NAD+ and Aging: What the Science Actually Says vs What Supplements Sell

01 The NAD+ Decline

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme essential for cellular energy metabolism, DNA repair, and sirtuin activation. Levels decline with age: a 60-year-old has roughly half the NAD+ of a 20-year-old. This decline correlates with many age-related diseases. The supplement industry has built a $2 billion market on the promise that restoring NAD+ will slow aging. The science is more nuanced.

02 What Works

NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide) are NAD+ precursors that effectively raise blood NAD+ levels in humans. Multiple trials confirm this. The question isn't whether supplements raise NAD+ — they do. The question is whether raising NAD+ improves health outcomes. The evidence here is mixed: some trials show improved insulin sensitivity in prediabetic adults. Others show no effect on physical function in healthy elderly adults. The benefit, if any, appears to be in metabolically compromised populations.

03 What Doesn't Work

Direct NAD+ supplements (the molecule itself) don't work orally — NAD+ is broken down in the digestive tract. IV NAD+ infusions ($500-1000 per session) raise levels temporarily but return to baseline within 24 hours. The 'NAD+ drip' clinics are selling a transient effect with no evidence of long-term benefit. The honest summary: NAD+ precursors (NR, NMN) are promising but unproven for lifespan extension. Direct NAD+ is mostly marketing.