Magnesium helps in 0ver 300 enzymatic functions other key functions of the body. Without enough calcium you may experience tooth decay, muscle spasms, leg and back cramps, brittle bones, rickets, poor growth, osteoporosis, and depression. But if you are getting a lot of calcium and still have symptoms, maybe it is time for Calcium Magnesium. Deficiency of magnesium can result in not using the calcium you already have.