Evolutionary Aspects of the Dietary Omega-6/Omega-3 Fatty Acid Ratio: Medical Implications

  • Artemis P. SimopoulosEmail author
Part of the Advances in the Evolutionary Analysis of Human Behaviour book series (AEAHB)


Several sources of information suggest that humans evolved on a diet with an equal ratio of omega-6 (ω-6) to omega-3 (ω-3) fatty acids, whereas in today’s Western diet, this ratio is ~10:1 to 20–25:1. From an evolutionary perspective, Western diets are thus deficient in ω-3 fatty acids. This is problematic as while ω-3 and ω-6 fatty acids are important components of practically all cell membranes, they are not interconvertible in the human body. Moreover, a balanced ratio of ω-6 to ω-3 fatty acids is required for homeostasis and normal development. Excessive amounts of ω-6 polyunsaturated fatty acids (PUFAs) and a very high ω-6/ω-3 ratio, as is found in today’s Western diets, promote the pathogenesis of many diseases including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. On the contrary, increased levels of ω-3 PUFA (a lower ω-6/ω-3 ratio) exert suppressive effects. We thus recommend that ω-3 and ω-6 fatty acids should be distinguished on food labels because they both are metabolically and functionally distinct and have opposing physiological effects. We further argue that a lower ratio of ω-6/ω-3 fatty acids is desirable as it is likely to reduce the risk of many of the chronic diseases of high prevalence in Western societies, as well as in the developing countries.


Omega-6/omega-3 fatty acid ratio Physiological aspects Opposing metabolic effects Genetic variation Cardiovascular disease and cancer 



Essential fatty acids (EFA)

Fatty acids that human and other animals must ingest because the body requires them for good health but cannot synthesize them

Polyunsaturated fatty acids (PUFAs)

Fatty acids that contain more than one double bond in their backbone

Linoleic acid (LA)

An EFA ω-6 fatty acid found in corn, sunflower, cottonseed, safflower, soybean, and other vegetable oils

Alpha-linolenic acid (ALA)

An EFA ω-3 fatty acid found in nuts, rapeseed, flaxseed, perilla, canola, and chia oils

Arachidonic acid (AA)

A PUFA ω-6 fatty acid

Eicosapentaenoic acid (EPA)

A PUFA ω-3 fatty acid

Docosahexaeboic acid (DHA)

A PUFA ω-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, sperm, testicles, and retina

Fatty acid desaturase 1 (FADS1)

An enzyme that in humans is encoded by the FADS1 gene

Fatty acid desaturase 2 (FADS2)

An enzyme that in humans is encoded by the FADS2 gene


The group of genes that a progeny inherits from one parent


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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.The Center for Genetics, Nutrition and HealthWashington, DCUSA

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