Regarding calcium, I'd recommend anyone concerned to use Google and research Vitamins D3 and K2. It's generally considered that most people who do not work outside are deficient in D3. There are various home test kits available which involve a skin prick and blood spots being sent off to a lab.
While it's possible to overdose on Vit D3 (hence the advisability of a blood test) it is not considered possible to o.d. on Vit K2.
The interaction, as I understand it simplistically, is that D3 makes the calcium available in your bloodstream and K2 directs it to where it belongs.
http://articles.mercola.com/sites/articles/archive/2011/03/26/the-delicate-dance-between-vitamins-d-and-k.aspx
http://articles.mercola.com/sites/articles/archive/2013/10/19/vitamin-d-vitamin-k2.aspx
B.