@nycmusic - yes, it's tricky--especially if you want to monitor your own personal needs/levels. I take less D3 in the summer (perhaps every other day), more in the winter--depending on the blood lab results. My integrative dr prefers a higher reading for D3; the conventional drs like it in a bit more conservative range. It's certainly a challenge w/calcium, too. I want to be able to take it a couple times a day for absorption purposes. If it's combined w/D, then how does that work?

As you know, I gain a lot of info from Inspire.com forum too, in addition to my own research/reading. Their format is changing, so not sure I'm a fan of it--we'll see. However I have found favorites (like yourself), where I feel I can trust their research.

I have been taking Calcium Hydroxyapatite for bone health--at least for now!