Supplement Quality Control

Supplement quality is repeatedly tied to purity, testing, delivery, and supply-chain integrity. The article claims that many tested Amazon NMN products did not contain the claimed amount and some contained no NMN. Reliable suppliers are described as having been found only after many candidates were tested. Amazon is criticized as a marketplace where supplements may be mislabeled, underdosed, counterfeit, or substituted. Overseas raw materials are described as potential sources of heavy metals or impurities. The article favors buying directly from reputable manufacturers and checking for lab testing.