FDA telegraphs enforcement strategy against NMN supplements amid NPA lawsuit

The U.S. government and Natural Products Association (NPA) are seeking a temporary pause in a court battle over the legality of a healthy aging ingredient marketed in dietary supplement products.

NPA in August filed a lawsuit, requesting a declaratory judgment that β-nicotinamide mononucleotide (NMN) should not be excluded from the definition of a dietary supplement. The U.S. Food and Drug Administration has essentially concluded the ingredient cannot be marketed in dietary supplement products because it was first authorized for investigation as a new drug.

In an Oct. 24 joint court filing, NPA, FDA and the U.S. Department of Justice (DOJ) requested a stay of the legal proceedings while FDA evaluates a citizen petition related to NMN. FDA intends to answer the citizen petition by July 31, 2025, according to the filing in the U.S. District Court for the District of Columbia.

Meanwhile, the government revealed its intent to not target NMN dietary supplements for enforcement actions under certain conditions.

“FDA has further represented to NPA that, while it considers the arguments raised in the citizen petition, the agency does not intend to prioritize enforcement action related to the sale and distribution of NMN-containing products that are labeled as dietary supplements, provided that they would be lawfully marketed dietary supplements if NMN is not excluded from the definition of a ‘dietary supplement,” attorneys for NPA and the U.S. government asserted in a joint motion to the court. But “if FDA becomes aware of new safety concerns, the agency would need to reevaluate its enforcement priorities.”

Related:FDA faces new lawsuit from NPA over anti-aging ingredient NMN

The NPA lawsuit is consequential not just for ingredient suppliers and finished product brands selling NMN. It also affects the interests of a pharmaceutical company that has been conducting clinical trials of NMN using its proprietary ingredient called MIB-626: Metro International Biotech LLC.

On the same day a stay in proceedings was requested, Metro filed a motion to intervene in the NPA lawsuit against FDA.

A substantive ruling in the lawsuit could not only determine the fate of NMN in dietary supplement products but also influence innovation in both the pharmaceutical and natural product industries. The case implicates what NPA characterized as the “drug exclusion clause” of the Dietary Supplement Health and Education Act of 1994 (DSHEA). 

This clause bars an ingredient from being marketed in a dietary supplement if it was first approved as a drug or first authorized for investigation as a new drug and the subject of “substantial clinical investigations” that have been instituted and made public. 

Related:FDA says ingredient studied as drug—β-NMN—is excluded from supplements

“Plaintiff the Natural Products Association (‘NPA’) — a trade association representing the dietary supplement industry — seeks to overturn FDA’s determination that NMN is excluded from regulation as a ‘dietary supplement’ by virtue of Metro’s study of NMN as a drug,” Metro’s lawyers wrote in a court filing. “If NPA prevails, Metro will be deprived of the protection of the preclusion clause and be at a great disadvantage compared to dietary supplement companies, undermining Metro’s substantial investments in developing NMN as a drug. Metro accordingly is entitled to intervene to safeguard its private interests.”

In March 2023, NPA and the Alliance for Natural Health filed a citizen petition with FDA.

The petition requested FDA determine NMN is not excluded from the definition of a dietary supplement or commit to exercising enforcement discretion regarding the selling of NMN as a dietary supplement. In the alternative, the petitioners requested FDA recommend that the secretary of the U.S. Department of Health and Human Services (HHS) issue a regulation finding that NMN would be lawful in supplements.