The Effect of a Ketogenic Diet on Liver Health: A Systematic Review and Meta-Analysis

CONTEXT: In the absence of long-term research with respect to the impact of a ketogenic diet (KD) on liver disease progression, further investigation into the screening for liver enzymes is useful in attempting to elucidate whether a KD may result in positive or negative effects. OBJECTIVE: The goal of this study was to thoroughly examine how a KD affects liver health. DATA SOURCES: The PubMed/Medline, Web of Science, Scopus, Cochrane Library, and Embase databases were searched to find pertinent randomized controlled trials (RCTs). DATA EXTRACTION: This systematic review featured 20 RCTs investigating the impact of a KD on liver enzymes and liver stiffness. A random-effects model analysis was undertaken, yielding pooled weighted mean differences and 95% CIs. DATA ANALYSIS: A quantitative meta-analysis showed that a KD has a significant lowering effect on levels of aspartate aminotransferase (AST) [weighted mean difference (WMD): -3.56 U/L; 95% CI: -6.61, -0.51], alanine aminotransferase (ALT) (WMD: -3.03 U/L; 95% CI: -5.26, -0.81), gamma-glutamyl transferase (GGT) (WMD: -12.25 U/L; 95% CI: -22.08, -2.42), and alkaline phosphatase (ALP) (WMD: -5.29 U/L; 95% CI: -9.85 to -0.74). However, the findings obtained from the meta-analysis showed that a KD has no significant effect on liver fibrosis (liver stiffness) (WMD: 0.40; 95% CI: -0.23, 1.04). The findings also showed that a KD followed for a duration of less than 12 weeks caused greater reductions in liver enzymes, including AST, ALT, and GGT, in people with a BMI of less than 30. CONCLUSIONS: In general, KDs can reduce traditional liver enzyme levels (ALT, AST, ALP, and GGT), but they appear to have no significant effect on liver stiffness.