There's a new discussion paper out on vitamin D which deserves serious reading:
Vitamin D discovery outpaces FDA decision making
Some of it is very interesting if you want an opinion that suggests vitamin D supplementation, at any level, is bad and that low levels of 25 OH D3 are a product of disease, not a contributor. And as such are a marker of good things happening in the immune system. He includes the changes in gut flora as a source of obesity as being triggered by D2 supplementation (not had time to read all of this in detail) and I'm not sure I agree with him on what's happening (anywhere!), but there's plenty there to think about here. You have to look at both sides of a decision making process.
No time to read it in detail today, arghhhh
EDIT later in the day
By the time you've been through enough of the easily available references to realise that they don't actually say what the author claims they say, you tend to bin the review. There's the bin, dump goes the review. Gimme the D3.