The Omega-6:Omega-3 ratio: A critical appraisal and possible successor

Prostaglandins Leukot Essent Fatty Acids. 2018 May;132:34-40. doi: 10.1016/j.plefa.2018.03.003. Epub 2018 Mar 20.


The well-known health effects of the long-chain, marine omega-3 (n-3) fatty acids (FAs) has led to a growing interest in the prognostic value that blood levels of these FAs might have vis-à-vis cardiovascular and neurocognitive diseases. The measurement and expression of n-3 FA levels is not straight-forward, however, and a wide variety of means of expression of n-3 FA status have been used in research and clinical medicine. This has led to considerable confusion as to what "optimal" n-3 FA status is. The n-6:n-3 ratio has enjoyed relatively widespread use, but this apparently simple metric has both theoretical and practical difficulties that have contributed to misunderstandings in this field. Just as the once-popular polyunsaturated:saturated FA ratio has largely disappeared from the nutritional and medical literature, it may be time to replace the n-6:n-3 ratio with a newer metric that focuses on the primary deficiency in Western diets - the lack of eicosapentaenoic and docosahexaenoic acids (EPA and DHA). The Omega-3 Index (red blood cell EPA+DHA) has much to recommend it in this regard.

Keywords: Arachidonic acid; Biomarkers; Docosahexaenoic acid; Eicosapentaenoic acid; Linoleic acid; Omega-3 fatty acids; Omega-3 index; Omega-6 fatty acids.

Publication types

  • Review

MeSH terms

  • Arachidonic Acid / blood
  • Biomarkers / blood
  • Cardiovascular Diseases / blood
  • Cardiovascular Diseases / prevention & control
  • Dietary Fats / administration & dosage
  • Dietary Fats / blood
  • Docosahexaenoic Acids / blood*
  • Eicosapentaenoic Acid / blood*
  • Erythrocytes / chemistry*
  • Erythrocytes / metabolism
  • Humans
  • Linoleic Acid / blood
  • Neurodegenerative Diseases / blood
  • Neurodegenerative Diseases / prevention & control
  • Reference Values


  • Biomarkers
  • Dietary Fats
  • Docosahexaenoic Acids
  • Arachidonic Acid
  • Linoleic Acid
  • Eicosapentaenoic Acid