Previous randomised controlled trials of marine omega-3 (n-3) fatty acids have been inconclusive. The recent REDUCE-IT study in patients with or at high risk of cardiovascular disease found a highly significant positive clinical outcome with highly purified eicosapentaenoic acid ethyl ester. Another recent study, the VITAL study, used marine n-3 fatty acids but showed negative results. The VITAL study was much larger but it was a primary prevention study, whereas the participants in the REDUCE-IT study had a much higher risk. The formulation of n-3 fatty acids was different between the two studies—the active comparator n-3 fatty acid arm in the VITAL study included a mixture of eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). In addition, there was a considerable difference in the dosing between the two trials. Therefore, whether these factors account for differences in results is conjectural. Beneficial effects of alpha linolenic acid (ALA) of plant origin on vascular inflammation, thrombosis, arrhythmogenesis and vascular events also remain inconclusive.