Magnesium is a mineral found in the body that helps to maintain proper muscle and nerve function. Approximately 50% of the body's magnesium is stored in bone with the rest stored in body tissues or blood. The body maintains a steady state of about 1% magnesium in blood. There are approximately 25g of magnesium in the body, and the mineral is responsible for more than 300 chemical reactions. Magnesium is found in green leafy vegetables, legumes, nuts, seeds, and whole grains.