Magnesium, along with calcium and potassium, is one of the major mineral elements needed by the body to stay healthy. It is an essential constituent of all cells, being present in the bones and teeth and helps to maintain normal nerve and muscle functions as well as a regular heartbeat. With a varied and balanced diet deficiency is rare as dietary magnesium is widespread in everyday foods including dark green vegetables, fish, meat, rice and dairy products. However, should a supplement be necessary, it is advised to avoid an excess intake as it could cause harm.