Celebrity hype has turned nicotinamide adenine dinucleotide, known as N.A.D.+, into a multi‑million‑dollar supplement aisle staple. Gwyneth Paltrow, Kendall Jenner and Andrew Huberman have all touted the product, while retailers from Walgreens to Walmart stock it alongside other anti‑aging pills. Sales surged despite scant human data, prompting investors to pour capital into firms marketing the molecule. Analysts estimate the segment could reach $2 billion by 2028.

A recent study in Nature Metabolism examined blood from more than 300 participants across seven cohorts and found no age‑related decline in circulating N.A.D.+ levels. Researchers could raise the molecule with supplementation, but the data challenge the premise that a universal drop drives functional aging. Lead author Riekelt Houtkooper called the findings “disappointing” for the supplement market. Longer trials are needed to assess functional impact.

Industry executives say the study will not upend sales. Andrew Shao of Niagen Bioscience, a major N.A.D.+ supplier, argued that tissue‑level declines—still documented in muscle and brain—remain the more relevant target for therapy. While the blood‑level myth may soften influencer messaging, the broader market for anti‑aging nutraceuticals is expected to stay robust as consumers chase longevity promises.