n-3 Fatty Acids and Serum Lipoproteins: Human Studies

Am J Clin Nutr. 1997 May;65(5 Suppl):1645S-1654S. doi: 10.1093/ajcn/65.5.1645S.


The effects of n-3 fatty acids from fish oils (eicosapentaenoic acid and docosahexaenoic acid) and plant oils (alpha-linolenic acid) on human serum lipids and lipoproteins are reviewed. Studies were included in this review if they were placebo-controlled, crossover, or parallel design studies providing < 7 g n-3 fatty acids/d and with treatment periods of > or = 2 wk duration. Only three studies were available for evaluation of the effects of alpha-linolenic acid on serum lipid concentrations. From these studies it appeared that alpha-linolenic acid (18:3n-3) was equivalent to n-6-rich oils vis-vis lipid and lipoprotein effects. Only when very large amounts of flaxseed oil were fed did the hallmark effect of marine n-3 fatty acids-reduced triacylglycerol concentrations-appear. Thus, in terms of effects on lipoprotein metabolism, the plant-derived n-3 fatty acid is not equivalent to the marine-based acids. More studies using the marine-based acids were examined and summarized. Both crossover (n = 36) and parallel (n = 29) design studies reached the same conclusions: total cholesterol is not materially affected by n-3 fatty acid consumption, low-density-lipoprotein cholesterol concentrations tend to rise by 5-10% and high-density-lipoprotein cholesterol by 1-3%, and serum triacylglycerol concentrations decrease by 25-30%. These effects of marine n-3 fatty acids are now well-established; what remains is to determine the mechanisms behind these effects and, more importantly, their health consequences.

Publication types

  • Review

MeSH terms

  • Cholesterol / blood
  • Clinical Trials as Topic
  • Controlled Clinical Trials as Topic
  • Cross-Over Studies
  • Diet / standards
  • Docosahexaenoic Acids / pharmacology
  • Eicosapentaenoic Acid / pharmacology
  • Fatty Acids, Omega-3 / pharmacology*
  • Humans
  • Lipids / blood
  • Lipoproteins / blood*
  • Randomized Controlled Trials as Topic
  • Research Design
  • Triglycerides / blood
  • alpha-Linolenic Acid / pharmacology


  • Fatty Acids, Omega-3
  • Lipids
  • Lipoproteins
  • Triglycerides
  • alpha-Linolenic Acid
  • Docosahexaenoic Acids
  • Cholesterol
  • Eicosapentaenoic Acid