What is "docosahexaenoic acid"

n. (context biochemistry English) An essential fatty acid 22-carbon atom omega-3 fatty acid with six ''cis'' double bonds, found in fish oils, metabolized to form the docosanoids.

n. an omega-3 fatty acid with 22 carbon atoms; found in fish (especially tuna and bluefish)

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, sperm, testicles and retina. It can be synthesized from alpha-linolenic acid or obtained directly from maternal milk (breast milk), fish oil or algae oil. DHA's structure is a carboxylic acid (-oic acid) with a 22- carbon chain (docosa- is Greek for 22) and six (hexa-) cis double bonds (-en-); with the first double bond 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 multi-cellular organisms with access to cold-water oceanic foods originates from photosynthetic and heterotrophic microalgae, and becomes increasingly concentrated in organisms the further they are up the food chain. DHA is also commercially manufactured from microalgae: Crypthecodinium cohnii and another of the genus Schizochytrium. DHA manufactured using microalgae is vegetarian.

Some animals with access to seafood make little DHA through metabolism, but obtain it in the diet. However, in strict herbivores, and carnivores that do not eat seafood, DHA is manufactured internally from α-linolenic acid, a shorter omega-3 fatty acid manufactured by plants (and also occurring in animal products as obtained from plants). Limited amounts of eicosapentaenoic and docosapentaenoic acids are possible products of α-linolenic acid metabolism in young women and men, and though DHA is difficult to detect above dietary background in males compared with females, this illustrates the importance of DHA production for the developing fetus and healthy breast milk. Rates of conversion are 15% higher for women, with those taking oral contraceptives demonstrating 10% higher DHA levels.

DHA is a major fatty acid in sperm, brain phospholipids and the retina. While the potential roles of DHA in the mechanisms of Alzheimer's disease are under active research, studies of fish oil supplements, which contain DHA, have failed to support claims of preventing cardiovascular diseases.