density-lipotrotein (HDL)-and HDL,-cholesterol and apoprotein B were increased. Platelet aggregation and thromboxane B, production induced by collagen were partially inhibited. Both systolic and diastolic blood pressure fell during treatment and rose following withdrawal of the supplement. Statistically significant reductions in erythrocyte counts, packed cell volume and haemoglobin and increases in total leucocyte and monocyte counts occurred with the supplement. Plasma u-tocopherol concentrations fell below the normal range during the period of supplementation. It is suggested that future studies consider components other than EPA in fish oil. Further studies are needed to investigate the extent to which fish oil increases the requirement for antioxidant nutrients.

Influence of n-3 fatty acids on blood lipids in normal subjects. Journal oflnternal Medicine 1989: 225. Suppl. 1 : 99-104.The effects of consuming oils providing alpha-linolenic (ALA). eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were studied in healthy volunteers. A blunted increase in plasma triglyceride was observed in subjects given a test meal containing fish oil compared with olive oil: cholesterol concentrations were not increased: increases in EPA and DHA were seen in all lipid fractions. In longer term supplementation studies, ALA increased EPA. but not DHA in plasma phospholipids : preformed EPA was more effective.The proportion of EPA in platelet lipids increased in a dose dependent manner. EPA or DHA. but not ALA. decreased plasma triglyceride and VLDL cholesterol concentrations. Supplements containing DHA increased HDL and HDL, cholesterol and LDL apoB. Total cholesterol and LDL cholesterol concentrations were unaltered.

The influence of increasing intakes of fish oil on spleen leucocyte phospholipid fatty acid composition and cell-mediated immunity was studied in the mouse using a popliteal lymph node assay technique. The immune response was suppressed by 160 g fish oil/kg diet, hut not by lower doses. The proportion of 20:5n-3 in spleen leucocyte phospholipid increased from 0.14 in the controls to 3.8, 7.2, 8.5 and 9.4% in the animals fed on 25, 50, 100 and 160 g fish oil/kg diet; the proportion of 22:6n-3 increased from 5.1 in the controls to 12.1, 12.2, 12.8 and 12.9% respectively. It is concluded that moderate intakes of fish oil are not immunosuppressive.