Chris- the nitty gritty indeed. just testing 25D is only getting a fraction of the true picture of what is happening with vitamin d. people have seized on this measure because there is a correlation between low levels and disease... the funny is, we all know how flawed correlational studies are. these studies are not bothering to look at why vit d levels are low. the studies that really crack me up are the studies that find low 25D levels in people living in India and Africa. studies conclude this results from "dark skin". come on, wake up. these people developed their skin specific to that environment... nature knows best, right? the studies are flawed. they draw a cause and effect conclusion where none exists. but you don't have to take my word for it people, get tested and figure it out yourself. like me, you will be throwing your vitamin d in the trash.