Phosphorus is a mineral that makes up 1% of a person's total body weight. It is present in every cell of the body. Most of the phosphorus in the body is found in the bones and teeth. The main function of phosphorus is in the formation of bones and teeth. It plays an important role in how the body uses carbohydrates and fats. It is also needed for the body to make protein for the growth, maintenance, and repair of cells and tissues.