According to HowStuffWorks, nitrogen is important to humans and all other living organisms because it is an important component of amino acids. Humans use amino acids to build proteins that form the building blocks of many biological tissues.
While nitrogen is an important component of amino acids, most organisms on Earth, including humans, are unable to use free nitrogen. Instead, HowStuffWorks explains that the nitrogen must become “fixed,” meaning that it must first bond with another element. Bacteria and blue-green algae complete most nitrogen fixation in terrestrial and marine ecosystems. Plants then draw these nitrogen-laden compounds from the soil and use them to build their own proteins. When humans or other animals eat these plants, they derive their own nitrogen. When plants and animals die and begin the process of decaying, much of the nitrogen locked in their bodies is released into the atmosphere where it is absorbed by other organisms.
Fortunately, HowStuffWorks explains that nitrogen is plentiful on Earth. When not bound to other elements, nitrogen forms a colorless, tasteless, odorless gas. Nitrogen is the most abundant element in the atmosphere, representing nearly 78 percent of the atmospheric volume and 75 percent of the atmospheric weight. It is required by all living things to live and grow.