Collagen is a protein that forms the structural component of connective tissues, such as tendons, ligaments, bones and joints. Contains 19 amino acids, including eight essential amino acids: isoleucine, leucine, lysine, methionine, phenylalanine, threonine and valine. Since the body cannot produce these amino acids, we need protein sources – such as poultry, eggs, dairy, soy, quinoa and buckwheat – which are considered “complete” proteins because they contain all nine essential amino acids.