Exploring the Role of Extra Virgin Olive Oil (EVOO) in MASLD: Evidence from Human Consumption

Background/Objectives: Metabolic dysfunction-associated steatosis liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD) is the leading cause of liver related morbidity and mortality affecting 38% of the adult global population. As of now, there is no clear consensus on a standardized pharmacological treatment for MASLD; therefore, lifestyle interventions particularly diet and exercise remain the first-line approach for both prevention and management. Extra virgin olive oil (EVOO), the primary source of fat in the Mediterranean diet. (MD) is widely recognized as a key contributor to its well-documented health benefits. As a central component of this dietary pattern, EVOO has demonstrated promising therapeutic potential due to its high phenolic content. The primary aim of this review is to synthesize existing human studies examining the effects of olive oil primarily EVOO on key pathological features of MASLD. Methods: A systematic search of human clinical and observational studies was conducted across major databases. Key outcomes assessed include hepatic steatosis, inflammation, oxidative stress, fibrosis, liver enzymes, and anthropometric measures. Study quality was evaluated using the Academy of Nutrition and Dietetics Quality Criteria Checklist. Results: This review included 25 high-quality studies, 12 of which assessed olive oil alone and 13 evaluated the MD emphasizing extra virgin olive oil (EVOO). EVOO-rich interventions consistently improved hepatic steatosis, liver enzyme levels (ALT, AST), and inflammatory markers in MASLD patients, particularly when paired with calorie-restricted or MD patterns. Benefits were dose- and type-dependent, with EVOO showing superior effects compared to refined olive oils. Modest improvements in lipid profiles and insulin resistance were observed. Longer study durations and higher EVOO intake (>30-50 g/day) yielded greater improvements. Findings suggest EVOO may exert beneficial effects on liver health through its anti-inflammatory and antioxidant properties. Future studies on EVOO's role in MASLD should use well-characterized oils with known polyphenol and bioactive compound levels and include clear biomarkers of oxidative stress, inflammation, and liver health outcomes on humans. Overall, EVOO represents a promising, non-pharmacological strategy for MASLD prevention and management. Conclusions: Current evidence suggests that EVOO, particularly when rich in phenolic compounds, is a promising dietary strategy for managing MASLD due to its hepato-protective effects, especially within a Mediterranean diet framework. However, findings are limited by study heterogeneity and a lack of high-quality randomized controlled trials, highlighting the need for future research to refine optimal dosing, assess long-term outcomes, and clarify underlying mechanisms.