Acetyl Cysteine
NAC was first approved as a drug in 1963 and is therefore excluded from the dietary supplement definition under the FD&C Act. FDA exercises enforcement discretion for NAC-containing supplements per the August 2022 final guidance, but NAC is not a recognized direct food additive.
What it is
N-acetyl-L-cysteine (NAC), an acetylated form of the amino acid L-cysteine, originally approved as a drug.
Used in dough conditioning (a flour-treatment agent permitted in some jurisdictions) and as a supplement ingredient. Not a typical food additive in the US.
Why it's flagged
- Excluded from US dietary supplement definition (drug-first status)
- Not authorized as a direct food additive under 21 CFR Part 172
- GI side effects at high doses
What regulators actually say
"NAC is excluded from the dietary supplement definition under the FD&C Act because NAC was approved as a new drug before it was marketed as a dietary supplement or as a food. NAC was first approved as a drug on September 14, 1963."
Regulatory status
United States — FDA
Excluded from dietary supplement definition; FDA exercises enforcement discretion for compliant NAC supplements (Final Guidance, August 2022). Not listed as a permitted food additive.
European Union — EFSA
Not authorized as a food additive under Regulation (EC) 1333/2008.
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