Omega-3 & the Heart

Omega 3 fatty acids and the cardiovascular disease
fishing for a natural ingredient

Jehangir N Din, David E Newby, Andrew D Flapman
BMJ. January 2004; 328: pp30-35

Various observers have reported how Greenland Inuit have a low mortality rate from coronary disease even though they consume a diet high in fat. Danish investigators Bang and Dyerberg in the 1970s suggested this may be due to the high daily intake of omega-3 essential fatty acids, thereby establishing a link between the two. The growing concern is that our diet in the west is significantly lacking in omega-3s and far too high in omega-6s and saturated fats. Our bodies lack the necessary enzymes to metabolise omega-6s into omega-3s and therefore it is imperative we obtain it directly from oily fish or supplements.

Various trials have evaluated the effects of fish oils paticularly after myocardial infarction. For instance, 2,003 individuals with recent mycardial infarction took part in the Diet and Reinfarction Trial (DART) and were randomised to three dietary interventions. Patients given fish or fish oil (1.5 g daily) showed a 29% reduction of total mortality following a two year period.

Another example is The Gruppo Italiano per lo Studio della Sopravvivenza nell`Infarto Miocardio Prevenzione (GISSI-Prevenzione) trial that gave random treatments to 11,324 patients: either an omega-3 fatty acid supplement (0.85 g EPA + DHA), 300 mg vitamin E or neither. After three and a half years, an evaluation revealed the participants who supplemented with fish oil had a 15% reduced risk of total mortality, stroke and myocardial infarction. The risk of cardiovascular disease clearly dropped by 30% and sudden death by 45% in just 4 months of the trial.

This review mentions that although the mechanisms of action in omega-3 needs to be further investigated, evidence implies that fish oils have a prevalent anti-arrhythmic behaviour. Fish oils can increase the heart rate variability in patients after mycardial infarction, leading to a reduction in the risk of mortality and life-threatening arrhythmia. Higher concentrations have shown to improve dilation of the brachial artery in young adults with heart risks which implies the benefits of omega-3s to endothelial function. In addition, omegas-3s have been shown to improve the structure of atherosclerotic plaques. The plaques in the fish oil group were more stable and anti-inflammatory enhancing its resilience to dangerous encounters.

The review concluded that although the benefits of essential fatty acids and coronary heart disease are clear, further trials are needed to assess the specific effects of EPA versus DHA on the risk of heart disease.