The effects of low-dose
cod-liver oil on intimal
hyperplasia of vein grafts were examined in 45 adult mongrel dogs undergoing peripheral arterial reconstruction. Fifteen animals served as the control group, 15 animals were fed a
fish-oil supplement containing 240 mg of
eicosapentaenoic acid daily, and a further 15 animals received 480 mg of
eicosapentaenoic acid daily. Segments of undistended external jugular vein were anastomosed to bilaterally divided femoral arteries. The grafts were harvested at 6 weeks and intimal thickness was measured with a computerized interactive image analyzing system. Serum
cholesterol level, prothrombin time, partial thromboplastin time, bleeding time, and platelet counts were measured before the operation and at 2, 4, and 6 weeks after the operation. Plasma levels of
thromboxane B2 and
prostaglandin F1 alpha and serum levels of
eicosapentaenoic acid were measured before and 4 weeks after the operation. Serum
cholesterol level increased similarly and significantly in all animals. Serum levels of
eicosapentaenoic acid rose proportionately with the oral ingestion of
fish oil but did not affect coagulation parameters. Plasma
thromboxane B2 and
prostaglandin F1 alpha were not significantly affected by the ingestion of marine
oils. Intimal thickness was 39 +/- 5 microns in the control dogs. Ingestion of 240 mg of
eicosapentaenoic acid reduced intimal thickness to 24 +/- 3 microns at 6 weeks (p less than 0.01). Increasing the dose by
a factor of 2 did not decrease intimal thickness further, the intima being 23 +/- 2 microns (p less than 0.005). Our data indicate that small doses of
fish oil will reduce intimal proliferation in autologous vein grafts and that marine
oils may exert their beneficial effects on intimal
hyperplasia by a mechanism other than their known effects on
prostanoid metabolism.