Serum lipids in insulin-dependent diabetics are markedly altered by dietary fish oils.

1. The effect of dietary fish oil supplementation on serum lipids was examined in normolipidaemic insulin-dependent male diabetics and healthy controls. Fish oil was given as Max eicosapentaenoic acid (EPA), 15 g daily (equivalent to 2.7 g/day of EPA) for 3 weeks. 2. There was a substantial increase in EPA but a depletion of arachidonic acid content of platelet phospholipids. 3. Diabetics showed a rise in total cholesterol, attributable to increases in low density and high density lipoprotein (LDL and HDL) cholesterol. The rise in HDL cholesterol was largely due to an increase in its HDL2 subclass. Similar changes were found in the healthy men although these were not as marked. A decrease in triglycerides was observed in both diabetics and normal controls. 4. Generally, diabetics showed greater changes in lipid concentrations which may suggest an altered metabolic response to w3 fatty acids. Therefore, the possible detrimental effect of the rise in total cholesterol and LDL cholesterol following fish oil administration may be offset by the increase in the protective HDL2 subclass.