The Uselessness of Nitrogen in the Atmosphere

My 165-pound body consists of about 110 pounds of oxygen, 30 pounds of carbon, 16 pounds of hydrogen, 6 pounds of nitrogen, and 3 pounds of everything else. Basic stuff, mostly, the stuff of water and air. You'd think we could get almost everything we need to build our bodies by taking deep breaths and gulps of water. But it's not quite that simple. Consider those 6 pounds of nitrogen in my body. Our cells build proteins by stringing together chemical units called amino acids, and every amino...