Magnesium (mag-NEE-zee-um) is one of the most abundant minerals in the soft tissues of humans. It helps convert carbohydrates, protein, and fats to energy and is involved in the manufacture of proteins. It also helps synthesize genetic material within cells and remove toxic substances from the body. Magnesium is important for muscle relaxation and contraction and nerve transmission. In addition, it helps prevent tooth decay, heart disease, and irregular heartbeat. The hormone that regulates blood calcium levels is dependent on magnesium to function normally. Magnesium is found in most foods, especially green, leafy vegetables. It's also one of the minerals that makes hard water 'hard.' A deficiency in magnesium may develop in conjunction with certain diseases and conditions, such as kidney disease, diabetes, disease of the thyroid gland, or even acute alcoholism. Symptoms of magnesium deficiency include depression, muscular weakness, severe dizziness, tremors, and convulsions. It's treated by injections with the chemical magnesium sulfate. Taking too much magnesium--typically from ingesting too many nonprescription antacids and laxatives containing the mineral--can lead to magnesium toxicity, which can be fatal.