What is Magnesium? Magnesium is the fourth most abundant mineral in the body and is essential to good health. Approximately 50% of total body magnesium is found in bone. The other half is found predominantly inside cells of body tissues and organs. Only 1% of magnesium is found in blood, but the body works very hard to keep blood levels of magnesium constant. How could Magnesium help my body? Magnesium helps to keep normal muscle and nerve function, in addition it helps steady your heart’s rhythm and supports a healthy immune system.