Protein, amino acid metabolism and therapy: Edited by Erich RothIndividual amino acid requirements in humans: an updateElango, Rajavela,b; Ball, Ronald Ob,c; Pencharz, Paul Ba,b,cAuthor Information aThe Research Institute, The Hospital for Sick Children, Toronto, Canada bDepartment of Nutritional Sciences, University of Toronto, Ontario, Canada cDepartment of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada Correspondence to Paul B. Pencharz, Division of Gastroenterology, Hepatology and Nutrition, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8 Tel: +1 416 813-7733; fax: +1 416 813-4972; e-mail: firstname.lastname@example.org Current Opinion in Clinical Nutrition and Metabolic Care: January 2008 - Volume 11 - Issue 1 - p 34-39 doi: 10.1097/MCO.0b013e3282f2a5a4 Buy Metrics Abstract Purpose of review To discuss recent amino acid requirement studies in adult humans and school-age children, primarily determined using the indicator amino acid oxidation technique. Recent findings Using the minimally invasive indicator amino acid oxidation model, requirements for most indispensable amino acids have been defined in adult humans. The estimates are comparable to the values obtained using the more elaborate 24-h indicator amino acid oxidation and balance model. The less-invasive indicator amino acid oxidation model has also been successfully applied to define requirements in healthy school-age children and children with disease. A recent adaptation of the indicator amino acid oxidation method to determine protein requirements in adult humans resulted in mean and safe values of 0.93 and 1.2 g protein/kg/day, respectively. These estimates are 40–50% higher than current recommendations and suggest an urgent need to reassess recommendations for protein intake in humans. Summary In summary, indicator amino acid oxidation is a robust technique, and has resulted in the definition of amino acid and protein requirements in adult humans and children. A wider application of the technique in other vulnerable populations across life stages and in other diseases is now possible. © 2008 Lippincott Williams & Wilkins, Inc.