Docosahexaenoic acid is an essential omega-3 fatty acid that is the primary structural component of the nervous system, skin, testicles and retina. Among its functions are to modulate the carrier-mediated transport of glycine, taurine, and choline and its deficiency is linked with neural cell death and cognitive decline. It is reported to be a ligand for the retinoid X receptor (RXR) in mouse brain tissue.