The function of MDH1 (malate dehydrogenase 1, Ensembl gene identifier ENSG00000014641) is as follows. Catalyzes the reduction of aromatic alpha-keto acids in the presence of NADH (PubMed:2449162, PubMed:3052244). Plays essential roles in the malate-aspartate shuttle and the tricarboxylic acid cycle, important in mitochondrial NADH supply for oxidative phosphorylation (PubMed:31538237). Catalyzes the reduction of 2-oxoglutarate to 2- hydroxyglutarate, leading to elevated reactive oxygen species (ROS) (PubMed:34012073). {ECO:0000269|PubMed:2449162, ECO:0000269|PubMed:3052244, ECO:0000269|PubMed:31538237}.