Why Did the FDA Ban NMN — and Why Is It Legal Again?

In late 2022, the FDA notified several NMN supplement manufacturers that NMN could not be lawfully marketed as a dietary supplement in the United States. This decision caused significant confusion in the supplement market — products disappeared from some retailers, manufacturers scrambled to understand the implications, and consumers were left wondering whether the NMN they had been taking was suddenly illegal. The situation was then further complicated when, in 2023 and 2024, the FDA’s position appeared to evolve or at least became less uniformly enforced, and NMN products returned to market availability.

Understanding what actually happened — and why NMN’s regulatory status has been a moving target — requires understanding how the FDA regulates dietary supplements and a specific provision of the Dietary Supplement Health and Education Act that became the center of the dispute.

How the FDA Regulates Dietary Supplements

The United States dietary supplement market is regulated under the Dietary Supplement Health and Education Act of 1994 (DSHEA). Under DSHEA, dietary supplements occupy a regulatory category distinct from both foods and pharmaceuticals. Manufacturers do not need FDA pre-market approval to sell a supplement — unlike pharmaceuticals, which must demonstrate safety and efficacy before they can be marketed. Instead, manufacturers are responsible for ensuring their products are safe, and the FDA’s role is largely reactive — investigating safety concerns after products are on the market.

However, DSHEA includes a provision with significant implications for NMN: a compound cannot be marketed as a dietary supplement if it has been authorized for investigation as a new drug — meaning a pharmaceutical company has filed an Investigational New Drug (IND) application with the FDA for that compound — unless the supplement predated that IND authorization. The provision is designed to prevent pharmaceutical companies from first claiming a compound as a drug candidate, thereby blocking competitors from selling it as a supplement.

The MetroBiotech IND and the FDA’s 2022 Decision

MetroBiotech, a pharmaceutical company co-founded by David Sinclair and working on NMN-related compounds, filed IND applications with the FDA for NMN derivatives. The relevant question for supplement law was whether MetroBiotech’s IND applications covered NMN itself — and whether those filings predated the marketing of NMN as a dietary supplement by other companies.

In October 2022, the FDA sent warning letters to several NMN supplement manufacturers concluding that NMN did not qualify for marketing as a dietary supplement because it had been authorized for clinical investigation as a drug before being introduced into interstate commerce as a supplement. This is the “exclusion clause” in DSHEA — if a compound is first a drug candidate, it cannot later become a supplement.

The FDA’s October 2022 decision affected several manufacturers who were selling NMN as a dietary supplement, most notably removing NMN from some major retail platforms that took a conservative compliance position. ChromaDex, which sells NR (not NMN) as Tru Niagen, was not directly affected — the ruling concerned NMN specifically.

Why NMN Is Still Available: The Legal Challenge and Market Reality

The FDA’s 2022 determination was not the end of the story. Several factors kept NMN on the market and created the current ambiguous situation:

NMN manufacturers disputed the chronology. Several companies argued that NMN had been sold as a dietary supplement before MetroBiotech’s IND filings, which — if established — would exempt it from the exclusion clause under DSHEA’s “prior market” exception. Establishing the precise timeline of when NMN entered the supplement market relative to the IND filings became a contested factual question.

FDA enforcement is selective and resource-constrained. Even when the FDA concludes a product cannot lawfully be marketed, it does not automatically seize all products from the market — enforcement is prioritized based on public health risk, and a supplement with no identified safety concerns and millions of regular users does not command the same enforcement urgency as a dangerous adulterated product. Many NMN products remained available through channels that the FDA had not specifically targeted.

The regulatory dispute remained unresolved. The FDA did not issue a final, binding rule excluding NMN from the supplement category — it issued determinations in response to specific manufacturer filings. Other manufacturers who had not received warning letters continued selling NMN without a direct regulatory challenge.

Congressional and stakeholder pressure. The NMN situation attracted attention from members of Congress and the dietary supplement industry, with arguments that the FDA’s interpretation of DSHEA’s exclusion clause was overly broad and that the agency was effectively allowing pharmaceutical companies to lock supplement ingredients out of the consumer market. This political context influenced the pace and direction of regulatory action.

The Current Legal Status of NMN

As of mid-2025, the regulatory situation for NMN in the United States remains somewhat ambiguous but is practically more permissive than the October 2022 FDA letters suggested. NMN supplements are widely available from numerous manufacturers through major retail channels including Amazon, dedicated supplement retailers, and direct-to-consumer brand websites.

The FDA has not issued a final rule definitively resolving NMN’s supplement status. The agency’s position as expressed in its 2022 letters has not been formally reversed, but enforcement action has not been comprehensive. Most manufacturers selling NMN today are doing so with awareness of the regulatory history and with legal arguments available about prior market presence or the scope of the exclusion clause.

