NAD+ 101: How It Works | Energy, Aging, and the Biology of NAD

NAD⁺ is one of the most important molecules in human biology — essential for energy production, cellular repair, and metabolic regulation. But what actually is NAD⁺, how does it work inside the body, and why does it decline with age? In this long-form deep dive, I break down: What NAD⁺ is and why it’s required for life The NAD⁺ / NADH cycle and the salvage pathway How NR, NMN, and niacin support NAD⁺ production (and why most human studies focus on these) What we know — and don’t know — about NAD⁺ injections Oral precursors vs injectable NAD⁺: pros, cons, and biological rationale Why NAD⁺ declines with age (CD38, sirtuins, PARP, NNMT, inflammation) Common side effects reported with NAD⁺ injections and why they may occur This is not a sales pitch. This is a science-based explanation of NAD⁺ biology, grounded in primary research. About me: I’m a PhD scientist with a background in molecular biology and cellular pathways. I’m not a medical doctor and I don’t treat patients. Everything discussed here is for educational purposes only and based on published scientific literature.