UNPA NAC submission to FDA

Feb 17, 2022

Dear UNPA Colleagues:

On January 25, 2022, we submitted comments to the FDA Office of Dietary Supplement Programs, via Ms. Cara Welch, and to the Federal Docket in response to a Constituent Update titled FDA Requests Information Relevant to the Use of NAC as a Dietary Supplement. This Constituent Update was issued on November 24, 2021.

The Constituent Update specifically requested information in three areas:

  1. Information on the earliest date NAC was marketed as a dietary supplement,
  2. Information on the earliest date for NAC in a food,
  3. The safe use of NAC in products marketed in dietary supplements and any safety concerns.

For decades, NAC has been widely available. Prior to this controversy, it was sold by most major brands. During a search on Amazon in 2020 there were nearly 800 NAC dietary supplement products available.

The use of NAC in dietary supplements has been a long, ongoing project for the UNPA regulatory and compliance team. For us, the NAC saga began in early 2020 when the regulatory drumbeats started signaling a shift and industry companies began contacting us with concerns. Concerns included several brands who received FDA inquiries regarding the use of NAC in dietary supplements during FDA inspections. Some of these companies had the potential of facing regulatory action if they could not support the legal use of the ingredient. Soon after, the FDA issued Warning Letters to seven companies regarding the use of NAC triggered by health claims for the treatment of hangovers. These Warning Letters led one large electronic retailer (Amazon) to remove NAC products from their platform.

With all of this, they got the industry’s attention!

In response to these concerns and member interest, UNPA launched the NAC Working Group (NAC-WG). Participants in the NAC-WG calls included approximately 30 participating companies and individuals. Within the NAC-WG we had a subgroup of volunteers, writers, reviewers, and active participants to assist in preparation of the UNPA submission to the FDA.

Some of the UNPA members and MOU partners in the NAC Working Group include:

  • Arizona Nutritional Supplements
  • American Association of Naturopathic Physicians (AANP)
  • Bastyr University
  • FDA Compliance Simplified
  • Holistic Primary Care
  • NOW Foods
  • Ortho Molecular
  • Safety Call

These volunteers put in a tremendous effort to sift through warehouses, boxes, and basements for “old” paper records and through antiquated software systems to provide a significant collection of pre-DSHEA records. The results? Our new evidence for pre-DSHEA dietary supplement usage is substantial!

We have provided solid documentation for NAC as a pre-DSHEA ingredient and for finished dietary supplement products on the market prior to October 15, 1994. The UNPA (NAC-WG) evidence of use includes labeling (advertising, marketing, catalogs, and printed literature), manufacturing records, labels, formulas, testing documents, and invoices for interstate sales and distribution.

In addition to the information provided by UNPA member companies and collaborators, UNPA commissioned a project to audit the Townsend Letters (TL). The TL project was initiated and conducted with the financial assistance of American Association of Naturopathic Physicians (AANP) and oversight by Michael Levin, Health Business Strategies. This audit was conducted by TL staff and was supervised daily by Mr. Levin.

Townsend Letter, the Examiner of Alternative Medicine, is a well-known print magazine about alternative medicine. UNPA initiated an audit of Townsend Letter issues published between 1983-1994 to identify evidence of nutritional (dietary supplement) products containing N-acetyl-L-cysteine marketed prior to October 15, 1994.

This audit revealed thirteen advertisements for dietary supplements containing NAC pre-DSHEA. The audit results were reviewed and summarized by members Evelyn Cadman, FDA Compliance Simplified, and Daisy Herpin, UUMEP.

Regarding the FDA request for safety data, we believe safety has been well established. Longtime UNPA member, Safety Call, provided a succinct summary of the safe oral use of NAC.

Our position as of January 25, 2022:

The FDA, in attempting to exclude NAC from the dietary supplement market, is acting outside of its statutory jurisdiction and authority.

We have provided definitive evidence of pre-DSHEA use of NAC – it is an ODI. NAC is safe. There is broad agreement on this.

FDA, it appears, is using a tactic to deny ODI status to NAC by looking back, not forward from the ODI grandfathering date of October 15, 1994.  This we believe, along with others in the DS industry, is not how the ODI test is to be applied. This is a prospective provision which was included to deal with the situation of an article – DI or drug candidate being present in the market after October 15, 1994. Otherwise, the provision makes no sense.

The USP is full of botanicals that were official drugs per-DSHEA. Just to cite one example of how this provision cannot be applied prior to this date.

This is not the end of our work, the NAC-WG will pursue this important issue until we reach a proper outcome which is recognition of NAC as a lawful ODI and FDA abandons it’s misguided retro lookback policy.

A big thank you goes out to our NAC-WG volunteers! We could not have done it without you! We appreciate you!


With gratitude and looking forward to a successful outcome,

Loren Israelsen


United Natural Products Alliance

Larisa Pavlick

V.P. Regulatory and Compliance

United Natural Products Alliance