Illustration showing docosahexaenoic acid (DHA, yellow) crossing the blood-brain barrier, the semi-permeable membrane between the blood-vessels and brain. DHA is an essential omega-3 fatty acid which is important in the development and maintenance of a healthy brain and nervous system. This model shows how DHA and other omega-3 fatty acids cross the blood-brain barrier through the lipid transporter Mfsd2a (blue/purple).