People can usually meet their calcium requirements with a healthy, traditional diet. Sometimes another 500-600mg is helpful. However, what is detrimental to health is too much calcium, especially calcium supplementation that is not in a 2 to 1 ratio with magnesium. For example, if you take a multivitamin with 800mg of calcium it should also supply you with at least 400mg of magnesium. More magnesium than that is not a problem, and is sometimes beneficial, as most of us are deficient in this nutrient, but more calcium is not helpful.
Often people will be told by their doctors that they need to supplement with 1500-2000mg a day of calcium. Interestingly, there are no research studies where individuals supplemented with those levels of calcium and succeeded in reversing osteoporosis. Yet, this is a common medical recommendation. Overlooked in these recommendations are the other nutrients needed to build bones and prevent bone loss-including magnesium.