Exclusive Effects of Moxibustion on Gut Microbiota: Protocol for a Focused Systematic Review and Meta-Analysis

Background: The gut microbiota (GM) plays a critical role in systemic health, influencing immune, metabolic, and neurological functions. There is emerging evidence suggesting that moxibustion, a traditional thermal therapy, may modulate the GM to restore microbial homeostasis, yet its exclusive effects remain undifferentiated from those of combined therapies such as acupuncture. Previous meta-analyses lack mechanistic specificity, necessitating a focused evaluation of moxibustion's impact on microbial ecology. Objective: This systematic review and meta-analysis aims to quantify moxibustion-induced changes in GM diversity, taxonomic composition, and functional metabolites (eg, short-chain fatty acids). Methods: We will systematically search the PubMed, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Wanfang, and VIP databases from inception to December 31, 2024, using keywords such as "moxibustion," "gut microbiota," and "intestinal flora." Eligible preclinical (animal) and clinical (human) studies evaluating stand-alone moxibustion interventions on the GM will be included. Primary outcomes include microbial α diversity indexes (Shannon and Simpson) and relative abundance of key taxa (eg, Firmicutes and Bacteroidetes). Risk of bias will be assessed using the Systematic Review Center for Laboratory Animal Experimentation risk-of-bias tool for animal studies and the modified Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies criteria for human trials. Pooled effect estimates for continuous outcomes (eg, diversity indexes and taxa ratios) will be calculated using the ratio of means with 95% CIs. Statistical analyses will be conducted in RevMan (version 5.4) and R (metafor package), with data archived on Figshare for reproducibility. Results: As of March 2025, the literature search and screening have been completed, and 31 studies meeting the inclusion criteria have been identified. The comprehensive analysis is scheduled to be completed by October 2025, with results anticipated to be published in late 2025. On the basis of previous work, an anticipated result is that moxibustion may reduce pathogenic genera such as Ruminococcus while enhancing beneficial genera, effects that are expected to be associated with improved intestinal barrier integrity and anti-inflammatory responses. Conclusions: This protocol provides a rigorous framework to evaluate moxibustion's unique role in GM modulation, bridging traditional medicine with microbiome science. The results will inform optimized, nonpharmacological strategies for managing microbiome-associated chronic diseases and guide future research priorities.