Vitamin D, the new ‘It Girl’ of the supplement industry, has been widely reported to do all sorts of miraculous things despite the lack of reliable scientific evidence. The number of blood tests for vitamin D levels among people 65 and older, increased 83-fold from 2000 to 2010, according to the Centers for Disease Control and Prevention. Labs performing these tests are reporting perfectly normal levels of vitamin D — 20 to 30 ng/mL of blood as “insufficient” (randomized tria