The Food and Drug Administration has four answers about N-acetyl-L-cysteine use as a dietary ingredient in the US: two answers close the door on requests to deem it lawful and the other two are maybes about a rulemaking to make it lawful and about allowing sales to continue in the interim.
All the answers announced on 31 March reach the dietary supplement industry sounding like a siren that the FDA may take the same enforcement step that it has with NAC with other ingredients long used in supplements