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The effect of oral synbiotics on the gut microbiota and inflammatory biomarkers in healthy adults: a systematic review and meta-analysis

Cosier DJ, Lambert K, Neale EP, Probst Y, Charlton K

Nutrition reviews, 2025

1,319 participants · 14 citations

Abstract

Context: Prior research has explored the effect of synbiotics, the combination of probiotics and prebiotics, on the gut microbiota in clinical populations. However, evidence related to the effect of synbiotics on the gut microbiota in healthy adults has not been reviewed to date.

Objective: A systematic review and meta-analysis was conducted to comprehensively investigate the effect of synbiotics on the gut microbiota and inflammatory markers in populations of healthy adults.

Data sources: Scopus, PubMed, Web of Science, ScienceDirect, MEDLINE, CINAHL, and The Cochrane Library were systematically searched to retrieve randomized controlled trials examining the primary outcome of gut microbiota or intestinal permeability changes after synbiotic consumption in healthy adults. Secondary outcomes of interest were short-chain fatty acids, inflammatory biomarkers, and gut microbiota diversity.

Data extraction: Weighted (WMD) or standardized mean difference (SMD) outcome data were pooled in restricted maximum likelihood models using random effects. Twenty-seven articles reporting on 26 studies met the eligibility criteria (n = 1319).

Data analysis: Meta-analyses of 16 studies showed synbiotics resulted in a significant increase in Lactobacillus cell count (SMD, 0.74; 95% confidence interval [CI], 0.15, 1.33; P = 0.01) and propionate concentration (SMD, 0.22; 95% CI, 0.02, 0.43; P = 0.03) compared with controls. A trend for an increase in Bifidobacterium relative abundance (WMD,…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 1,319 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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