Summary
In the 1980s, observational retrospective studies showed an inverse relation between
coronary heart disease (CHD) and consumption of fish containing fatty acids that belong
to the omega (ω)-3 family. Large case-control studies and prospective intervention
trials consistently showed that ω-3 fatty acids supplementation lowers fatal myocardial
infarction (MI) and sudden cardiac death. By analysing the strengths of the results
of individual studies and how the meta-analyses agree with them, putting together
relevant backgrounds, and identifying open questions, the following findings/directions
emerge. (i) Dietary and non-dietary intake of ω-3 fatty acids reduces overall mortality,
mortality due to MI, and sudden death in patients with CHD; (ii) Fish oil consumption
directly or indirectly affects cardiac electrophysiology. Fish oil reduces heart rate,
a major risk factor for sudden death; (iii) Among patients with implantable cardioverter
defibrillators, ω-3 fatty acids do not reduce the risk of ventricular tachycardia/ventricular
fibrillation and may actually be pro-arrhythmic; (iv) The consumption of ω-3 fatty
acids leads to a 10–33% net decrease of triglyceride levels. The effect is dose-dependent,
larger in studies with higher mean baseline triglyceride levels, and consistent in
different populations (healthy people, people with dyslipidaemia, diabetes, or known
cardiovascular risk factors); (v) Outcomes for which a small beneficial effect ω-3
fatty acids is found include blood pressure (about 2 mmHg reduction), re-stenosis
rates after coronary angioplasty (14% reduction), and exercise tolerance testing.
Major experimental data provide strength (biological plausibility) for these findings,
and define directions for newer clinical trials with ω-3 fatty acids.
Keywords
Prevention - acute myocardial infarction - nutrition