THE SIGNIFICANCE OF TRYPTOPHAN IN HUMAN-NUTRITION

Aside from its role as one of the limiting essential amino acids in pr otein metabolism, tryptophan (TRP) serves as precursor for the synthes is of the neurotransmitters serotonin and tryptamine as well as for th e synthesis of the antipellagra vitamin nicotinic acid and the epiphys eal hormone melatonin. By involvement in so manifold pathways, TRP and its metabolites regulate neurobehavioral effects such as appetite, sl eeping-waking-rhythm and pain perception. TRP is the only amino acid w hich binds to serum albumin to a high degree. Its transport through ce ll membranes is competetively inhibited by large neutral amino acids ( NAA). The TRP/NAA ratio in plasma is essential for the TRP availabilit y and thus for the serotonin synthesis in the brain. Due to its high T RP-concentration, human milk protein provides optimal conditions for t he availability of the neurotransmitter serotonin. Low protein cow's m ilk-based infant formulas supplemented with alpha-lactalbumin - a whey protein fraction containing 5.8% TRP - present themselves as a new ge neration of formulas, with an amino acid pattern different from the cu rrently used protein mixtures of adapted formulas, resembling that of human milk to a much higher degree.