Magnesium as a Bioenergetic Checkpoint Linking Mitochondrial Function, Metabolic Disease, and Aging

Magnesium is traditionally viewed as a permissive electrolyte required for cellular viability. Emerging evidence, however, reveals a more central role for Mg²⁺ as an active regulator of mitochondrial bioenergetics and metabolic resilience. In this Review, we synthesize recent advances in renal magnesium handling, mitochondrial Mg²⁺ transport, and MgATP chemistry to propose a unifying framework in which magnesium functions as a bioenergetic checkpoint. At the cellular level, Mg²⁺ availability specifies the functional pool of ATP, constrains kinase signaling, and stabilizes mitochondrial performance by limiting calcium overload and oxidative stress. At the tissue and organismal levels, disruption of magnesium homeostasis contributes to metabolic inflexibility, insulin resistance, acute kidney injury, and the progressive decline in stress tolerance that accompanies aging. We further discuss how age-associated drift in mitochondrial magnesium may act as a hidden temporal regulator that lowers the threshold for cellular senescence. Finally, we outline emerging therapeutic strategies, including transport-informed and compartment-specific approaches, that move beyond nonspecific supplementation toward precision modulation of magnesium-dependent bioenergetics. Together, this framework positions magnesium as a mechanistic link between mitochondrial function, metabolic disease, and aging, with broad implications for translational intervention.