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Omega-3 fatty acid

The meaning of «omega-3 fatty acid»

Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or n−3 fatty acids,[1] are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chemical structure.[2] They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology.[3][4] The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), found in plant oils, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both commonly found in oils of marine fish.[3] Marine algae and phytoplankton are primary sources of omega−3 fatty acids (which also accumulate in fish). Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds, while sources of EPA and DHA include fish and fish oils.[1]

Mammals are unable to synthesize the essential omega−3 fatty acid ALA and can only obtain it through diet. However, they can use ALA, when available, to form EPA and DHA, by creating additional double bonds along its carbon chain (desaturation) and extending it (elongation). Namely, ALA (18 carbons and 3 double bonds) is used to make EPA (20 carbons and 5 double bonds), which is then used to make DHA (22 carbons and 6 double bonds).[1][2] The ability to make the longer-chain omega−3 fatty acids from ALA may be impaired in aging.[5] In foods exposed to air, unsaturated fatty acids are vulnerable to oxidation and rancidity.[2][6]

A 2007 study suggested that Dietary supplementation with omega−3 fatty acids did not appear to affect the risk of cancer or heart disease.[7] Furthermore, fish oil supplement studies have failed to support claims of preventing heart attacks or strokes or any vascular disease outcomes.[8][9] However, a 2021 study concluded that just a 1% increase of Omega-3 acids in the blood led to a five year increase in lifespan. [10]

The terms ω–3 ("omega–3") fatty acid and n–3 fatty acid are derived from organic nomenclature.[2][11] One way in which an unsaturated fatty acid is named is determined by the location, in its carbon chain, of the double bond which is closest to the methyl end of the molecule.[11] In general terminology, n (or ω) represents the locant of the methyl end of the molecule, while the number n–x (or ω–x) refers to the locant of its nearest double bond. Thus, in omega–3 fatty acids in particular, there is a double bond located at the carbon numbered 3, starting from the methyl end of the fatty acid chain. This classification scheme is useful since most chemical changes occur at the carboxyl end of the molecule, while the methyl group and its nearest double bond are unchanged in most chemical or enzymatic reactions.

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