[nicoburns]

I agree that the recommended dose is probably too low, but part of the reason for the discrepancy may be poor absorption of many supplements. I ended up with side effects (racing heart and thirst that wouldn't go away - which reliably went away when I backed down the dose and came back when I upped it again) from only 2000IU/day (as an adult). But I was taking it in the form of drops under the tongue (and as a combined formulation of D3 and K2) which I suspect is absorbed much better than the typical pills which are swallowed.