KEGG pathway enrichment analysis of the differentially expressed proteins in the livers of the two groups revealed that exposure to L-Phe significantly reduced pathways related to PPARα and unsaturated fatty acid biosynthesis (Fig. 3H and I), where deficiency of unsaturated fatty acids has been linked to impaired mitophagy and the progression of liver steatosis in MASLD (Spooner and Jump 2023; Gortan Cappellari et al. 2022; Li et al. 2024). This evidence concerns the gene PPARA and fatty liver disease.