The rule the bill would put a clock on is written and enforced here.
U.S. Food and Drug AdministrationPublic domain
Illustrative of the agency whose rule the bill targets. Not a photograph connected to the bill's introduction.
A Bill in Congress Could Put an Expiry Date on the Rule That Killed NMN and NAC
If you have ever wondered why NAC disappeared from supplement shelves, or why NMN is sold almost everywhere except the United States, the answer sits inside one paragraph of a 1994 law that almost nobody outside the industry has heard of.
- Rep. Diana Harshbarger has introduced the Dietary Supplement Innovation Act, a bill that would rewrite the FDA rule known as drug preclusion, the rule that pulled NMN, NAC and CBD out of the supplement market.
- Preclusion says that if an ingredient was ever put into a drug filing before it was sold as a supplement, it can be blocked forever, even if the drug program was abandoned years ago, and the FDA does not disclose which filings trigger it.
- The bill would let preclusion expire after seven years of abandoned drug development, raise the trigger to Phase 2 and Phase 3 trials only, protect anything sold before October 1994, and let a company challenge an FDA preclusion claim in court with the burden of proof on the agency.
- This is an introduced bill, not a law, and most bills die quietly. One of the original architects of the 1994 law this bill would amend says it aims at the wrong section and covers only a tiny slice of the real problem.
The paragraph that quietly emptied a shelf
The provision is called drug preclusion, and the logic behind it is simple to state and brutal in practice. If an ingredient was ever approved as a drug, or even just put into an investigational drug filing, before it was sold as a supplement, it can never legally be a supplement, full stop. Two details make this worse than it sounds. First, the FDA does not disclose the date or contents of an investigational new drug application, so a company can be blocked by a filing it has no way to see coming. Second, preclusion never expires on its own. Even if the drug program behind the filing was abandoned a decade ago and nothing ever reached a pharmacy shelf, the supplement door stays shut forever. That single mechanism is why NAC, a long time supplement staple, vanished from United States shelves, and why NMN is sold openly almost everywhere except here.
why NAC, a long time supplement staple, vanished from United States shelves, and why NMN is sold openly almost everywhere except here
What the new bill would actually change
Rep. Diana Harshbarger has introduced the Dietary Supplement Innovation Act to rewrite that provision. It attacks the problem from five directions at once. A grandfather clause protects any substance marketed in food or supplements before October 15, 1994. An abandonment clock lets preclusion lapse once drug development has sat inactive or withdrawn for at least seven straight years. The trigger itself gets raised, so only Phase 2 and Phase 3 trials count rather than any early stage research. The FDA would have to weigh route of administration, dosage, concentration and relative safety before calling a drug and a supplement the same article. And an FDA warning asserting a preclusion violation would become immediately reviewable in court, with the burden of proof placed on the agency rather than the company. The three major supplement trade groups, CHPA, AHPA and CRN, all endorsed the bill within a day of its introduction.
Honest caveat
This is an introduced bill, not a law. It has not passed a committee, let alone either chamber of Congress, and the overwhelming base rate for introduced bills is that they die quietly. Three of the four sources behind this story are interested parties, the bill's own sponsor and three trade associations that have lobbied on this issue for years, so their enthusiasm is not evidence of the bill's merits on its own. The sharpest critic found in reporting on this bill is not an outsider either. Scott Bass, principal at Scott Bass Life Sciences and one of the original architects of the 1994 law this bill would amend, argues it targets the wrong section of the statute entirely and addresses only a tiny slice of the real bottleneck facing new supplement ingredients. No bill number was retrievable at the time of writing, and the exact introduction date is reported inconsistently across sources as either September 9 or September 10.
What this means for you
Do not expect NMN or NAC back on United States shelves anytime soon because of this alone. What changed today is that, for the first time, a bill exists that would put a clock on a rule that previously had none, and it arrived with support from every major trade group in the industry. If you already buy NMN from an international source, nothing about the legal picture has changed yet. The thing worth doing is watching Congress.gov for a bill number and a committee referral, since that is the next real signal, not this introduction itself.
Primary sources
- Harshbarger Introduces Legislation to Fix Outdated FDA Drug Preclusion Rules. Office of Rep. Diana Harshbarger, September 10, 2026.
- Dietary Supplement Trades Applaud Legislation to Modernize Drug Preclusion Framework. CRN, CHPA and AHPA joint statement, September 9, 2026.
- New bill seeks to fix drug preclusion provision to boost dietary supplement innovation. NutraIngredients, September 12, 2026.
Common questions
What is drug preclusion?
Drug preclusion is a provision of the 1994 law that governs supplements. It says that if an ingredient was ever put into an investigational drug filing before it was sold as a supplement, it can never legally be a supplement again, even if the drug program was abandoned years later and nothing ever reached a pharmacy. The FDA does not publish which filings trigger this, so a company can be blocked by paperwork it has no way to see in advance.
Does this bill mean NMN and NAC are coming back to United States shelves?
Not yet, and possibly not at all. This is a bill that has just been introduced in Congress, and the overwhelming majority of introduced bills never become law. It has not passed a committee or either chamber. The honest headline is that a bill exists and three major supplement trade groups support it, not that anything on shelves has changed.
Why is a DSHEA insider critical of a bill that would help supplements?
Scott Bass, one of the original architects of the 1994 law this bill would amend, argues the fix targets the wrong section of the statute and addresses what he calls only a tiny slice of the real problem with how new supplement ingredients get approved. His critique is a reminder that industry enthusiasm for a bill is not the same thing as expert agreement that it solves the actual issue.
Stay Curious.
Better health isn't found in a single article. It's built through curiosity, evidence, and small discoveries over time. Join thousands exploring longevity, gut health, recovery, nutrition, and the tools that truly make a difference.