I would read about magnesium. I read this website yesterday. This link contains the osteoporosis section in relation to magnesium- http://www.mgwater.com/listd.shtml#osteo
This was the website that first grabbed my attention on magnesium- http://www.newtreatments.org/Hypomagnesia/ga/203 If you look at the sources for magnesium, it is evident on the surface that the country as a whole is not getting enough magnesium. There is a relationship between calcium and magnesium. This link says that magnesium taurate is the best source of magnesium and that some forms are downright dangerous. Here are the Google results for "magnesium taurate"- http://tinyurl.com/95tnq