Are intravenous amino acid solutions unbalanced?

It is clear that amino acid-based nutritional support beneficially affects nitrogen balance. Less clear is the optimal composition of amino acids for nutritional support of the catabolic patient. We have addressed the optimal composition and proportions of amino acids for support of the critically ill, catabolic patient. We discuss the concept of conditionally indispensable amino acids and review the requirements for histidine, serine, arginine, taurine, cysteine, tyrosine, and glutamine. The use of dipeptides for parenteral support of critically ill patients is reviewed and proposed changes in amino acid content for the catabolic patient are advanced.