Individual amino acid requirements in humans: an update

Abstract

To discuss recent amino acid requirement studies in adult humans and school-age children, primarily determined using the indicator amino acid oxidation technique. 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. 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.