Fish oil feeding lowers thromboxane- and prostacyclin production by rat platelets and aorta and does not result in the formation of prostaglandin I3.

It is demonstrated that feeding cod-liver oil to rats leads to a considerable reduction in the formation of platelet TxA2 and of vascular PGI2. No appreciable formation of TxA3 and PGI3 is observed, although arterial thrombosis is depressed and bleeding time is prolonged. These findings contradict the suggested role of prostaglandins of the 3-series in thromboregulation.