Magnesium is the second most abundant nutrient in the body and is thought to be responsible for over 300 different processes. One of the primary functions of magnesium is healthy muscle function and contraction, including the vital muscles in the heart. Magnesium also plays an essential role in the maintenance of healthy bones. Between 50% to 60% of the body's magnesium is actually stored in the bones, where it works in combination with calcium to increase bone density and strengthen bones and teeth. Calcium is one of the most abundant and vital minerals in the body. It is thought that nearly 99% of the body's calcium is stored in the bones and teeth, whilst the remaining 1% circulates in the blood. When blood calcium levels are low, the body robs calcium from the bones. Over time, this can cause bones to become porous and weak. Maintaining healthy calcium levels can help to strengthen bones and support muscle function. Calcium also plays a role in the production of digestive enzymes that can help to neutralise stomach acids and may reduce heartburn.