Lol, yes i defo burn the midnight oil frequently, been sleeping terribly of late.
I do know that calcium needs vit d to absorb properly, so sunlight = good

Apart from that i know things increase calcium requirements, like smoking, too much coffee.
Also, with osteoporosis weight bearing exercise is the most important thing for prevention, more so than calcium intake.
Ive read that about magnesium being more important too. I question the RDIs for calcium a little, looking at how much is in yoghurt for example, the consumption of dairy would have to be really high every day to get enough. Hmmm, makes me really wonder on what the human body really needs. Is that requirement more because people have diets too high in protein? I know high protein diets increase calcium needs as well, because excess protein must be excreted, but to do that the body needs to excrete calcium too, therefore increasing requirements. So if someones protein intake was triple what was needed on a daily basis its probs not too unreasonable to think that their calcium requirements might be as much as triple too.
Would certainly be an interesting thing to study, but who would fund it lol, and no doubt the dairy and meat industry would rally against it hahaha.