title: Effects of acute treatment with a tryptophan-rich protein hydrolysate on plasma amino acids, mood and emotional functioning in older women.
abstract: BACKGROUND
  Effective functioning of the neurotransmitter serotonin is important for optimal cognitive and emotional function. Dietary supplements able to increase availability to the brain of the precursor amino acid, tryptophan (TRP), and thereby enhance serotonin synthesis, can have measurable impact on these psychological processes.
  
  
  OBJECTIVE
  This study involves a randomised controlled trial of a TRP-rich egg-white protein hydrolysate (DSM Nutritional Products Ltd., Switzerland) on plasma amino acids, cognition, mood and emotional processing in older women.
  
  
  METHODS
  Following a baseline test day without treatment, 60 healthy women aged 45-65 years received drinks containing either 2 or 4 g of TRP-rich protein hydrolysate product or 3.11 g casein hydrolysate as a control. One hour later, they undertook a 2-h battery of cognitive and emotional tests.
  
  
  RESULTS
  The TRP-rich protein hydrolysate produced the expected dose-dependent increase in the ratio of plasma TRP to competing large neutral amino acids. TRP-rich protein hydrolysate (2 g only) prevented both the decline in wellbeing and increase in fatigue seen over the test session in the control group. This treatment dose resulted in a significant shift in emotional processing towards positive words and reduced negative bias in assessing negative facial expressions. Effects on cognition were small and not statistically reliable and are not reported here. However, there was no evidence for any adverse effects.
  
  
  CONCLUSIONS
  Consumption of a low dose of TRP-rich protein hydrolysate may have beneficial effects on emotional function that could promote feelings of wellbeing, possibly conferring resistance to deterioration in mood in healthy subjects or depressive episodes.
authors.affiliation: Department of Psychology, Whitelands College, University of Roehampton, Holybourne Avenue, London, SW15 4JD, UK, l.gibson@roehampton.ac.uk.
authors.forename: E L
authors.initials: EL
authors.lastname: Gibson
authors.forename: K
authors.initials: K
authors.lastname: Vargas
authors.forename: E
authors.initials: E
authors.lastname: Hogan
authors.forename: A
authors.initials: A
authors.lastname: Holmes
authors.forename: P J
authors.initials: PJ
authors.lastname: Rogers
authors.forename: J
authors.initials: J
authors.lastname: Wittwer
authors.forename: J
authors.initials: J
authors.lastname: Kloek
authors.forename: R
authors.initials: R
authors.lastname: Goralczyk
authors.forename: M H
authors.initials: MH
authors.lastname: Mohajeri
mesh_terms: D000339:Affect / Q000187:drug effects*; D000368:Aged; D000596:Amino Acids / Q000097:blood*; D002364:Caseins; D003071:Cognition / Q000187:drug effects; D019587:Dietary Supplements; D004311:Double-Blind Method; D004644:Emotions / Q000187:drug effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009483:Neuropsychological Tests; D011492:Protein Hydrolysates / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism; D014364:Tryptophan / Q000097:blood
chemical_list: D000596:Amino Acids; D002364:Caseins; D011492:Protein Hydrolysates; D012701:Serotonin; C475729:casein hydrolysate; D014364:Tryptophan