Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/1/2007
Publication Date: 1/1/2008
Citation: Roth, R.M., Castillo, L. 2008. Macronutrient requirement for growth: Protein/amino acid. In: Duggan, C., Watkins, J.B., Walker, W.A., editors. Nutrition In Pediatrics. 4th edition. Hamilton, Ontario:BC Decker Inc. p. 49-58.
Technical Abstract: Current recommendations by the Institute of Medicine on amino acid requirements in healthy children older than 6 months and for children and adolescents have been established using the factorial approach, which takes into account: i) maintenance for obligatory losses, which is estimated by regression analysis of the relationship between nitrogen intake and nitrogen balance, ii) measurement of the rates of protein deposition, which are derived from body composition analysis, and iii) estimates of the efficiency of protein utilization, which are derived from the slope of the line relating intake and balance. Under this concept, the need for total protein and/or a particular amino acid for growth is equal to the rate of protein deposition and/or the content of that particular amino acid to the protein being deposited. However, a problem with this approach is that the relation between protein intake and nitrogen retention is not linear, thus the efficiency of nitrogen retention is less as zero balance is approached. In addition due to the lack of pediatric data, estimates of variation are obtained from the adult population. Although this is the best data available to date, studies in children using carbon oxidation techniques are being published and will help to better define amino acid requirements for nutritional balance in healthy children. There is also a great need for defining functional amino acid requirements in this population.