My seven year old has had cradle cap on and off for seven years and although coconut oil worked temporarily, it kept returning. Although the cradle cap disappeared after a week on six drops of evening primrose oil with her fish oil, time will tell if she is cured. But, research from Sweden indicates that cradle cap may be caused by an insufficient supply of an essential fatty acid called Gamma-linolenic acid (GLA.) According to easybabylife.com
According to the University of Maryland Medical Center, it looks like you need a functioning Delta-6-Desaturase enzyme system to convert linoleic acid into GLA. Babies sometimes have an immature D6D systems and end up being deficient in GLA. But GLA and evening primrose oil should be used under the supervision of a healthcare provider because there have been reports of Omega 6 supplements inducing seizures (along with fluorescent lights and playing a Wii!) So consult a nutritionist or a holistic pediatrician (or your favorite biochemist!) before beginning supplementation for cradle cap. Also, Aubrey sells an evening primrose oil that can be used topically."GLA is required for the formation and maintenance of healthy skin cells. The hypothesis is that the infants' have an immature enzyme system and are therefore unable to produce sufficient GLA on their own, thus giving rise to the symptoms."