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Posted July 2010
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Omega-3
Essential Fatty Acids

by Joseph J Collins, RN, ND.

Omega-3s are one group of polyunsaturated fatty acids (PUFA) that are important for optimal health. Other PUFAs include omega–6 and omega–9 fatty acids. Omega–3 and omega–6 are essential fatty acids, while omega-9 PUFAs can be made from unsaturated fats.

In the typical Western diet the ratio of omega–6 to omega-3 essential fatty acids is typically as high as 151 to 16.7:1. This high omega-6/omega-3 ratio promotes the pathogenesis of many diseases, including cardiovascular disease, cancer, depression, and inflammatory and autoimmune diseases.1,2,3, A lower ratio improves tissue function and controls many disease states. For instance, ratio of 5:1 had a beneficial effect on patients with asthma, whereas a ratio of 10:1 had adverse consequences.4 A ratio of 2-3:1 suppressed inflammation in patients with rheumatoid arthritis. A ratio as low as 1.4:1 has been recommended for infants.5 Omega-3 fatty acids have anti-inflammatory effects, and reduce production of IL-1 beta, IL-2, IL-6 and TNF-alpha (tumor necrosis factor-alpha), whereas omega-6 fatty acids significantly increase the production of pro-inflammatory cytokines, like TNF-alpha.6,3 Because inflammation is at the base of many chronic diseases, inadequate levels of omega-3 fatty acids play an important role in the manifestation of many diseases, particularly in persons with genetic variation, as for example in individuals with genetic variants of delta-6-desaturase & delta-5-desaturase.7 Important omega-3 fatty acids in nutrition are: linolenic acid (18:3n-3; ALA), stearidonic acid (18:4n-3; SDA) eicosapentaenoic acid (20:5n-3; EPA), and docosahexaenoic acid (22:6n-3; DHA). The polyunsaturated fatty acid-linolenic acid occurs in high concentrations in flax seed, chia seed and perilla seed8,9,10. Stearidonic acid is a minor omega-3 fatty acid in fish, making up only about 0.5-2% of total fatty acids11, but occurs in echium seed as 12.5% of total fatty acids.12 Omega-3 highly unsaturated fatty acids (HUFA, >= 20 carbons and >= 3 carbon-carbon double bonds) include EPA and DHA, which may be synthesized from PUFAs or provided in oils from fish such as salmon, herring, mackerel, anchovies and sardines.

Omega-3 fatty acids are polyunsaturated fats that the body cannot synthesize, but are essential for proper structure and function of multiple body systems. Unsaturated fats have less hydrogen molecules than saturated fats, and provide fewer calories, but are more active in various physiological processes including cell signaling, and cell membrane function and control of inflammation. Biochemically, omega-3 fatty acids are a family of polyunsaturated fatty acids which have their final double bond on the third carbon from the end, or the terminal (n) carbon bond. This may be represented as either the lower case () or the upper case (?) of “omega” (which is Greek for “last”). Technically “omega-3” is “omega minus 3”. In the scientific literature omega-3 may be written as -3, ?-3 or n-3.13 The human body cannot make omega-3 fatty acids on its own so they must be obtained from food or supplements. Omega-3 fatty acids that are important in human function include: linolenic acid (18:3n-3; ALA), stearidonic acid (18:4n-3; SDA) eicosapentaenoic acid (20:5n-3; EPA), and docosahexaenoic acid (22:6n-3; DHA). In front of the n-3 designation, the number of carbons, and the number of double bonds are represented as C:D. As such, linolenic acid an omega-3 fatty acid with 18 carbons and 3 double bonds is designated at 18:3n-3. The conversion of linolenic acid (18:3n-3) to stearidonic acid (18:4n-3) is dependent on the enzyme such as delta-6-desaturase. If delta-6-desaturase function is inadequate, longer omega-3 fatty acids such as SDA, EPA & DHA must be provided in the diet. Since linolenic acid has many health benefits in and of itself, it should also be obtained from food or supplements even if SDA, EPA & DHA supplements are taken because of inadequate delta-6-desaturase function.14

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