This past summer Inner Mongolia Kingdomway Pharmaceutical Limited (“Kingdom”) submitted a new dietary ingredient (NDI) notification to FDA for β-Nicotinamide Mononucleotide (NMN), a compound that has been touted for its anti-aging properties. Under the Federal Food, Drug, and Cosmetic Act, an NDI is required to market dietary supplements that contain a “new dietary ingredient,” which means a dietary ingredient that was not marketed in the US prior to October 15, 1994. (21 USC 350b (d)).

In its initial October 11, 2022, response,  FDA reiterated that the definition of dietary supplement excludes articles “authorized for investigation as a new drug … for which substantial clinical investigation have been instituted and for which the existence of such investigations have been made public,” unless the article was marketed as a food or dietary supplement prior to the authorization. (21 U.S.C. 321(ff)). And, because FDA determined that such authorization for investigation as a new drug had taken place before NMN was marketed as a food or lawfully marketed as a dietary supplement, the agency concluded that NMN is excluded from the definition of a dietary supplement. 

Last month, and in response to a letter from Kingdom’s lawyers requesting that the agency withdraw its October 11^th letter, FDA doubled down on its conclusion in a second letter which further explains the agency’s decision. Notably, in the second letter FDA:

• Indicates that it will not disclose the date on which the authorization for investigation of NMN (or any new drug) occurred unless the investigational new drug application has been publicly disclosed or acknowledged.

• Rejects the arguments that dietary ingredients marketed after January 7, 2016, the date on which NMN capsules were offered for sale in Japan, do not require an NDI notification. This argument is based on the exemption from an NDI notification for dietary ingredients which have been present in the “food supply” (21 USC 350b(a)). FDA interpreted “food supply” to include only food, and not dietary supplements. Furthermore, it found that only evidence of marketing in the U.S. was relevant.

• Reaffirms that illegal marketing of NMN without an NDI notification is not relevant to the determination of whether it is a dietary supplement (or excluded because it has already been authorized for investigation as a new drug). 

FDA previously determined that N-acetyl-L-cysteine (NAC) was excluded from the definition of a dietary supplement for similar reasons, and yet ultimately determined that enforcement discretion was appropriate. We will continue to monitor and report on developments regarding the use of NMN in dietary supplements.