Ethanol-Induced Dysbiosis and Systemic Impact: A Meta-Analytical Synthesis of Human and Animal Research

Abstract

Background: Chronic ethanol consumption is a major global health concern traditionally associated with liver disease. Ethanol disrupts gut microbial communities, compromises intestinal barrier function, and contributes to hepatic, metabolic, and neurocognitive disorders.

Methods: We conducted a systematic PubMed search and meta-analysis of 11 human and 19 animal studies evaluating ethanol-induced gut microbiota alterations. Studies were assessed for microbial diversity, taxonomic shifts, barrier integrity, and systemic effects. Effect sizes were calculated where possible, and interventional outcomes were examined.

Results: Across species, ethanol exposure was consistently associated with reduced microbial diversity and depletion of beneficial commensals such as Faecalibacterium, Lactobacillus, Akkermansia, and Bifidobacterium, alongside an expansion of proinflammatory taxa (Proteobacteria, Enterococcus, Veillonella). Our analysis uniquely highlights discrepancies between human and animal studies, including opposite trends in specific genera (e.g., Akkermansia and Bifidobacterium) and the impact of confounders such as antibiotic exposure in human cohorts. We also demonstrate that microbiota-targeted interventions can partially restore diversity and improve clinical or behavioral outcomes.

Conclusions: This meta-analysis highlights reproducible patterns of ethanol-induced gut dysbiosis across both human and animal studies.

Keywords: alcohol use disorder; dysbiosis; ethanol; fecal microbiota transplantation; gut microbiota; gut–liver axis; meta-analysis; microbiota–brain interaction; rodent models; short-chain fatty acids.

Figure 1

Total amount of alcohol consumed per adult (15+ years) over a calendar year, in liters of pure alcohol [1]. Data from WHO (Indicators).

Figure 2

Oxidative and non-oxidative metabolism of ethanol. Data from Biorender [5].

Figure 3

Ethanol and its metabolic impact. Created with Biorender [5]. Data from Madigan et al. [8].

Figure 4

Microbial dysbiosis and its disease associations. Created with Biorender [5]. Data from Szychlinska et al. [13].

Figure 5

Gut–brain axis. Created with Biorender [5]. Data from Gonzalez-Santana et al. [21].

Figure 6

PRISMA flow diagram. Created with Biorender [5]. Data from www.prisma-statement.org, accessed on 12 June 2025 [30].

Figure 7

Breakdown of participant diagnoses across the 11 human studies.

Figure 8

Meta-aggregated taxonomic alterations across all human studies. Data from [33,34,35,36,37,38,39,40,41,42,43].

Figure 9

Meta-aggregated taxonomic alterations across all animal studies. Data from [45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62].

Figure 10

Venn diagram showing differences and similarities in the change in intestinal microbiota between humans and animals. ↑ indicates an increase in bacterial abundance or clinical parameter; ↓ indicates a decrease.