Energy Metabolism for Skin Cells: Skin cells require constant energy for functions like cell turnover (renewal), repair, and protection against environmental stressors. NAD+ acts as an electron acceptor in oxidative phosphorylation, providing the energy needed for these processes.

DNA Damage Repair (DDR) Support: The skin contains dead skin cells that need regular renewal, which involves DNA replication and repair. NAD+ is essential for nucleotide excision repair (NER), a critical DDR pathway in skin cells, helping to fix damaged DNA and protect the genome.