Integrating preclinical and clinical evidence: a meta-analysis of probiotic/synbiotic interventions on metabolic syndrome

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• Picked for Biochemistry (medical) (paper of the day, 2 November 2026): Metabolic syndrome review synthesizes clinical biochemical intervention outcomes

Abstract

BACKGROUND: Published meta-analyses present inconsistent findings regarding the effects of probiotics on metabolic syndrome (MetS), with most lacking in-depth mechanistic exploration. OBJECTIVE: To systematically assess the efficacy of probiotic/synbiotic interventions for MetS across preclinical and clinical settings, and to explore underlying mechanisms by quantifying inflammatory and metabolic biomarkers. METHODS: We systematically searched PubMed, Embase, the Cochrane Central Register of Controlled Trials, CNKI, and Wanfang Data from inception to June 10, 2025. Both animal and clinical studies were included. For outcomes reported in different units, all values were standardized to a single common unit prior to pooling. Meta-analyses were performed using Stata 15.0 to calculate pooled mean differences (MD) and 95% confidence intervals (CIs). Sensitivity and subgroup analyses were used to assess result stability and heterogeneity. RESULTS: This meta-analysis of 35 studies (12 clinical trials with 696 MetS patients and 23 animal studies) demonstrated significant metabolic improvements with probiotic/synbiotic interventions. In animal models, these interventions can significantly improve body weight (BW) (MD = -13.27 g, 95%CI: -18.66,-7.88), glucose metabolism (fasting plasma glucose (FPG), MD = -41.05 mg/dL, 95%CI: -46.50, -35.60; HbA1c, MD = -1.17%, 95%CI: -1.50, -0.84), lipid metabolism (TG, MD = -51.38 mg/dL, 95%CI: -71.46, -31.30; TC, MD = -36.66 mg/dL, 95%CI: -50.10, -23.22), inflammatory and metabolic targets (IL-6, MD = -15.07 pg./mL, 95%CI: -18.23, -11.91; Leptin, MD = -20.95 ng/mL, 95%CI: -39.79, -2.11; FFA, MD = -130.36 μmol/L, 95%CI: -191.52, -69.21), as well as liver function indicators in animal models of MetS. In patients, changes in FPG were non-significant (MD = -8.76 mg/dL, 95%CI:-18.29,0.77), whereas significant improvements were observed for BW (MD = -1.06 kg, 95%CI:-1.70,-0.42), waist circumference (MD = -2.12 cm, 95%CI:-3.70,-0.55), and lipid profiles: TG (MD = -20.51 mg/dL, 95%CI:-27.69,-13.34), TC (MD = -12.09 mg/dL, 95%CI:-16.15,-8.04), LDL-C (MD = -10.56 mg/dL, 95%CI:-14.96,-6.17), and HDL-C (MD = 1.97 mg/dL, 95%CI:0.55,3.39). Sensitivity analyses confirmed result stability, with low risk of publication bias. CONCLUSION: Probiotic and synbiotic supplementation effectively improves body composition and lipid metabolism in MetS patients and animal models, and improves glucose metabolism in animals. In MetS patients, supplementation reduces HbA1c without altering FPG. These interventions produce favorable changes in adipokines, inflammatory cytokines and metabolic stress markers. Further high-quality, long-term RCTs are required to validate these effects and optimize intervention strategies. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/, identifiers CRD420261373917 and CRD420261374049.

Abstract as published, via PubMed.