For consumers, the practical implication is that NMN supplements are purchasable and being sold without obvious legal jeopardy in most channels. The regulatory cloud does not mean the products are seized or that buying and using NMN carries legal risk for consumers — DSHEA’s provisions concern manufacturer marketing claims, not consumer use. You are not breaking any law by purchasing and using NMN.

How This Affects Product Quality Considerations

The regulatory history has a secondary effect that is practically relevant: the uncertainty created by the 2022 FDA action drove some quality manufacturers to either pause NMN sales or reformulate, while less compliance-focused producers filled the gap. The regulatory cloud that remains over NMN’s status is not a quality guarantee — manufacturers operating in ambiguous regulatory environments include both high-quality, transparent operators and opportunistic sellers with less rigorous quality standards.

The quality evaluation criteria covered in the article on how to choose an NMN supplement apply regardless of the regulatory situation. Third-party testing, certificate of analysis verification, and identified ingredient sourcing remain the primary quality signals available to consumers, independent of whether any regulatory resolution has been reached.

The Situation in Other Countries

NMN’s regulatory status varies by jurisdiction, and the US situation is not universal:

European Union: NMN is not approved as a novel food ingredient under EU food safety regulations, meaning it cannot be legally sold as a food supplement in the EU without prior authorization. Several EU countries have actively restricted NMN sales. This is a more definitive restriction than the US situation.

United Kingdom: Post-Brexit, the UK follows its own novel foods framework through the Food Standards Agency. NMN is on the UK’s novel foods list requiring authorization for sale, though enforcement has been variable.

Canada: Health Canada regulates NMN as a natural health product. NMN products with a Natural Product Number (NPN) license are legally available; unlicensed products are not. Several licensed NMN products are available through Canadian retailers.

Japan and Australia: NMN is available as a supplement in both countries, with Japan in particular being a significant NMN market given the country’s strong longevity research culture and more permissive supplement regulatory environment.

What This Means for Buyers

For US consumers, the practical guidance is straightforward: NMN supplements are available, widely used, and not subject to consumer-level legal risk. The regulatory situation is a manufacturer and retailer concern rather than a consumer concern. Buying NMN from an established brand with transparent quality practices — rather than choosing based on regulatory history — remains the most important purchasing decision.

For consumers outside the US, particularly in the EU and UK, the regulatory situation is more restrictive. If you are in one of these jurisdictions, verifying the legal status of NMN supplements in your country before purchasing from international retailers is appropriate. The regulatory restrictions are about legal marketability in those jurisdictions, not about safety determinations.

Frequently Asked Questions

Is it safe to buy NMN now, or will the FDA crack down again?

No enforcement action against consumer purchases of NMN has occurred or is contemplated — the regulatory provisions concern manufacturer marketing, not consumer use. For ongoing purchases, the risk of a sudden broad enforcement sweep that removes NMN from market availability cannot be categorically ruled out, but it has not materialized since 2022 despite the FDA’s stated position. The more likely regulatory outcome is continued ambiguity unless Congress acts to clarify DSHEA’s exclusion clause or the FDA issues a final binding rule.

Does the regulatory dispute say anything about NMN’s safety?

No. The FDA’s 2022 determination was entirely about whether NMN meets the legal definition of a dietary supplement under DSHEA’s provisions — specifically the exclusion clause related to drug investigations. It was not a safety determination. The FDA did not conclude that NMN is unsafe or harmful. The regulatory status question and the safety question are entirely separate, and the regulatory dispute does not imply a safety concern that the safety evidence does not independently support.

Should I buy NMN from US companies or international sources given the regulatory situation?

US-based manufacturers who have continued selling NMN post-2022 are doing so with legal counsel and compliance awareness, and most quality US NMN brands have maintained operations. International sources — particularly Japanese manufacturers, given Japan’s established NMN supplement market — are also viable options for quality NMN. The quality evaluation criteria (third-party testing, COA, ingredient sourcing) are more important than geography of manufacture in determining product quality.

Could NMN eventually become a prescription drug?

In theory, if MetroBiotech or another pharmaceutical company developed an NMN-based pharmaceutical that received FDA approval, they could pursue exclusive marketing rights that would prevent NMN from being sold as a supplement — the DSHEA exclusion clause in reverse, essentially. In practice, the wide availability of NMN as a generic supplement ingredient, the competitive market that has developed around it, and the political and industry pushback against pharmaceutical companies using IND filings to capture supplement ingredients all make a full pharmaceutical lock-out of NMN unlikely. This is a theoretical risk rather than an imminent practical concern.