These are popular “health oils” because they are rich sources of the essential fatty acid GLA (gammalinolenic acid), a vital ingredient for making important hormones, such as prostaglandins. Black currant oil has two advantages over evening primrose oil: It is less expensive, and it is one of the few oils that contain omega-3 in addition to omega-6 fatty acids. While these oils have been touted as cure-alls for many ailments, scientific evaluation of these oils yields mixed results. And the fact that they are extracted by chemical processing may render these tonics less healthy than advertised. Critics of these oils claim that since the body produces its own GLA from essential fatty acids contained in many foods, GLA supplements are not necessary. Proponents of these oils claim that some people, especially aging persons, may be unable to convert dietary essential fatty acids to GLA. GLA-containing oils, as well as the essential fatty acid DHA, are popular ingredients of a flurry of brain-boosting nutrients collectively known as “targeted nutritional intervention” (TNI) and are being studied for use in children with Down Syndrome.