Washington, D.C.—The Council for Responsible Nutrition (CRN) has shared an update on FDA’s position on N-acetyl-L-cysteine (NAC) supplements, namely: Retailers shouldn’t act prematurely.

In July, CRN states, FDA sent out warning letters informing companies that the FDCA prohibits companies from marketing products containing NAC as dietary supplements because the ingredient was first approved as a drug.

CRN challenged this position in a letter sent to FDA in December, noting concerns about the reliability of decades-old NAC drug approval records; suggesting that FDA’s past conduct towards NAC bars this “sudden and drastic change in practice,” a reference to the fact thatFDA has considered dozens of structure-function claims for NAC without objection;and questioning the legality of FDA’s interpretation of the drug preclusion provision of the FDCA as being retroactive—in other words: Given that NAC has been marketed as a dietary supplement for years without FDA action, and noting FDA’s previous approval of structure/function claims for supplements containing NAC, can FDA now reverse those decisions due to the drug preclusion provision?

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On May 6,FDA sent a responseto CRN stating: “We are closely reviewing the information provided in your letter and will provide a more substantive response once our evaluation is complete.”

Based on this statement, CRN is letting retailers know that limiting the sale of NAC based on the July 2020 warning letters may be premature, calling the issue “far from settled.”

CRN is awaiting a more detailed response.