Protein requirements in healthy school‐age children determined by using the indicator amino acid oxidation technique

Abstract

Protein (PRO) requirements in school‐age children were determined by the indicator amino acid oxidation (IAAO) method. Four, healthy children (8 – 11 yr) each randomly received a minimum of three PRO intakes below 0.9 and three intakes above 0.9 g/kg/d; range = 0.16 – 1.84 g/kg/d. The diets were isocaloric and provided energy at 1.7 X REE. PRO was given as an amino acid mixture based on egg protein composition, except phenylalanine which was maintained constant across intakes. PRO requirements were determined by measuring the oxidation of L‐[1‐13C]‐phenylalanine to 13CO2 (F13CO2). Breath and urine samples were collected at baseline and isotopic steady state. Linear regression crossover analysis identified a breakpoint (requirement) at minimal F13CO2 in response to different PRO intakes.Preliminary results indicate the mean and population‐safe PRO requirements to be 1.35 and 1.59 g/kg/d, respectively. These results are significantly higher than the mean and population‐safe PRO requirements of 0.76 and 0.95 g/kg/d, respectively, currently recommended by the Dietary Reference Intakes (DRI 2005) for macronutrients This study is the first to directly estimate protein requirements in children and suggests that the current recommendations, based on a factorial method are severely underestimated. (CIHR supported)