Targeting lipid disorders with washed microbiota transplantation in statin-free adults: a systematic review and meta-analysis

Abstract Background Dyslipidemia constitutes one of the foremost metabolic abnormalities contributing to cardiovascular morbidity and mortality. Washed microbiota transplantation (WMT), a refined form of fecal microbiota transplantation, has emerged as a novel therapeutic option targeting gut-liver axis dysregulation. This systematic review and meta-analysis, registered on PROSPERO (CRD42025645142), evaluated the efficacy of WMT in modulating lipid profile parameters. A comprehensive search was conducted across PubMed, Scopus, EMBASE, CENTRAL, Google Scholar, and ClinicalTrials.gov for studies assessing WMT effects on total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG). Eligible studies included adults receiving WMT without concurrent lipid-lowering or microbiota-modifying therapies. Data were pooled using random-effects meta-analysis. MINORS tool was used to assess methodological quality. Results Seven studies encompassing 1,163 participants were included. Across all study groups, WMT significantly reduced short-term TC (MD = –0.18; 95% CI –0.32 to –0.03) and long-term TG (MD = –0.08; 95% CI –0.11 to –0.05). LDL-C showed a significant long-term decrease (MD = –0.24; 95% CI –0.46 to –0.02), whereas HDL-C changes were non-significant overall. In participants with baseline hyperlipidemia, WMT consistently improved TC (short- and medium-term) and HDL-C (short-term), while effects on LDL and TG remained non-significant. Meta-regression demonstrated that higher baseline TC, HDL-C, and TG levels predicted greater post-WMT improvements (all p < 0.01). The overall certainty of evidence was low for most outcomes due to heterogeneity and observational study design. Conclusion WMT may improve lipid profiles, especially in patients with elevated baseline lipids, offering a microbiota-based adjunct for dyslipidemia management. High-quality RCTs and optimized protocols are needed to confirm long-term efficacy.