Original Contribution | Published:

Functional GI Disorders

Acute Tryptophan Depletion Alters Gastrointestinal and Anxiety Symptoms in Irritable Bowel Syndrome

The American Journal of Gastroenterology volume 101, pages 25822587 (2006) | Download Citation

Subjects

Abstract

OBJECTIVES:

To assess the effect of acute changes in serotonin (5-HT) synthesis using the acute tryptophan depletion (ATD) paradigm on gastrointestinal (GI) and mood symptoms in irritable bowel syndrome (IBS).

METHODS:

In a randomized double-blind crossover study, 29 subjects (18 patients with ROME II defined IBS and 11 age-matched controls) were studied under ATD and acute tryptophan increase (ATI) conditions. GI symptoms, mood and anxiety ratings, as well as plasma tryptophan concentrations were measured.

RESULTS:

Total (and free) plasma tryptophan concentrations decreased on the ATD day in patients (73% [82%]) and controls (73% [80%]), and increased on the ATI day in patients (59% [143%]) and controls (61% [381%]). Compared with the ATD day, IBS patients reported more GI symptoms on the ATI day at +210 (p < 0.001) and at +270 (p < 0.05) min post drink. IBS patients also reported less anxiety on the ATI day compared with the ATD day at +270 min (p < 0.001). ATD and ATI did not affect these ratings in control participants. IBS patients had a lower mood compared with controls (p < 0.05), but this did not differ between the ATI and ATD days in either group.

CONCLUSIONS:

IBS patients' GI and anxiety responses to changes in tryptophan load differ from controls. This suggests a difference in serotonergic functioning between these two groups and provides evidence to support the hypothesis that 5-HT dysfunction is involved in IBS.

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Acknowledgements

This study was funded by Avon and Wiltshire Partnership NHS Trust R and D. The sponsors had no role in study design, data collection, data analysis, data interpretation, or writing of the report. M Franklin performed the tryptophan assays. Thank you to C Rogers for statistical advice and A Rich for her help in completion of the study.

Author information

Affiliations

  1. Clinical Science at South Bristol, University of Bristol, Bristol, United Kingdom

    • Jonathan Shufflebotham
    •  & Chris Probert
  2. School of Psychiatry & Clinical Neurosciences, University of Western Australia, Perth, Australia

    • Sean Hood
  3. Bristol Royal Infirmary, Bristol, United Kingdom

    • Julie Hendry
  4. Psychopharmacology Unit, University of Bristol, Bristol, United Kingdom

    • Dana A Hince
    • , Kelly Morris
    • , David Nutt
    •  & John Potokar

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Correspondence to John Potokar.

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DOI

https://doi.org/10.1111/j.1572-0241.2006.00811.x

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