A theoretical basis for increasing current estimates of the amino acid requirements in adult man, with experimental support

Abstract

Estimates of the minimum (obligatory) rates of loss of indispensable acids via irreversible oxidation in healthy young adults are predicted from published data for obligatory nitrogen losses and from published values for whole-body protein turnover and the efficiency of amino acid recycling. The estimates obtained by these two different approaches are consistent and equal to or in most cases considerably higher than current values for the upper range of the individual amino acid requirements in healthy adults. From these estimates of the obligatory, or minimum, rates of amino acid oxidation, the minimum requirements for indispensable amino acids are predicted. These are about two to three times higher than current requirement figures. Experimental support for these higher requirement figures is presented, based on published 13C-labeled amino acid tracer studies. When these revised estimates are expressed per unit of protein need, the amino acid pattern is similar to the 1985 Food and Agriculture Organization/World Health Organization/United Nations University amino acid scoring pattern for the preschool child (aged 2–5 y).