Washington, D.C.—In July 2020, the U.S. Food and Drug Administration (FDA) sent warning letters to seven supplement companies selling products containing N-acetyl-L-cysteine (NAC), claiming  that NAC was not lawful for sale as an ingredient in a dietary supplement because NAC had already been approved as a drug prior (in 1963) to such supplement sales. Since July of 2020, industry associations—including theCouncil for Responsible Nutrition (CRN),  theNatural Products Association (NPA), theAmerican Herbal Products Association (AHPA)and theUnited Natural Products Alliance (UNPA)—as well as legal experts including WholeFoods Magazine Legal Editor Scott C. Tips, have been working to clarify that NAC is a lawful dietary ingredient.

On March 31, 2022, the FDA announced that it has denied the request in citizen petitions from theCRNand the NPAthat asked the agency to determine that products containing NAC are not excluded from the definition of a dietary supplement.

In aresponse sent to CRN and NPA, Douglas Stearn, Deputy Director for Regulatory Affairs, Center for Food Safety and Applied Nutrition, wrote: "FDA is denying the CRN Petition in its entirety and the NPA Petition’s request that FDA reverse our position that products containing NAC are excluded from the definition of dietary supplement under the exclusion clause." Stearn explained FDA's stance that NAC was approved as a new drug in 1963, and said the petition failed to document a history of NAC having been marketed as a dietary supplement before that date.

FDA said NPA citizen petition’s alternative request that the agency undertake rulemaking to allow the use of NAC in dietary supplements remains under review, along with additional information submitted to the docket in response to the agency'srequest for information.

Stearn acknowledged that FDA's review thus far has not identified safety concerns with respect to the use of NAC in or as a dietary supplement, and said the agency is considering initiating rulemaking to permit the use of NAC in or as a dietary supplement. He concluded: "If, among other considerations, FDA does not identify safety concerns as we continue our review of the available data and information, we are likely to propose a rule providing that NAC is not excluded from the definition of dietary supplement. In the interim, while we work to complete our review, for the reasons stated above, we think it appropriate to consider exercising enforcement discretion with respect to products labeled as dietary supplements that contain NAC if such products would be lawfully marketed dietary supplements if NAC were not excluded from the definition of dietary supplement and are not otherwise in violation of the FD&C Act."

In a Constituent Updateissued on March 31, 2022, FDA said it intends to issue guidance about its policy on NAC-containing products labeled as dietary supplements "in the near future."

Prior to this new move by FDA, NPA had already filed a lawsuitagainst the agency, requesting that FDA “cease its unlawful retroactive application of the Food, Drug, and Cosmetic Act” against NAC. As WholeFoods Magazine previously reported, Daniel Fabricant, Ph.D., President and CEO of NPA, has said, “We are very concerned that a safe, legal natural product that has been sold for over 30 years is under what appears to be a regulatory sneak attack by the FDA, and even more concerned if this illegal approach may be used for other ingredients."

CRN echoed those concerns in a statement dismissing FDA's latest action. CRN President & CEO Steve Mister said, “Even though FDA has previously acknowledged NAC as a legal and safe supplement ingredient, the agency is attempting to create the power to remove legitimate dietary supplements from the market that the law plainly does not give it."

This, CRN cautioned, "sets dangerous precedent that FDA may take other dietary ingredients off the table as well." Mister explained, "While the ingredient at issue now is NAC, a broader issue is at stake—FDA’s ability to declare tried and true dietary ingredients off limits to dietary supplements and to confer drug companies with a monopoly over those ingredients, with few options for industry to challenge those actions. FDA claims to have this authority regardless of whether the dietary ingredient under review is marketed for the same intended uses, in the same delivery forms, or the same dosage as the drug. Today’s decision sets a dangerous and extralegal precedent for other supplement ingredients.

“Further, FDA’s announcement today that it may launch a rulemaking specific to NAC in the future could conceivably take years to accomplish, making this situation far more challenging and untenable for the industry, retailers, and consumers—leaving this safe, legal, and beneficial ingredient in a state of regulatory limbo."

Mister added that CRN welcomes FDA's indication that it plans to exercise enforcement discretion for otherwise lawfully marketed dietary supplements containing NAC.

"We are guardedly hopeful this announcement gives retailers the assurance they need to continue providing NAC products to consumers," Mister said. "CRN is also encouraged that FDA recognizes there are no safety issues with respect to NAC’s long history of use; however, enforcement discretion and a vague promise of future rulemaking do not provide industry and consumers adequate assurances of future access to this ingredient.

“CRN also acknowledges that FDA has made clear its decision on NAC is now a final agency action, ripe for judicial interpretation. We are pleased to get this finality and clarity, while we respectfully disagree with the agency’s analysis, so CRN and our members can evaluate our options going forward. We are presently in consultation with our members about next steps, but every option—including immediate legal action—remains on the table.”
Background: CRN Files Citizen Petition with FDA over NAC Legal Status NPA Sues FDA: Asks Courts to “Block Unlawful Action in NAC Situation” AHPA to FDA: Clarify that NAC is a Lawful Dietary Ingredient Associations Submit Comments on FDA’s Tentative Response to NAC Petitions UNPA Submits Proof of NAC Pre-DSHEA Sale to FDA