Mitochondria

Mitochondria are double-membrane-bound organelles present in nearly all eukaryotic cells, often described as the powerhouses of the cell due to their central role in generating adenosine triphosphate (ATP) through oxidative phosphorylation. A single cell can contain hundreds to thousands of mitochondria, with energy-demanding tissues like the heart, brain, and skeletal muscle containing the highest densities. Beyond energy production, mitochondria are involved in calcium homeostasis, reactive oxygen species generation and signalling, apoptosis, and the synthesis of certain amino acids and steroids. Mitochondrial dysfunction is increasingly recognised as a hallmark of aging, driven in part by declining NAD+ levels that impair oxidative phosphorylation and sirtuin-mediated mitochondrial quality control. NAD+ supplementation research aims to restore mitochondrial function by replenishing this critical coenzyme.