I no longer consider the Inst. of Medicine a scientifically credible organization. That last D report just boiled my blood with self-interests, incompetence and thinly covered corruptions that further delay recognizable progress where a lot of known research has been unfinished, and largely unstarted, for 50-60 yrs. About all I can say nice is that it made 4000 iu caps slightly better protected legally if one of the anti-DSHEA laws ever passed; the report also recognized (wrong) blood levels as an alternative basis of discussion for daily augmentation rather than just RDA (remember 200-400 iu of D2 as a basis of adequate nutrition or "quackery" discussions?).
This VitaminDWiki advocacy site looks useful to me.