Submitted to: Proceedings of the Nutrition Society
Publication Type: Review Article
Publication Acceptance Date: May 24, 2005
Publication Date: August 20, 2005
Citation: Heird, W.C. 2005. Biochemical homeostasis and body growth are reliable end points in clinical nutrition trials. Proceedings of the Nutrition Society. 64:297-303. Technical Abstract: Studies of biochemical homeostasis and/or body growth have been included as outcome variables in most nutrition trials in paediatric patients. Moreover, these outcome variables have provided important insights into the nutrient requirements of infants and children, and continue to do so. Examples of the value of such studies in improving parenteral nutrition, in defining essential fatty acid metabolism and requirements of infants, and in defining the protein and energy needs of low-birth-weight infants are discussed. Data from such studies have helped to define the mechanism of metabolic acidosis and hyperamonaemia associated with the use of early crystalline amino acid mixture and, hence, how to prevent these disorders. Such studies have allowed the development of parenteral amino acid mixtures that circumvent grossly abnormal plasma concentrations of most amino acids and appear to be utilized more efficiently. These studies have also helped define micronutrient requirements, including requirements for several such nutrients that had not been previously recognized as essential (e.g., Cr, se, Mo, alpha-linolenic acid). Studies of body growth have been particularly valuable in defining the nutritional requirements of low-birth-weight infants. Finally, studies of metabolic homeostasis coupled with more sophisticated metabolic studies have provided considerable insight into the metabolism of the essential fatty acids, linoleic acid (18:2n-6), and alpha-linolenic acid (18:3n-3). Although such studies have not defined the amount of the longer-chain polyunsaturated fatty acid (PUFA) synthesized from each of these essential fatty acids, i.e., arachidonic acid (20:4n-6) and docosahexaenoic acid (22:6n-3), they have shown that the rates of conversion are extremely variable from infant to infant, suggesting a possible explanation of why some studies show developmental advantages from intake of these fatty acids while others do not.