While 60% of magnesium in the body is found in the bones and teeth, 40% of the magnesium in the body is found in the muscles. In the muscles, magnesium is primarily responsible for muscle relaxation after contraction. Studies indicate that 68% of US adults consume less than the RDA of magnesium per day. A deficiency of magnesium in the body can result in a myriad of problems, including muscle cramps and nerve irritability.