Vitamin D3 is produced in the _____, converted to 25-hydroxyvitamin D and stored in the _____- until it is converted to its most active form, 1,25-dihydroxyvitamin D (calcitriol), in the _______-.
skin
liver
kidneys
Vitamin D acts as a significant co-factor to promote _________ function, reduce ________, reduce ________ and enhance _____- and plays a physiologic role in many cells and tissues, including the brain.