Effects of Canola Oil on Hepatic and Cardiometabolic Markers in Non-Alcoholic Fatty Liver Disease: A Systematic...

Non-alcoholic fatty liver disease (NAFLD) is closely associated with obesity, insulin resistance, and increased cardiometabolic risk. Dietary fat quality has emerged as a modifiable factor in NAFLD management; however, the specific effects of canola oil on hepatic and metabolic markers remain unclear. This systematic review and meta-analysis evaluated randomized controlled trials investigating the effects of canola oil consumption in adults with NAFLD. Searches were conducted in PubMed, Web of Science, Scopus, and Cochrane Library databases through December 2024 in accordance with PRISMA guidelines (PROSPERO: CRD42024593566). Random-effects models were applied to estimate pooled effect sizes. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool, and certainty of evidence was graded using the GRADE framework. Three randomized controlled trials (four intervention arms; n = 220 participants) were included. Canola oil consumption was associated with significant reductions in alanine aminotransferase (ALT) (effect size: -0.472, 95% CI: -0.711 to -0.233; p < 0.001) and aspartate aminotransferase (AST) (effect size: -0.505, 95% CI: -0.745 to -0.264; p < 0.001). Triglyceride levels were also significantly reduced (effect size: -0.593, 95% CI: -1.151 to -0.036; p = 0.037), although heterogeneity was substantial. No significant effects were observed for HDL (effect size: 0.154, 95% CI: -0.604 to 0.912; p = 0.69) or gamma-glutamyl transferase (GGT) (effect size: 0.156, 95% CI: -0.173 to 0.486; p = 0.352). The certainty of evidence was moderate for ALT and low for AST, triglycerides, HDL, and GGT, primarily because of small sample sizes and clinical heterogeneity. Dietary canola oil may contribute to modest improvements in hepatic enzymes and triglyceride levels in adults with NAFLD. However, the limited number of trials, variability in intervention protocols, and absence of long-term clinical outcomes warrant cautious interpretation. Larger, well-designed studies are needed to clarify its role within cardiometabolic risk management strategies for NAFLD.