Chinese Medicine Enemas for Ulcerative Colitis: Mechanisms and Optimal Duration from a Systematic Review and Meta-Analysis

Summary

This meta-analysis of 20 animal studies (980 subjects) shows compound Chinese medicine enemas significantly improve ulcerative colitis indicators via anti-inflammation, intestinal barrier enhancement, and gut microbiota modulation. Optimal duration: 10–28 days. Despite promising results, high heterogeneity and low study quality urge caution; high-quality trials are needed for validation.

Abstract

This systematic review and meta-analysis aimed to elucidate the mechanisms underlying the efficacy of Chinese medicine enema formulations in animal models of ulcerative colitis (UC) and to provide a scientific basis for their potential clinical application. Comprehensive searches of PubMed, Web of Science, Cochrane Library, Elton B. Stephens Company (EBSCO), and ScienceDirect identified relevant animal studies published up to December 2024. Methodological quality was assessed using the SYRCLE risk of bias tool, and statistical analyses were conducted with RevMan 5.3 and Stata 15.

Twenty studies comprising 980 animals were included, with quality scores ranging from 2 to 6. Chinese medicine enemas significantly reduced histological colitis score, disease activity index, spleen index, colon damage score, and inflammatory mediators including IL-6, TNF-α, IL-1β, IL-8, COX-2 mRNA, and myeloperoxidase. They also improved body weight change, colon length, intestinal tight junction proteins (ZO-1, Occludin), IL-10 expression, and regulatory T-cell levels (CD4⁺CD25⁺FOXP3⁺), while modulating gut microbiota composition, particularly Firmicutes and Bacteroides.

These findings suggest that the therapeutic benefits of Chinese medicine enemas may derive from anti-inflammatory activity, enhancement of intestinal barrier integrity, and regulation of gut flora. However, substantial heterogeneity—likely due to differences in animal species, sex, and intervention duration—and generally low methodological quality limit the strength of the evidence. Further well-designed, high-quality preclinical and clinical studies are warranted to confirm efficacy, optimize treatment protocols, and evaluate safety for human application.

Introduction

Inflammatory bowel disease (IBD) comprises two primary types: ulcerative colitis (UC) and Crohn's disease (CD). Research indicates that genetics, environmental factors, microbial interactions, and immune dysregulation are involved in the pathogenesis of IBD¹. Emerging evidence suggests an increasing incidence of IBD in developing countries². UC is characterized by recurrent episodes of abdominal pain, diarrhea, and rectal bleeding³. Improvement of clinical symptoms and reduction of recurrence in UC patients are crucial objectives in clinical management⁴.

Protocol

All included animal studies adhered to the ARRIVE guidelines and had been approved by their respective institutional ethics committees. Blinding and randomization conducted in accordance with the SYRCLE guidelines. The review complied with PRISMA reporting standards (ID: CRD42024527636). All procedures were performed under ethical clearance to minimize bias and animal harm.

1. Software installation and preparation

1.  Install RevMan (version 5.3, Cochrane Collaboration, https://revman.cochrane.org).
   1. Access the RevMan official website (see Table of Materials).
   2. Download th....

Results

A total of 1,146 potentially relevant articles were identified from five databases, comprising 65 from PubMed, 92 from Web of Science, 56 from EBSCO, none from the Cochrane Library, and 933 from Science Direct. After the removal of 91 duplicate records, 1,055 articles remained.

Subsequently, the full texts of these articles were reviewed, resulting in the exclusion of 1,035 articles based on the predefined exclusion criteria. Ultimately, twenty studies met the eligibility criteria and were inc.......

Discussion

This study aimed to investigate the protective effects and underlying mechanisms of compound Chinese medicine enema in animal models of ulcerative colitis. A total of 20 papers involving 980 animals were included. The compound Chinese medicine enema was found to improve several clinical symptoms of ulcerative colitis, including colon length, disease activity index, histological colitis score, body weight change, spleen index, and colon damage score. Moreover, the enema demonstrated modulation of various inflammatory mark.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Cochrane Library	Cochrane Library	https://www.cochranelibrary.com/
EBSCO	EBSCO Industries	https://www.ebsco.com/
Endnote X9	Cochrane	https://support.clarivate.com/Endnote/s/
GetData	GetData Graph Digitizer	https://getdata-graph-digitizer.com/
PROSPERO	National Institute for Health and Care Research	https://www.crd.york.ac.uk/PROSPERO/
PubMed	National Library of Medicine	https://pubmed.ncbi.nlm.nih.gov/
RevMan	Cochrane	https://revman.cochrane.org/
ScienceDirect	Elsevier	https://www.sciencedirect.com/
STATA	StataCorp	https://www.stata.com/
Web of Science	Clarivate Analytics	https://www.webofscience.com/