No abstract

Whole blood glutathione synthesis rates are decreased, by about 60%, in critically ill septic children receiving limited nutritional support. Plasma cysteine fluxes and concentration of cysteine were increased in the septic patients, suggesting a hypermetabolic state with increased protein breakdown. The mechanisms whereby GSH synthesis rates are decreased in these patients are probably multifactorial, presumably involving an inflammatory response in the presence of limited nutritional support. The role of nutritional modulation and the use of cysteine prodrugs in maintaining GSH concentration and synthesis remain to be established.

We review the current international recommendations concerning the protein (nitrogen) and amino acid requirements of healthy individuals, from infancy to the later years of adult life and describe the changes in the recommendations for protein that have been made, since those issued in 1985 by Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU), by the International Dietary Energy Consultative Group. The current international requirements for the specific indispensable amino acids are critiqued briefly, and the rationale and basis for the proposed Massachusetts Institute of Technology (MIT) amino acid requirement pattern are presented. The evidence is then summarized that supports its use in practical considerations of protein nutrition. It is suggested that this MIT amino acid requirement pattern provides the best current estimates of the minimum physiological requirements for the indispensable amino acids in children and adults. It is further concluded that it would be difficult to argue for the continued use of the amino acid requirement values proposed by FAO/WHO/UNU in 1985 in the planning and assessment of dietary protein intakes for population groups worldwide. The MIT amino acid requirement pattern supports and strengthens the relevance of dietary protein quality as an important factor in human protein and amino acid nutrition.