Prompted by NAC supplements controversy, U.S. lawmaker presses FDA in new letter

A U.S. congressman has requested FDA answer several questions regarding the agency’s “sudden change of policy” outlined in 2020 warning letters to dietary supplement firms marketing NAC (N-acetyl-L-cysteine) in their products.

This is at least the second letter this year from a U.S. lawmaker to FDA regarding NAC. FDA said in 2020 warning letters that NAC cannot be marketed in supplements because it was first approved as a drug in 1963, drawing criticism from the dietary supplement industry.

The ingredient has been marketed in supplements since at least the 1990s before passage of the Dietary Supplement Health and Education Act of 1994 (DSHEA), according to records submitted to FDA by the American Herbal Products Association (AHPA), as part of its support for two citizen petitions submitted by the Council for Responsible Nutrition (CRN) and Natural Products Association (NPA).

“Does the FDA believe the intent of DSHEA is to remove products that were safely on the market prior to 1994?” Rep. Jeff Duncan (R-S.C.) asked FDA Acting Commissioner Janet Woodcock in a letter dated Oct. 28.

Duncan represents a state that is home to several notable dietary supplement operations, including International Vitamin Corp.

In the four-page letter, the congressman demanded several answers pertaining to NAC, including, among other things:

Related:US senator, NPA press FDA on NAC supplements

- The number of structure/function claims and new dietary ingredient (NDI) notifications for NAC products submitted to FDA;

- How FDA reconciles inconsistencies in how it classified NAC in a review of a qualified health claim application and the 2020 warning letters; and

- The specific date FDA identified NAC as being used in the U.S. as both a drug and dietary supplement.

An FDA spokesperson said the agency has received the letter and will respond directly to the congressman.

Duncan’s letter was not limited to NAC. He also demanded answers related to whether FDA is effectively using its authority to ensure dietary supplement products entering the U.S. from places like China are safe and compliant with the law.

And while FDA is seeking new authority to require dietary supplement products be listed with the agency, Duncan noted “FDA already has access to essential information about products,” such as a Dietary Supplement Label Database maintained by the National Institutes of Health. According to several industry sources, Sen. Dick Durbin (D-Ill.) is working on draft legislation to require mandatory listing of dietary supplement products with FDA.

NAC “has been used as an ingredient in dietary supplements for three decades,” a spokesperson from Duncan’s office said in an email to Natural Products Insider. “Unfortunately, this is yet again another example of FDA inconsistently interpreting DSHEA. The industry plays a significant role in the congressman’s district, and he wants to understand why the FDA is targeting NAC while failing to address the crisis of adulterated products entering the United States from China.”

Duncan referenced, for instance, a request to FDA by Natural Alternatives International Inc. (NAI) to take enforcement action against adulterated forms of beta-alanine. This topic was the subject of a four-part series of articles by Natural Products Insider and a follow-up story reporting on FDA’s denial of NAI’s request.

“How has the FDA determined that Chinese imported beta-alanine is not only safe but not violating U.S. law?” Duncan asked Woodcock.

Dan Fabricant, president and CEO of NPA, suggested FDA’s purported failure to effectively use its current authorities is resonating with some lawmakers.

“You have an executive branch agency that is effectively going, ‘Oh no, I don’t like that part of the law. I’m not going to do anything here, but I’d really like to have some new authority.’ And I think that’s how it appears to members of Congress,” Fabricant said in an interview.

“There’s so many holes right now, and instead of addressing those holes with the authority [FDA officials] do have, they’re going to talk about new authority?” asked Fabricant, who previously oversaw FDA’s Division of Dietary Supplement Programs. “It’s bad policy flat-out, and I think lawmakers see that.”