n-3 Fatty Acids From Fish or Fish-Oil Supplements, but Not Alpha-Linolenic Acid, Benefit Cardiovascular Disease Outcomes in Primary- And Secondary-Prevention Studies: A Systematic Review

Am J Clin Nutr. 2006 Jul;84(1):5-17. doi: 10.1093/ajcn/84.1.5.

Abstract

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 alpha-linolenic acid) on cardiovascular disease outcomes and adverse events was conducted. Studies from MEDLINE and other sources that were of > or =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 alpha-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.

Publication types

  • Meta-Analysis
  • Review
  • Systematic Review

MeSH terms

  • Cardiovascular Diseases / metabolism
  • Cardiovascular Diseases / mortality*
  • Cardiovascular Diseases / prevention & control*
  • Case-Control Studies
  • Cohort Studies
  • Dietary Supplements
  • Evidence-Based Medicine
  • Fatty Acids, Omega-3 / administration & dosage
  • Fatty Acids, Omega-3 / adverse effects
  • Fatty Acids, Omega-3 / therapeutic use*
  • Fish Oils / chemistry*
  • Fish Oils / metabolism
  • Humans
  • Primary Prevention
  • Randomized Controlled Trials as Topic
  • Retrospective Studies
  • Seafood
  • Treatment Outcome
  • alpha-Linolenic Acid / administration & dosage
  • alpha-Linolenic Acid / metabolism*

Substances

  • Fatty Acids, Omega-3
  • Fish Oils
  • alpha-Linolenic Acid