Paradoxical elevation of LDL apoprotein B levels in hypertriglyceridaemic patients and normal subjects ingesting fish oil.

Twenty-three hypertriglyceridaemic patients treated with 15 g/day of a fish oil concentrate (Maxepa) showed the expected reduction in serum triglyceride concentration but levels of LDL apoprotein B (apoB), measured by radial immunodiffusion, increased significantly. Increases in LDL apoB did not correlate with lipoprotein phenotype or changes in serum triglyceride. Studies in eight normal volunteers demonstrated that the effect of fish oil on LDL apoB was not restricted to hypertriglyceridaemic subjects. In view of the evidence that LDL apoB may be a risk factor for coronary heart disease these findings raise questions regarding the use of fish oil in the treatment of hypertriglyceridaemia.