NUTRITION DURING PREGNANCY, LACTATION, INFANCY, AND CHILDHOOD
Location: Children Nutrition Research Center (Houston, Tx)
Title: Protein and amino acid metabolism and requirements
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: November 1, 2005
Publication Date: May 1, 2006
Citation: Heird, W.C., Kashyap, S. 2006. Protein and amino acid metabolism and requirements. In: Polin, R.A., Fox, W.W., Abman, S.H., editors. Fetal and Neonatal Physiology. 3rd edition. Philadelphia, PA: W.B. Sanders. p. 527-539.
Proteins are the major structural and functional components of all cells of the body. Enzymes, membrane carriers, blood transport molecules, intracellular matrix, and even hair and fingernails are proteins, as are many hormones. Proteins also constitute a major portion of all membranes, and the constituent amino acids of protein act as precursors of many coenzymes, hormones, nucleic acids, and other essential molecules. An adequate supply of dietary protein is therefore necessary to ensure cellular integrity and function. In this chapter, some general aspects of the chemistry and metabolism of proteins and amino acids are reviewed. This is followed by discussions of the protein and, then, amino acid needs of preterm, low birth weight (LBW) infants. Finally, the physiologic, pathologic, and environmental factors that affect protein and amino acid needs are discussed, and an attempt is made to reach conclusions concerning the preterm LBW infant's needs for protein and amino acids. Nitrogen, the characteristic element of protein, makes up about 16% of its weight. Thus, nitrogen metabolism is often considered to be synonymous with protein metabolism.