title: Dietary tryptophan intake and suicide rate in industrialized nations.
abstract: BACKGROUND
  The objective of this study was to assess the ecological association of dietary tryptophan intake and suicide rates across industrialized nations. Tryptophan, an essential amino acid, is the rate-limiting precursor of serotonin biosynthesis. The serotonergic system has been strongly implicated in the neurobiology of suicide.
  
  
  METHODS
  Contemporary male and female suicide rates for the general population (42 countries) and the elderly (38 countries) were correlated with national estimates of dietary tryptophan intake.
  
  
  RESULTS
  Measures of tryptophan intake were significantly negatively associated to national suicide rates. Controlling for national affluence, total alcohol consumption and happiness levels slightly attenuated these associations, but left all of them negative.
  
  
  CONCLUSIONS
  The effect is an ecological (group-level) finding. Estimated per capita tryptophan supply is only a proxy for actual consumption.
  
  
  CONCLUSIONS
  Developed nations ranking high in dietary tryptophan intake rank low in suicide rates, independent of national wealth, alcohol intake and happiness.
authors.affiliation: Department of Basic Psychological Research, School of Psychology, University of Vienna, Austria. martin.voracek@univie.ac.at
authors.forename: Martin
authors.initials: M
authors.lastname: Voracek
authors.forename: Ulrich S
authors.initials: US
authors.lastname: Tran
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D001208:Asia / Q000453:epidemiology; D001315:Australia / Q000453:epidemiology; D019049:Developed Countries / Q000706:statistics & numerical data*; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D005060:Europe / Q000453:epidemiology; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017678:Sex Distribution; D013405:Suicide / Q000706:statistics & numerical data*; D014364:Tryptophan / Q000008:administration & dosage* / Q000097:blood; D014481:United States / Q000453:epidemiology
chemical_list: D014364:Tryptophan