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Ī 2007 study suggested that Dietary supplementation with omega−3 fatty acids did not appear to affect the risk of cancer or heart disease. In foods exposed to air, unsaturated fatty acids are vulnerable to oxidation and rancidity.
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The ability to make the longer-chain omega−3 fatty acids from ALA may be impaired in aging. 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). 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). Mammals are unable to synthesize the essential omega−3 fatty acid ALA and can only obtain it through diet. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds, while sources of EPA and DHA include fish and fish oils. Marine algae and phytoplankton are primary sources of omega−3 fatty acids (which also accumulate in fish). 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. 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.
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Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or n−3 fatty acids, 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.
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