Effects of Animal-Based Foods on Metabolic Outcomes in Adults with MASLD and Comorbidities: A Systematic Review of Randomized Controlled Trials (2020–2026)

Background: Metabolically dysfunction-associated steatotic liver disease (MASLD) is a growing public health challenge linked to obesity and metabolic dysregulation. Since pharmacological options are limited, Mediterranean (MED) and DASH patterns are recommended. These diets include animal-derived foods, providing essential nutrients but also potential saturated fats. Objective: This updated systematic review aims to evaluate evidence from randomized controlled trials (RCTs) regarding the effects of specific animal-based foods on metabolic, hepatic, and anthropometric outcomes in adults with MASLD. Methods: A systematic search of nine databases (including PubMed, Scopus, and Embase) and trial registries (ClinicalTrials.gov) was conducted for RCTs published between January 2020 and 31 March 2026. Participants were adults (18–65 years) with MASLD. Interventions included animal-derived foods typical of MED/DASH. Outcomes focused on hepatic function, lipid profiles, glycemic control, and anthropometry. Risk of bias was assessed using the Cochrane RoB 2.0 tool. Results: A total of seven RCTs demonstrated food-specific and heterogeneous effects. Freshwater fish and vitamin D-fortified probiotic yogurt showed consistent benefits for glycemic control and lipid profiles. Fish oil and omega-3 supplementation led to modest improvements in lipids and hepatic markers. Ghee intake was linked with improved total cholesterol and liver enzyme (ALP). Red meat demonstrated heterogeneous effects depending on dose and background dietary pattern. Most studies exhibited limited concerns regarding risk of bias. Discussion: Animal-based foods within MED/DASH patterns exert distinct effects in MASLD. Freshwater fish and fortified yogurt appear most beneficial. The evidence is limited by small sample sizes in specific food categories and variability in dietary assessment methods. These findings support nuanced, evidence-based recommendations for MASLD management.