Article - Gut Microbiota and Liver Health: Meta-Analysis of -Containing Probiotics in NAFLD Management.

Expert Review

Reviewer: Chloe Steele

21st Oct 2025

Conflict of interest

None

Take home message

Bifidobacterium supplementation may be of benefit for both metabolism and inflammation in individuals with NAFLD.

Evidence category

A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)

Summary review

Introduction

· Non-alcoholic fatty liver disease (NAFLD) can increase the risk for cardiometabolic disease. Bifidobacterium may support those with liver disease through its actions on metabolic function.

· This meta-analysis aimed to determine whether Bifidobacterium supplementation could improve cardiometabolic risk indicators in individuals with NAFLD.

Method

· This was a meta-analysis of 24 studies using PRISMA guidelines.

· Primary outcomes were liver fat content, liver injury markers, inflammatory cytokines, body mass index, and lipid profile.

· Secondary outcomes were fasting plasma glucose, fasting insulin, homeostasis model assessment for insulin resistance (HOAMA-IR), glycated haemoglobin (HbA1_c), and blood pressure.

Results

· Supplementation improved liver injury markers (alanine amino transferase (ALT); SMD: −0.411, 95% CI: −0.581 to −0.241; I2 = 50.111%, p = 0.006 and gamma-glutamyl transferase; SMD = −0.442, 95% CI: −0.664 to −0.220; I2 = 50.1%, p = 0.024).).

· Effects on ALT were most pronounced in Iranian subjects (p = 0.002) compared to individuals from the United Kingdom (p = 0.593), Malaysia (p = 0.272), and Ukraine (p = 0.207).

· Moderate effects were seen on aspartate amino transferase (SMD = −0.563, 95% CI: −0.726 to −0.400; I2 = 36.3%, p = 0.063), and liver fat content (SMD = −0.555, 95% CI: −0.728 to −0.383; I2 = 20.6%, p = 0.241).

· Supplementation improved lipid metabolism with lower total cholesterol (p = 0.007), triglycerides (%, p = 0.208), and low density lipoprotein cholesterol (p = 0), without changing high-density lipoprotein levels (p = 0.405).

· Supplementation improved glycaemic regulation in the short-term, with improvements to fasting blood glucose (SMD: −0.364, 95% CI: −0.581 to −0.147; I2 = 54.496%, p = 0.012). However, long term changes as indicated by HbA1_c remained unaffected (SMD: −0.070, 95% CI: −0.340 to 0.199; I2 = 0%, p = 0.931).

· Supplementation had an anti-inflammatory effect.

· Blood pressure remained unaffected by Supplementation.

Conclusion

· This meta-analysis concluded that Bifidobacterium supplementation can improve metabolic and inflammatory markers in individuals with NAFLD.

Clinical practice applications

Having a healthy gut microbiota is important for managing metabolic and inflammatory markers associated with poorer outcomes in NAFLD.
Many of the studies included in the meta-analysis were from combination probiotics, with many of them also containing Lactobacillus, other probiotic strains, vitamin E and symbiotics such as fructooligosaccharides and inulin . Therefore benefits may only be seen when combination probiotics and symbiotics are used.
Dosages and forms of delivery used in the studies ranged extensively. Yoghurts, capsules, and sachets were all used in the included studies and dosages ranged from 300g of yoghurt to 64 billion CFU/day. For clinicians seeking dose recommendations, individual papers and further research needs to be completed.
Combination Bifidobacterium supplementation may have metabolic and inflammatory benefits for those with NAFLD if given in the short-term.

Considerations for future research

Future research should focus on assessing changes in NAFLD.
Gut microbiota can be influenced by sex hormones and future research should focus on any gender differences associated with Bifidobacterium supplementation and NAFLD to ensure a more personalised approach.

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Abstract

Diseases, including cardiovascular disease, type II diabetes, and metabolic syndrome, are leading causes of morbidity and mortality worldwide. Non-alcoholic fatty liver disease (NAFLD) is commonly associated with these conditions through shared pathophysiological mechanisms such as insulin resistance, chronic inflammation, and dyslipidemia. Emerging evidence suggests that probiotic formulations containing Bifidobacterium species may support cardiometabolic health by modulating gut microbiota composition. This meta-analysis aimed to assess the efficacy of Bifidobacterium-containing probiotic combinations in improving key cardiometabolic parameters, including lipid profiles, blood pressure, glycemic indices, and inflammatory biomarkers among individuals with NAFLD. A systematic literature search was conducted across PubMed, Embase, the Cochrane Library, and Web of Science databases to identify relevant randomized controlled trials (RCTs) published up to December 2024. A total of 24 RCTs involving 1611 participants met the inclusion criteria. The pooled results demonstrated significant reductions in total cholesterol, triglycerides, and low-density lipoprotein cholesterol following probiotic intervention. Improvements were also observed in fasting glucose levels and inflammatory markers, including high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Although modest improvements were noted in NAFLD severity, the effects on liver injury markers were relatively limited. These findings suggest that Bifidobacterium-based probiotic combinations may provide cardiometabolic benefits, particularly in lipid regulation, glucose metabolism, and inflammatory control. Further large-scale, well-designed RCTs are warranted to validate these results and to determine the most effective probiotic strains, compositions, and treatment durations.