Do some googling on Hollick of Boston who has done considerable work on Vitamin D and has many case studies online. Here is a lecture by him.http://www.youtube.com/watch?v=Cq1t9WqOD-0&feature=channel
May I suggest you look up a Boston Doctor named Hollick - he has countless articles online and also some usperb lectures on Youtube.He is not into this to make money but to help people and he has...