A quick google search found this: http://www.google.com/search?q=%223-6+times%22+%22vitamin+d%22+AND+melanin&ie=UTF-8&oe=UTF-8&hl=en&client=safari http://www.g

A quick google search found this: http://www.google.com/search?q=%223-6+times%22+%22vitamin+d%22+AND+melanin&ie=UTF-8&oe=UTF-8&hl=en&client=safari http://www.google.com/search?q=%223-6+times%22+%22vitamin+d%... My battery is about to die in the iPhone, so I don't have time to curate the list, but from a quick glance a couple of the sources from the google search look credible.