Microalgae Oil Improves Hepatic Lipid Metabolism in A High-Fat Diet-Induced Mouse Model

Metabolically, dysfunctional steatotic liver disease is a prevalent metabolic disorder associated with gut microbiota dysbiosis and hepatic lipid imbalance. In this study, a high-fat diet-induced mouse model was established to evaluate the effects of supplementation with DHA-rich microalgae oil. Mice (n = 4 per group) were fed a high-fat diet for 8 weeks and received daily oral administration of microalgae oil, probiotics, or the combination of DHA-rich microalgae oil and probiotics. Metabolic parameters, gut microbiota composition (16S rRNA sequencing), microbial functional pathways, and hepatic metabolomic profiles were assessed. The results showed that DHA-rich microalgae oil improved lipid homeostasis, as indicated by reduced serum LDL-c and hepatic triglyceride levels and increased high-density lipoprotein (HDL-c), and was associated with alleviation of liver injury and oxidative stress. Microbiome analysis revealed selective changes in gut microbial composition, including enrichment of Lactobacillus and Bifidobacterium and reduction of high-fat diet-associated taxa such as Clostridium and Ruminococcus. Functional profiling indicated alterations in microbial metabolic pathways, including the L-methionine salvage cycle and phenylethylamine degradation. Integrated microbiome-metabolome analysis further identified associations between microbial taxa and hepatic metabolites involved in fatty acid metabolism, bile acid turnover, and amino acid pathways. These findings indicate that DHA-rich microalgae oil supplementation is associated with improvements in hepatic lipid metabolism and gut microbiota composition in this model, without implying a direct causal mechanism.