A clinical-stage pharmaceutical company that has been investigating the use of nicotinamide mononucleotide (NMN) to treat medical conditions, including Alzheimer’s, has requested the Food and Drug Administration uphold its determination that the ingredient is excluded from the definition of a dietary supplement product and cannot be marketed in such products.

Metro International Biotech LLC (Metro) in November wrote a 12-page letter to FDA, in response to a citizen petition filed in 2023 by the Alliance for Natural Health USA (ANH) and Natural Products Association (NPA). The citizen petition requested FDA reverse its position that a popular anti-aging ingredient, NMN, is excluded from the definition of a dietary supplement.

The pharma company agreed with FDA that NMN is properly barred from being marketed as a dietary supplement under the so-called drug exclusion clause of the Federal Food, Drug & Cosmetic Act (FDCA).

“The FDA should not permit NMN products to be sold as a dietary supplement, which would be in violation of the drug exclusion clause and without sufficient demonstration of safety, adequate directions for use, or compliance with good manufacturing practices,” Metro concluded in the Nov. 20 letter.

Metro is researching NMN as a new drug and said it has commenced substantial clinical investigations under an investigational new drug application (IND) to treat certain medical conditions, including Alzheimer’s, Friedreich ataxia and kidney disease.

Related:FDA sticking to its guns on NMN in dietary supplements

FDA has concluded NMN was authorized for investigation as a new drug and is the subject of substantial clinical investigations that have been instituted and made public, prior to being lawfully marketed as a dietary supplement product.

FDA has not yet substantively responded to the petition filed by ANH and NPA. In late August, the agency sent an interim response to the groups, saying it could not reach a decision on the petition within 180 days as a result of “competing agency priorities.”

FDA sent a similar interim response letter in November to the Council for Responsible Nutrition (CRN), in response to a petition it filed concerning FDA’s interpretation of the drug exclusion clause.

Dan Fabricant, president and CEO of NPA, said Metro’s comments make “it clear” there must “be a fix” to the drug exclusion clause in the FDCA “through one of the three branches of government.”

If Metro’s interpretations of the law are implemented by FDA, “there is no space or protection for dietary supplements or foods looking to play a role in health and wellness, only drugs going forward,” Fabricant told Natural Products Insider. “The very act of submitting an IND for a trial on a supplement or food, which many universities and their IRBs [institutional review boards] require, even for structure/function or kinetic endpoints, would exclude one from the market indefinitely as a supplement or food. I know it’s winter, but that’s an ice age on innovation, not a chill. We look forward to continued collaboration with ANH on a path forward.”

ANH Executive and Scientific Director Rob Verkerk said his organization concurred with NPA's assessment.

"There needs to be a fix for the drug preclusion clause that works against wider, low-cost access to highly effective dietary supplements like NMN," he said in an email. "We can't let pharmaceutical companies keep gaining monopolies on vital, natural ingredients Americans need to improve their health."