This up-to-date book presents basic concepts and recent advances in amino acid biochemistry and nutrition, providing comprehensive coverage of developments over the past 45 years. It includes information on absorption, metabolism, and excretion of amino acids while addressing protein quality and requirements. The text discusses metabolic pathways of amino acids in relation to health and disease in various organisms, as well as species differences in metabolism of amino acids. The author also presents a critical analysis of amino acid supplementation to humans and animals.