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Moderate whisky consumption in combination with an evening meal reduces tryptophan availability to the brain but does not influence performance in healthy volunteers

Author: Markus, C.R. · Sierksma, A. · Verbeek, C. · Rooijen, J.J.M. van · Patel, H.J. · Brand, A.N. · Hendriks, H.F.J.
Institution: TNO Voeding
Source:British Journal of Nutrition, 6, 92, 995-1000
Identifier: 238105
doi: doi:10.1079/BJN20041287
Keywords: Health · Analytical research · 5-hydroxytryptamine · Alcohol · Cognition · Information processing · Mood · alcohol · amino acid · glucose · insulin · tryptophan · water · adult · aged · alcohol consumption · amino acid blood level · amino acid transport · article · blood sampling · controlled study · glucose blood level · human · human experiment · insulin blood level · male · meal · mood · night · normal human · response time · statistical significance · task performance · time · tryptophan brain level · volunteer · whiskey · Affect · Aged · Alcohol Drinking · Amino Acids · Analysis of Variance · Biological Availability · Blood Glucose · Brain · Choice Behavior · Cognition · Eating · Ethanol · Humans · Insulin · Male · Middle Aged · Reaction Time · Serotonin · Tryptophan


Brain serotonin (5-HT) synthesis is controlled by nutrients that influence the availability of plasma tryptophan (Trp) as compared with the sum of the other large neutral amino acids (LNAA; Trp:LNAA). Alcohol consumption is found to change mood and performance and this might well be due to alterations in the plasma Trp:LNAA ratio and brain 5-HT. In the present study, we tested whether whisky consumption as part of a meal may alter the plasma Trp:LNAA ratio and influence mood and performance in healthy volunteers. Twenty-four healthy male subjects participated in a within-subjects cross-over study. Subjects consumed whisky (125 ml; 40 g alcohol) or water (125 ml) as part of a standard evening meal. Effects of whisky consumption were tested on mood and choice reaction time and blood samples were taken to measure changes in plasma amino acids, glucose and insulin. The plasma Trp:LNAA ratio showed a significant decline 2h after whisky consumption of alcohol (P<0.001). No effects were found on choice reaction time or mood as compared with the control condition. The present findings reveal that whisky consumption alters available plasma Trp for uptake into the brain, whereas there were no effects on mood and performance. © The Authors 2004.