The short version
NAD+ is one of the most important molecules in your body. It sits at the centre of how every cell converts food into usable energy and runs essential repair processes. The problem is that NAD+ levels drop significantly with age — research suggests by roughly 50% between your 20s and 60s. The supplements most people take are not NAD+ itself but precursors — NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) — that the body converts into NAD+. Those precursors reliably raise blood NAD+ levels. Whether that translates into the energy, performance and anti-aging benefits people hope for is where the picture becomes more nuanced.
How it works — in plain English
Every cell in your body runs on a molecule called ATP — the energy currency. NAD+ is the molecule that makes ATP production possible. It also powers sirtuins, a family of proteins involved in DNA repair, inflammation control and how cells respond to stress. Think of NAD+ as the fuel that keeps your cellular maintenance crew running. As it drops with age, maintenance slows. Supplementing with NMN or NR gives the body the raw material to make more.
What the research actually shows
There is a clear and consistent finding, and a more complicated one alongside it.
What is clear: oral NMN and NR reliably and significantly raise NAD+ levels in the blood. Multiple well-conducted trials confirm this consistently. The biochemical target is hit.
What is less clear: whether raising that biomarker produces the downstream benefits people are after — better energy, sharper thinking, stronger muscle performance, slower aging. Some trials have found specific gains (improved cholesterol, reduced blood pressure in certain sub-groups, better muscle endurance). Others have found no measurable difference versus placebo on the same metrics. The honest position is that the biology is compelling and the supplements are well tolerated, but we are still waiting for large, long-term trials to confirm which functional benefits are real and in which populations.