Docosahexaenoic acid (DHA), a major component of fish oils and seal oil , is the most important fatty acid in the brain and retina and makes up more than 30% of the structural lipid (fat) in neurons. There is ample evidence that a deficiency of DHA is associated with depression, attention deficit hyperactivity disorder, and dementia. Clinical studies have shown that an increased intake of DHA may benefit patients with dyslexia and Alzheimer's disease.