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★★☆Single study — solid evidence, such as one good trial or a large observational dataset, but not replicated at the top tier.
Sublingual NMN got no further than the swallowed kind
Fourteen men took a single dose each way with blood drawn over the next hour. NMN, nicotinamide and NAD came out the same either way.
What the study found
Under the tongue delivered no more NMN than swallowing it
Sublingual NMN is sold on the claim that it slips past the liver. Fourteen men took a single dose each way with blood drawn over the next hour, and NMN, nicotinamide and NAD came out the same either way. Only 2PY and 4PY, the terminal breakdown products, rose faster.
The caveat · Says nothing about daily use
Fourteen men, one dose each, and sixty minutes of blood sampling, so this describes the first hour and nothing about daily use or any outcome. The authors could not say where the extra 2PY and 4PY came from. All three work for Meiji Holdings, which sells NMN.