For your reading pleasure, here are excepts from reliable medical literature and review articles. One of the issues of concern in large population studies is that surrogate targets like blood test results do not always correlate with improved outcomes.
I think this is a promising area but quality outcomes data are limited. As to concentrated supplements, the effectiveness and safety are not sufficiently well known. Comments in square brackets are my $.02.
Then again the initial evidence on estrogens and heart disease was convincing, too. Wrong, but convincing. Tough, tough research to do because of infinite numbers of unrecognized variables lurking in the background when you do population-based studies.
Rich sources of omega-3 fatty acids fatty acids include fatty fish, especially salmon, and plant sources such as flaxseed and , canola oil, soybean oil, and nuts.
Populations with high intakes of omega-3 (n-3) polyunsaturated fatty acids (such as the Eskimos) have low rates of heart disease [but have drastically different diets and lifestyles in many other ways, too.]
A meta-analysis of 11 studies involving 16,806 patients found that, compared to a control diet or placebo, a diet enriched with omega-3 fatty acids or the use of supplements was associated with significant reductions in fatal infarction (risk ratio 0.7, 95% CI 0.8- 0.8 ), sudden death (risk ratio 0.7, 95% CI 0.6-0.9), and total mortality (risk ratio 0.8, 95% CI 0.7-0.9). The benefits were the same for an enriched diet or supplements.
Side effects [dietary supplements, non-prescription]:
Gastrointestinal side effects including nausea, ...abdominal bloating, flatulence, diarrhea, and a fishy aftertaste. The symptoms often limit the use of fish oil.
Omacor - raises LDL cholesterol in significant numbers of patients.
Recommendations — At least two servings of fish per week are recommended to confer cardioprotective effects. The pharmacologic use of fish oils supplements should be restricted to patients with refractory hypertriglyceridemia and periodic monitoring of apolipoprotein B levels is recommended.
Hope this is helpful.