The Prescriber’s Letter, March, 2008 issue, affirms what has been suspected for many years. You should not take the usually recommended high doses of calcium to treat or prevent osteoporosis and fractures without balancing with Magnesium. Some of that calcium goes into the plaque in the coronary arteries. If you take 1000mg of calcium a day, you should take at least 500mg of Magnesium. Don’t forget your high-dose vitamin D3 (5000units) as well.
Prescriber's Letter (subscription required), March 2008.