The Multifaceted Influence of Beta-Hydroxybutyrate on Autophagy, Mitochondrial Metabolism, and Epigenetic Regulation

Beta-hydroxybutyrate (BHB), a key ketone body produced during fatty acid metabolism, plays critical roles in various physiological and pathological conditions. Synthesized in the liver through ketogenesis, BHB serves as an essential energy substrate during glucose deprivation, supporting survival by efficiently utilizing fat reserves. It crosses the blood-brain barrier, providing energy for neuronal function, enhancing cognitive processes such as learning and memory, and offering neuroprotection by modulating synaptic plasticity and neurotransmitter levels. BHB's impact extends to cellular pathways, including autophagy, mitochondrial biogenesis, and epigenetic regulation. By modulating autophagy, BHB ensures mitochondrial integrity and function through intricate molecular pathways involving AMPK, mTOR, PINK1/Parkin, and others. This regulation plays vital roles in neurodegenerative diseases, metabolic disorders, cancer, and cardiovascular diseases, reducing oxidative stress and preventing cellular dysfunction. Epigenetically, BHB acts as an endogenous histone deacetylase inhibitor, inducing beneficial histone modifications that enhance cellular resilience and stress responses. This epigenetic influence is crucial in conditions like diabetes and cancer, aiding insulin secretion, protecting pancreatic beta cells, and impacting cancer cell gene expression and survival. Furthermore, BHB's therapeutic potential is evident in its ability to improve mitochondrial function across various tissues, including neurons, muscle, and liver. By enhancing mitochondrial respiration, reducing oxidative stress, and altering metabolic pathways, BHB mitigates conditions such as ICU-acquired weakness, nonalcoholic fatty liver disease, and cardiovascular diseases. BHB's modulation of autophagy and epigenetic regulation underscores its comprehensive role in cellular homeostasis and health across multiple physiological contexts, providing a foundation for future therapeutic strategies.