DHA is an omega-3 fatty acid, chemically it is a carboxylic acid with a 22-carbon chain and six cis double bonds. Its chemical formula is C22H32O2 and Mol. Mass is 328.488 g/mol. Fish oils are the primary source of DHA. Research is being done on its application in treatment of Alzheimer's disease. It is also used as a supplement by pregnant women because studies indicate that low levels of erythrocyte DHA are associated with poor retinal development, low visual acuity, and poor cognitive development. DHA is becoming popular as a supplement for infants because it promotes healthy brain development and makes infants gain weight faster.