n-3 Fatty acids from fish or fish-oil supplements, but not α-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review

• Published in: The American journal of clinical nutrition 2006-07, Vol.84 (1), p.5-17
• Main Authors: Wang, Chenchen, Harris, William S, Chung, Mei, Lichtenstein, Alice H, Balk, Ethan M, Kupelnick, Bruce, Jordan, Harmon S, Lau, Joseph
• Format: Article
• Language: English
• Subjects: alpha-Linolenic Acid - administration & dosage; alpha-Linolenic Acid - metabolism; Biological and medical sciences; Cardiovascular disease; cardiovascular diseases; Cardiovascular Diseases - metabolism; Cardiovascular Diseases - mortality; Cardiovascular Diseases - prevention & control; Case-Control Studies; Clinical outcomes; Cohort Studies; dietary fat; Dietary Supplements; disease prevention; docosahexaenoic acid; eicosapentaenoic acid; Evidence-Based Medicine; Fatty acids; Fatty Acids, Omega-3 - administration & dosage; Fatty Acids, Omega-3 - adverse effects; Fatty Acids, Omega-3 - therapeutic use; Feeding. Feeding behavior; Fish; Fish oils; Fish Oils - chemistry; Fish Oils - metabolism; fish products; food intake; Fundamental and applied biological sciences. Psychology; Humans; linolenic acid; literature reviews; meta-analysis; mortality; myocardial infarction; Primary Prevention; Randomized Controlled Trials as Topic; Retrospective Studies; risk factors; risk reduction; Seafood; stroke; Treatment Outcome; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/84.1.5

Studies on the relation between dietary n-3 fatty acids (FAs) and cardiovascular disease vary in quality, and the results are inconsistent. A systematic review of the literature on the effects of n-3 FAs (consumed as fish or fish oils rich in eicosapentaenoic acid and docosahexaenoic acid or as α-linolenic acid) on cardiovascular disease outcomes and adverse events was conducted. Studies from MEDLINE and other sources that were of >=1 y in duration and that reported estimates of fish or n-3 FA intakes and cardiovascular disease outcomes were included. Secondary prevention was addressed in 14 randomized controlled trials (RCTs) of fish-oil supplements or of diets high in n-3 FAs and in 1 prospective cohort study. Most trials reported that fish oil significantly reduced all-cause mortality, myocardial infarction, cardiac and sudden death, or stroke. Primary prevention of cardiovascular disease was reported in 1 RCT, in 25 prospective cohort studies, and in 7 case-control studies. No significant effect on overall deaths was reported in 3 RCTs that evaluated the effects of fish oil in patients with implantable cardioverter defibrillators. Most cohort studies reported that fish consumption was associated with lower rates of all-cause mortality and adverse cardiac outcomes. The effects on stroke were inconsistent. Evidence suggests that increased consumption of n-3 FAs from fish or fish-oil supplements, but not of α-linolenic acid, reduces the rates of all-cause mortality, cardiac and sudden death, and possibly stroke. The evidence for the benefits of fish oil is stronger in secondary- than in primary-prevention settings. Adverse effects appear to be minor.