99% of the mass of the human body is made up of only six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Every organic molecule contains carbon. Since 65-90% of each body cell consists of water (by weight), it isn't surprising that oxygen and hydrogen are major components of the body. Here's is a look at the major elements in the body and what these elements do. Carbon Carbon is found in every organic molecule in the body. Photograph of graphite, one of the forms of elemental carbon. U.S. Geological Survey Carbon is ingested in food that is eaten and breathed in as a component of air. It is found in the lungs as a waste product of respiration, carbon dioxide.
