Contact

Professor Julian Walters
julian.walters@imperial.ac.uk 

What we do

Professor Julian Walters has conducted national and international leading research for over 20 years on clinical, translational and basic topics to advance the understanding of bile acids and their contribution to gastro-intestinal symptoms including urgency, bowel frequency and changes in stool type.

Why it is important

Bile Acid Diarrhoea (BAD) is an overlooked and under-appreciated cause of chronic bowel disease.  Our publications have shown that BAD accounts for up to a third of patients who have been diagnosed with diarrhoea-predominant IBS. This produces a population prevalence of around 1%, and additionally there are many people with inflammatory bowel disease or previous surgery who have this.

How it can benefit patients

Increased awareness and improved diagnosis, linked to a better understanding of treatment and new pathways, will aid patients who are often misdiagnosed with multiple unmet needs.

Summary of current research

Investigation of the pathophysiology of BAD as determined by overproduction of bile acids, including genetic variants in liver enzymes and impaired feedback inhibition by FGF19.  Improvements in diagnosis of BAD.  The metabolism of bile acids and their enterohepatic circulation, changes in the intestinal microbiome, biofilm formation, and effects on feedback.  Clinical trials related to intestinal transit and drug action.

Information

Funders

Recent work has been funded by the and charitable contributions.

Related Centres
  • University Hospitals Coventry & Warwickshire, Coventry
  • Diagnostics, Medicines and Healthcare products Regulatory Agency, London
  • Institute of Metabolic Science, University of Cambridge
  • Zealand University Hospital, Køge, and University of Copenhagen, Copenhagen, Denmark.
Useful links for patients
Collaborators
  • Professor Ramesh Arasaradnam
  • Professor Tricia Tan
  • Professor Fiona Gribble
  • Dr Chris Bannon
  • Dr Christan Borup
Recent publications
  1. Walters JRF. Making the diagnosis of bile acid diarrhea. Am J Gastroenterol 2020; 115:1974–1975
  2. Sagar NM, Duboc H, Kay GL, Alam MT, Wicaksono AN, Covington JA, Quince C, Kokkorou M, Svolos V, Palmieri LJ, Gerasimidis K, Walters JRF, Arasaradnam RP. The pathophysiology of bile acid diarrhoea: differences in the colonic microbiome, metabolome and bile acids.  Sci Rep 2020; 24;10:20436. doi: 10.1038/s41598-020-77374-7
  3. Balesaria S, Pattni SS, Johnston IM, Nolan JD, Appleby RN, Walters JRF. Common genetic variants in the bile acid synthesis enzyme CYP7A1 are associated with severe primary bile acid diarrhea. Gastroenterology 2022; 163: 517–519
  4. McGlone ER, Malallah K, Cuenco J, Wewer Albrechtsen NJ, Holst JJ, Vincent R, Ling C, Khan O, Verma S, Ahmed AR, Walters JRF, Khoo B, Bloom SR, Tan TMM. Differential effects of bile acids on the post-prandial secretion of gut hormones: a randomised crossover study.  Am J Physiol Endo 2021; 320: E671-E679
  5. Walters JRF. Treating bile acid diarrhoea with liraglutide. Lancet Gastroenterol Hepatol 2022; 7:897-899
  6. Walters JRF. Lessons from a trial of colesevelam for bile acid diarrhoea. Lancet Gastroenterol Hepatol 2023; 8:290-91
  7. Walters JRF, Sikafi R. Managing bile acid diarrhea: aspects of contention. Expert Rev Gastroenterol Hepatol 2024; 18:521-528
  8. Hillman EBM, Baumgartner M, Carson D, Amos GCA, Wazir I, Khan HA, Khan MA, Rijpkema SF, Walters JRF, Wellington EMH, Arasaradnam R, Lewis SJ. Changing gastrointestinal transit time alters microbiome composition and bile acid metabolism: a cross-over study in healthy volunteers. Neurogastroenterol Motil 2025;e70075
  9. Hillman EBM, Carson D, Walters JRF, Fritzsche M, Mate R, Chappell KE, Chekmeneva E, Gomez Romero M, Lewis SJ, Rijpkema S, Wellington EMH, Arasaradnam R, Amos GCA. Ruminococcus gnavus and biofilm markers in feces from primary bile acid diarrhea patients indicate new disease mechanisms and potential for diagnostic testing.  Gastro Hepatol Adv 2025; 4:100712 doi.org/10.1016/j.gastha.2025.100712
  10. Bannon CA, Walters JRF, Wu T, Kay R, Punnoose A, Spiller R, Wilson J, Verdino P, Barker P, Burling K, Horowitz M, Rayner CK, Ford AC, Reimann F, Gribble FM. Insulin like peptide 5 is released in response to bile acid in the rectum and is associated with diarrhoea severity in patients with bile acid diarrhoea. Gut 2025; doi:10.1136/gutjnl-2025-335393
Clinical trials
  • Bile acid diarrhoea and intestinal biofilms  IRAS 320842
  • Colesevelam tablets in bile acid diarrhoea  IRAS 1010417

Our researchers

Professor Julian Walters

Dr Sara Balesaria

Dr Sara Balesaria
Research officer

Dr Evette Hillman

Dr Evette Hillman
Visiting Researcher