title: Melatonin regulation as a possible mechanism for probiotic (VSL#3) in irritable bowel syndrome: a randomized double-blinded placebo study.
abstract: BACKGROUND
  Probiotics have treatment efficacy in irritable bowel syndrome (IBS), but the exact mechanism remains obscure. One hypothesis is the mediation of melatonin levels, leading to changes in IBS symptoms.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the effects of a probiotic, VSL#3, on symptoms, psychological and sleep parameters, and pain sensitivity in IBS, and relate these parameters to in vivo melatonin levels.
  
  
  METHODS
  Forty-two IBS patients were randomly assigned to receive VSL#3 or placebo for 6 weeks. Subjects completed bowel and psychological questionnaires, underwent rectal sensitivity testing and saliva melatonin assays.
  
  
  RESULTS
  Abdominal pain duration and distension intensity decreased significantly in the probiotic group, along with an increase in rectal distension pain thresholds. A correlation between increase in pain tolerance and improvement in abdominal pain scores (r = 0.51, p = 0.02) was seen with probiotic. There was an increase in salivary morning melatonin levels in males treated with VSL#3, which correlated (r = 0.61) with improved satisfaction in bowel habits. When grouped based on baseline diurnal melatonin levels, patients with normal diurnal fluctuations showed an increase in morning melatonin levels with VSL#3 treatment, which significantly correlated with improved satisfaction in bowel habits (r = 0.68). They also had reduced symptom severity scores and abdominal pain duration when treated with VSL#3, as well as satisfaction with bowel movements and quality-of-life.
  
  
  CONCLUSIONS
  VSL#3 improved symptoms and increased rectal pain thresholds. Symptom improvement correlated with a rise in morning melatonin, significant in males and subjects with normal circadian rhythm. This suggests that probiotics may act by influencing melatonin production, hence modulating IBS symptoms, in individuals with a normal circadian rhythm.
authors.affiliation: Department of Gastroenterology and Hepatology, National University Health System, 1E Kent Ridge Road, NUHS Tower Block Level 10, Singapore, 119228, Singapore, reuben_wong@nuhs.edu.sg.
authors.forename: Reuben K
authors.initials: RK
authors.lastname: Wong
authors.forename: Cao
authors.initials: C
authors.lastname: Yang
authors.forename: Guang-Hui
authors.initials: GH
authors.lastname: Song
authors.forename: Jennie
authors.initials: J
authors.lastname: Wong
authors.forename: Khek-Yu
authors.initials: KY
authors.lastname: Ho
mesh_terms: D000328:Adult; D000368:Aged; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D008550:Melatonin / Q000096:biosynthesis / Q000502:physiology*; D008875:Middle Aged; D019936:Probiotics / Q000737:chemistry / Q000627:therapeutic use*; D012007:Rectum / Q000503:physiopathology; D012463:Saliva / Q000737:chemistry; D012684:Sensory Thresholds; D012890:Sleep / Q000502:physiology; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D008550:Melatonin
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