Dietary element
Dietary elements are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen present in common organic molecules. The term "dietary mineral" is archaic, as the substances it refers are chemical elements rather than actual minerals. Chemical elements in order of abundance in the human body include the seven major dietary elements calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium. Important "trace" or minor dietary elements, necessary for mammalian life, include iron, cobalt, copper, zinc, molybdenum, iodine, bromine, and selenium. Over twenty dietary elements are necessary for mammals, and several more for various other types of life. The total number of chemical elements that are absolutely needed is not known for any organism. Ultratrace amounts of some elements are known to clearly have a role but the exact biochemical nature is unknown, and others are suspected to have a role in health, but without proof. Most chemical element that enter into the dietary physiology of organisms are in the form of simple compounds.