Demonstrating the Beneficial Effect of Low Protein Diet in Primary Sclerosing Cholangitis through a Randomized Clinical Trial and Multi-omics Data Analysis

Primary sclerosing cholangitis (PSC), a progressive cholestatic hepatobiliary disease characterized by inflammation and fibrosis of the bile ducts, has a pathophysiology that is not understood. No effective therapies exist. The only treatment option for PSC is liver transplant. We undertook a pilot randomized trial of diet to investigate the pathophysiology of the disease, the role of diet and to advance potential therapy. We enrolled 20 patients with PSC and randomly assigned them to a Low Protein/low sulfur Diet (LPD, n=10) or the Specific Carbohydrate Diet (SCD, n=10) for 8 weeks. Results showed that low protein intake benefits PSC patients, whereas higher protein levels exacerbate the condition. We further identified gut bacterial markers useful for distinguishing LPD responders (mostly PSC with concomitant ulcerative colitis) from non-responders. Additionally, by integrating multi-omics data, we propose that this diet modifies the intestinal sulfur cycle reducing hydrogen sulfide (H2S) production. Our findings provide an understanding of the beneficial effect of LPD as well as insights into a possible key driver of inflammation in PSC. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT04678219 ### Funding Statement This work was supported by the Resnek Family Center for PSC Research. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of Brigham and Women's Hospital gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors