Has the beneficial effect of fish oil on cardiovascular disease disappeared?



Meta-analyses of prospective cohort studies or meta-analyses of randomised controlled trials completed before the year 2002 suggest that the very long chain polyunsaturated fatty acids (VLC n-3 PUFA) characteristic of fish oil significantly reduce the risk of cardiovascular disease. However, randomised controlled trials and meta-analyses of these trials published in the last decade suggest that VLC n-3 PUFA have no effect on the risk of cardiovascular disease. While some of the more recently completed trials can be criticised as they were either uncontrolled or did not have sufficient statistical power a more important factor may be at work. By contrast with the earlier trials, the cardiovascular disease patients recruited for trials carried out in the last decade tend to be treated with statins. Demonstrating additional benefit of VLC n-3 PUFA on cardiovascular disease over and above that conferred by statins is clearly proving problematic.