About calcium supplements, the blood needs a carefully adjusted amount of sodium, potassium, magnesium
and calcium (
and a few other minerals) in order for the cells to
function and create movement. An example is why you get thirsty after eating a high-salt meal (rich in sodium). The body needs more water to thin out the concentration of sodium.
We carry almost 1 kg (= 2+ pounds) of calcium in the bones, but the concentration of calcium in the blood is very low (approx. 10 mg pr dl.