There can be serious health risks if you supplement with too much calcium. This can cause a blood condition called hypercalcemia that can harm your kidneys. If you take too much calcium, your body might not be able to absorb other minerals that you need. Most of the time, however, hypercalcemia is due to thyroid problems. The US Office of Dietary Supplements recommends that women take no more than 2,500 mg of calcium a day.