title: Mood, food, and cognition: role of tryptophan and serotonin.
abstract: OBJECTIVE
  Food is not only necessary as a metabolic fuel for the body, it becomes more and more evident that there exists an association between food and brain functions like mood and cognition. Tryptophan represents a key element for brain functioning, because of its role as a precursor for production of neurotransmitter serotonin (5-hydroxytryptamine). In clinical conditions, which involve chronic immune system activation or under cytokine therapy, lower tryptophan levels because of high catabolism of tryptophan as indicated by the kynurenine to tryptophan ratio are common and often associate with depressive mood.
  
  
  RESULTS
  Studies in the in vitro model of mitogen-stimulated peripheral blood mononuclear cells revealed that several phytocompounds, mainly antioxidants like polyphenols and vitamins, can interfere with inflammatory signaling cascades including tryptophan breakdown. If extrapolated to the in vivo situation, such compounds could increase blood and brain tryptophan availability for serotonin production. Although there is some in vivo evidence for the effect of such compounds, outcomes are hardly predictable and most likely depend on the individual's immunological state.
  
  
  CONCLUSIONS
  Not only a diet rich in tryptophan but also a diet rich in antioxidants can have a positive impact on mood and cognition. This could be of special relevance for individuals who present with low grade inflammation conditions.
authors.affiliation: aDivision of Medical Biochemistry bDivision of Biological Chemistry, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Strasser
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Gostner
authors.forename: Dietmar
authors.initials: D
authors.lastname: Fuchs
mesh_terms: D000339:Affect; D000975:Antioxidants / Q000494:pharmacology / Q000627:therapeutic use; D001921:Brain / Q000187:drug effects; D003071:Cognition; D003072:Cognition Disorders / Q000378:metabolism* / Q000517:prevention & control; D003863:Depression / Q000378:metabolism* / Q000517:prevention & control; D004032:Diet; D005247:Feeding Behavior; D006801:Humans; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism* / Q000627:therapeutic use
chemical_list: D000975:Antioxidants; D012701:Serotonin; D014364:Tryptophan