Calcium and Magnesium

Calcium
Calcium is the most abundant mineral in the human body. Over 99% of calcium is stored in the bones and teeth. Calcium is needed for blood vessel contraction and expansion, the secretion of hormones and enzymes, muscle contraction, and sending central nervous system messages. About half of all men and three quarters of all women do not get enough calcium, which is extremely detrimental to long-term physical health (source)

Magnesium:
Magnesium is an essential element in biological systems. Magnesium occurs typically as the Mg2+ ion. It is an essential mineral nutrient for life and is present in every cell type in every organism.

61% of the US population do not meet the US RDA for levels of magnesium (source)