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Bioavailability of tryptophan from a single oral dose of a trytophan-enriched peptide mixture in healthy men

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Author: Brink, E.J. · Boelsma, E. · Steijns, J. · Hendriks, H.F.J.
Institution: TNO Voeding Centraal Instituut voor Voedingsonderzoek TNO
Source:Current Topics in Nutraceutical Research, 3, 2, 169-176
Identifier: 237923
Keywords: Biology Health · Physiological Sciences · Amino acids · Dietary supplements · Serotonergic activity · Tryptophan · 5 hydroxyindoleacetic acid · 6 hydroxymelatonin o sulfate · Alanine · Arginine · Aspartic acid · Cystine · Glucose · Glutamic acid · Histidine · Insulin · Isoleucine · Leucine · Lysine · Melatonin · Methionine · Phenylalanine · Prolactin · Proline · Protein hydrolysate · Serine · Serotonin · Threonine · Tryptophan · Valine · Adult · Amino acid blood level · Area under the curve · Blood analysis · Brain function · Chemical binding · Clinical trial · Controlled clinical trial · Controlled study · Crossover procedure · Double blind procedure · Drug bioavailability · Human · Human experiment · Insulin blood level · Male · Metabolic parameters · Normal human · Prolactin blood level · Randomized controlled trial · Review · Serotonin blood level · Serotonin brain level · Serotonin metabolism · Urinalysis · Urine level


The aim of the study was to investigate the bioavailability of tryptophan (Trp) from a Trp-enriched peptide mixture in healthy men. A second objective was to investigate the effect of this Trp-enriched protein hydrolysate on potential parameters of serotonergic activity. serum serotonim melatonin and prolactin and urinary 5-hydroxyindol-acetic acid and 6-sulfatoxymelatonin. Glucose and insulin were measured as the placebo consisted of orange juice with added glucose. The study was a randomised, double blind, placebo-controlled, four-way crossover trial in eight healthy male subjects. Treatments consisted of a single oral load of a Trp-enriched protein hydrolysate containing 500 mg L-Trp, 500 mg L-Trp plus addition of a mixture of amino acids having the same composition as in the hydrolysate, 500 mg L-Trp, and placebo. Before and after ingestion blood and urine were collected during a period of 4 hours. The Trp-enriched protein hydrolysate increased the plasma Trp/LNAA ratio by about 70% at 60 to 90 min after ingestion. AM three Trp treatments induced a comparable plasma Trp-response demonstrating that Trp is readily available for the body independent of whether it was peptide-bonded or in free amino acid form. None of the Trp treatments affected serum serotonim prolactin, melatonin and insulin concentrations, as well as urinary 5-hydroxyindol-acetic acid and 64-sulfatoxymelatonin concentrations during the 4-hour measurement period in the morning. Copyright © 2004 by New Century Health Publishers, LLC.