NAD and longevity markers: what we know, what's hype

NAD+ IV drips sell at $400-800 a session. NMN bottles have become the supplement aisle's hottest trend. Meanwhile, the labs with the strongest longevity evidence - ApoB, HbA1c, fasting insulin - are the ones most "biohackers" never check. Here's the honest read on NAD, and the five labs that actually move the longevity math.