Dietary supplementation with marine fish oil improves in vitro small artery endothelial function in hypercholesterolemic patients - A double-blind placebo-controlled study

Background Marine fish oils improve vascular function, but the mechanism of benefit is unclear. We conducted a study to examine the effects of fish oils given to hypercholesterolemic patients on small artery function in vitro. Methods and Results In a randomized, double-blind placebo-controlled trial, subcutaneous gluteal fat biopsies were taken from 16 hypercholesterolemic patients (serum total cholesterol, 7.97+/-0.16 mmol/L [mean+/-SEM]) and 12 age- and sex-matched control subjects (mean cholesterol, 5.11+/-0.34 mmol/L). Small arteries were mounted on a wire myograph for isometric tension experiments. Patients and control subjects were randomized to receive fish oil (Maxepa 5 capsules BID) or placebo for 3 months. A second biopsy was taken and the studies were repeated. Relaxation to acetylcholine was significantly improved in the hypercholesterolemic group given Maxepa but not in the placebo group (mean maximum relaxation before and after, 48+/-6.2% and 65.83+/-2.19%, P=.0054). The dysfunction was not restored to control values (84.3+/-5.2%, P=.0002). There was also a smaller but significant impairment in endothelium-independent relaxation provoked by sodium nitroprusside (P<.01). A good correlation between the increase in eicosapentanoic acid (n=3) in red cell membrane and improvement in relaxation in the hypercholesterolemic group given fish oils was seen (r=.781; P<.02). Conclusions Marine fish oil significantly improved endothelial function in peripheral small arteries in hypercholesterolemia patients. This may provide a mechanism for the beneficial effects of these fatty acids in coronary heart disease.