Listen to Dr Bruce Hollis on www.UCTV.tv , "Vitamin D and the prostate gland" at 19 min into the lecture. You have a free hand in conjunction with skeletal health as half life for 25(oh)D is given to be 3 weeks. Non-skeletal benefits come from Vitamin D (cholecalciferol) acting directly on the breast, prostate, colon, brain and all other tissues with a half life of 24 hours. I understand Vitamin D MUST be taken daily for maximum benefit. There is no assay for cholecalciferol in bloodstream (yet) .