omega-3 fatty acid, a fatty acid with a double bond located at the third carbon atom away from the omega (methyl) end of the molecule. Major sources are cold-water fish and vegetable oils. Omega-3 fatty acids, such as eicosapentaenoic acid and docosahexaenoic acid, appear to have protective functions in preventing the formation of blood clots and reducing the risk of coronary heart disease. See also essential fatty acid.
