Appropriate amino acid mixtures for tryptophan depletion and tyrosine/phenylalanine depletion and the safety of long-term amino acid depletion in humans

摘要

In a recent review in this journal, Badawy (2013) discussed the appropriate composition of amino acid mixtures for acute tryptophan depletion (AID) and acute phenylalanine/tyrosine depletion (APTD) studies and suggested that glycomacropeptide (GMP), which contains no aromatic amino acids, may be a suitable protein to use in acute depletion studies and long-term ATD and APTD treatments of patients with mania and schizophrenia. The review raises a number of interesting issues but has aspects that are problematic. The review suggests that GMP may be an effective nutritional therapy for manic and psychotic disorders. However, the review does not raise the issue of whether a protein will necessarily be free of adverse effects. GMP lacks aromatic amino acids and, if given chronically, would cause the intake of amino acids to be imbalanced. As pointed out by Young (2008), the extensive animal literature on the effects of imbalanced amino acid diets indicates adverse effects including reductions in food intake, growth retardation, and the development of fatty liver.