Preventive cardiology
Review
Usefulness of Omega-3 Fatty Acids and the Prevention of Coronary Heart Disease

https://doi.org/10.1016/j.amjcard.2005.07.071Get rights and content

Clinical trial evidence exists that supports a role for the omega-3 polyunsaturated fatty acids in coronary heart disease prevention. However, the results from these clinical trials have varied and were conducted in diverse population groups using several different types of omega-3 polyunsaturated fatty acids, including eicosapentaenoic acid, docosahexaenoic acid, and alpha-linolenic acid (ALA). Thus, we systematically reviewed previously published reports assessing the different types of omega-3 polyunsaturated fatty acid interventions and cardiovascular outcomes. Fourteen randomized clinical trials were included in the review. Six trials were included with fish oil, with 1 large trial (10,000 patients) dominating the analysis. In aggregate, the fish oil trials demonstrated a reduction in total mortality and sudden death without a clinically significant reduction in nonfatal myocardial infarction. The 6 trials with ALA supplements or an ALA-enriched diet were of poorer design than the fish oil trials and had limited power. Many of the trials with ALA involved other changes in dietary components. In aggregate, the ALA trials demonstrated possible benefits in reducing sudden death and nonfatal myocardial infarction, but with wider confidence intervals than in the fish oil trials. In conclusion, the evidence suggests a role for fish oil (eicosapentaenoic acid, docosahexaenoic acid) or fish in secondary prevention because recent clinical trial data have demonstrated a significant reduction in total mortality, coronary heart disease death, and sudden death. The data on ALA have been limited by studies of smaller sample size and limited quality.

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Search strategy

Studies were identified by searching MedLine, EMBASE, and Index Medicus from 1966 to June 2004, as well as the Cochrane Library of references and clinical trials. We included all languages. A search was done with key words, including, omega-3 fatty acids, fish oil, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), gamma-linolenic acid, polyunsaturated fatty acids (PUFAs), flax seed oil, dietary therapy, and cardiovascular disease.

Inclusion criteria

We used several criteria to

Identified studies

Our search identified 2,478 publications with possible relevance. From their structured abstracts, we reviewed 118 for full study analysis. Of these, 14 studies met the inclusion criteria.

Study characteristics

The doses of n-3 PUFA ranged from 0.85 to 4.8 g/day for the studies with EPA and DHA and from 1.0 to 6.3 g/day for the studies with ALA. The Jadad quality scores (Jadad quality rating 0 to 5, with 5 indicating highest quality study) ranged from 1 to 4.6 The included studies had sample sizes ranging from 59 to

Discussion

Despite the heterogeneous nature of the clinical trials reviewed, including significant differences in study quality, a few general conclusions can be made. A clear trend seems to emerge (Table 1) that suggests important differences in cardiovascular outcomes (total mortality, CHD deaths, sudden deaths, and nonfatal myocardial infarction) between omega-3 fatty acid supplementation with fish oil (EPA, DHA) or fish versus supplementation with plant based ALA supplementation.

The 6 fish oil trials

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