title: Prebiotic intake reduces the waking cortisol response and alters emotional bias in healthy volunteers.
abstract: BACKGROUND
  There is now compelling evidence for a link between enteric microbiota and brain function. The ingestion of probiotics modulates the processing of information that is strongly linked to anxiety and depression, and influences the neuroendocrine stress response. We have recently demonstrated that prebiotics (soluble fibres that augment the growth of indigenous microbiota) have significant neurobiological effects in rats, but their action in humans has not been reported.
  
  
  OBJECTIVE
  The present study explored the effects of two prebiotics on the secretion of the stress hormone, cortisol and emotional processing in healthy volunteers.
  
  
  METHODS
  Forty-five healthy volunteers received one of two prebiotics (fructooligosaccharides, FOS, or Bimuno®-galactooligosaccharides, B-GOS) or a placebo (maltodextrin) daily for 3 weeks. The salivary cortisol awakening response was sampled before and after prebiotic/placebo administration. On the final day of treatment, participants completed a computerised task battery assessing the processing of emotionally salient information.
  
  
  RESULTS
  The salivary cortisol awakening response was significantly lower after B-GOS intake compared with placebo. Participants also showed decreased attentional vigilance to negative versus positive information in a dot-probe task after B-GOS compared to placebo intake. No effects were found after the administration of FOS.
  
  
  CONCLUSIONS
  The suppression of the neuroendocrine stress response and the increase in the processing of positive versus negative attentional vigilance in subjects supplemented with B-GOS are consistent with previous findings of endocrine and anxiolytic effects of microbiota proliferation. Further studies are therefore needed to test the utility of B-GOS supplementation in the treatment of stress-related disorders.
authors.affiliation: Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, OX3 7JX, UK.
authors.forename: Kristin
authors.initials: K
authors.lastname: Schmidt
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Cowen
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Harmer
authors.forename: George
authors.initials: G
authors.lastname: Tzortzis
authors.forename: Steven
authors.initials: S
authors.lastname: Errington
authors.forename: Philip W J
authors.initials: PW
authors.lastname: Burnet
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D019587:Dietary Supplements; D004311:Double-Blind Method; D004644:Emotions / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009844:Oligosaccharides / Q000008:administration & dosage; D010775:Photic Stimulation / Q000379:methods; D056692:Prebiotics / Q000008:administration & dosage*; D051381:Rats; D012463:Saliva / Q000378:metabolism; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
chemical_list: D009844:Oligosaccharides; D056692:Prebiotics; C116580:fructooligosaccharide; D006854:Hydrocortisone