Washington, D.C.—The Council for Responsible Nutrition (CRN) has expressed disappointment with FDA’s response to its citizen petition about the status of N-acetyl-L-cysteine (NAC) as a legal dietary supplement.

The petition,as WholeFoods previously reported,was filed in June 2021 following several meetings with FDA leadership. While NAC has been marketed as a dietary supplements for decades with FDA’s knowledge, in July 2020 FDA issued warning letters asserting the product was previously approved as a drug, and therefore is not a supplement, a policy change which CRN feels is legally invalid on multiple grounds. The records for NAC drug approval contain unreliable information; NAC drugs approved prior to 2016 appear to contain different forms of NAC from that used in supplements; the policy change is retroactive, violating the legal presumption against statutory retroactivity; and the delay between sales of NAC supplements and FDA’s warning letters was unreasonably long, violating the equitable defense of laches.

The tentative response from FDA, delivered November 24, states that “we are currently considering the issues raised by your citizen petition along with the other information filed in the docket, and that we have not reached a decision on your petition because of the complex nature of your request and research that we are still working to complete.”

The response also notes that CRN’s citizen petition is being evaluated concurrently with asimilar citizen petition from the Natural Products Association(NPA), in which NPA requests that either FDA determine that NAC is not excluded from the definition of a dietary supplement or recommend to the Secretary of HHS that they issue a regulation finding that NAC would be lawful under the FDCA.

In the meantime, FDA is open to receiving information on the earliest date that NAC was marketed as a supplement or as a food, in order to help it evaluate CRN’s request. Looking to NPA’s petition, FDA is asking that interested parties submit information to NPA docket FDA-2021-P-0938 regarding safety data for NAC. The full response, as well as details regarding the data FDA is requesting, can be found here.

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CRN’s President and CEO Steve Mister expressed dissatisfaction in a press release, stating: “The legal issues here are clear: The provisions of the Dietary Supplement Health and Education Act of 1994 (DSHEA) may not be interpreted retroactively to remove ingredients that were lawfully marketed in 1994 and have enjoyed a long history of safe use since then. The delay in clearing up the status of NAC by asking for more data and refusing to admit its error disregards the law and disserves consumers who use NAC.

“This is not a complicated determination for FDA to make,” Mister continued. “DSHEA makes clear that ingredients in use as dietary supplement ingredients prior to its enactment are grandfathered into the supplement marketplace. Thus, pharmaceutical manufacturers could not have had any expectation of exclusivity in the years prior to the creation of this provision of the law. Given the long history of safe use of NAC, FDA cannot now try to establish a safety concern in order to award this ingredient exclusively to drug makers. EvenmembersofCongresshave expressed concerns over FDA’s position on NAC while the agency continues to avoid admitting its error in the warning letters.

“As FDA unduly prolongs making clear NAC’s status, many retailers have discontinued selling supplements containing NAC in misplaced reliance on those warning letters, which means consumers have a difficult time locating these products,” Mister concluded. “FDA’s delay is a disservice to the dietary supplement industry, retailers, health care practitioners, and most importantly, the more than 200 million supplement users who rely on FDA to do its job.”