Docosahexaenoic acid (DHA) is an omega-3 fatty acid. In chemical structure, DHA is a carboxylic acid with a 22-carbon chain and six cis double bonds; the first double bond is located at the third carbon from the omega end. Its trivial name is cervonic acid, its systematic name is all-cis-docosa-4,7,10,13,16,19-hexa-enoic acid, and its shorthand name is 22:6(n-3) in the nomenclature of fatty acids.
Cold-water oceanic fish oils are rich in DHA. Most of the DHA in fish and complex organisms with access to cold-water oceanic foods originates in photosynthetic and heterotrophic microalgae, and becomes increasingly concentrated in organisms, as they move up the food chain. DHA is also commercially manufactured from microalgae; Crypthecodinium cohnii and another of the genus Schizochytrium.
Although Î±-linolenic acid (ALA) does convert to DHA, the process is inefficient and very limited even in healthy individuals. DHA is a major fatty acid in sperm and brain phospholipids and in the retina.
Dietary DHA may reduce the risk of heart disease by reducing the level of blood triglycerides in humans. Low levels of DHA have been associated with Alzheimer's disease.