Fish oil and ischaemic heart disease.

Fish oil products are available with or without prescription and are widely used by patients with ischaemic heart disease (IHD).The interest in fish oils, rich in the long chain n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (n-3 20:5) and docosahexaenoic acid (n-3 22:6), originates primarily from the pioneering work of Dyerberg and Bang.' Prompted by the low incidence of acute myocardial infarction in Eskimos in Greenland they suggested that a very high dietary intake of n-3 PUFA's from marine food offered protection against IHD.They showed that the Eskimos had a beneficial lipid pattern and that their balance between pro-aggregatory thromboxanes and anti-aggregatory prostacyclins was shifted towards an anti-thrombotic state compared with Danes.'There is also evidence from Japan and Holland that dietary intake of fishprotects against IHD.2In the American MRFIT study the daily intake of n-3 PUFA was inversely related to IHD mortality in middle-aged men.3However, no such relation was found in the American Physicians' Health Study.4Experimental studies of atherogenesis and arterial thrombogenesis in various animal species lend some support to the hypothesis that dietary intake of n-3 PUFA's may play a part in primary or secondary prevention of IHD or both.