The pathway in one line: one step for NMN, two for NR
Both NMN and NR exist to become NAD+. They just take a different number of enzyme steps to get there.
NR is phosphorylated by NR kinases (NRKs) into NMN; the 2016 paper that mapped this found NRK1 "necessary and rate-limiting" for using NR and NMN from outside the cell. NMN is then converted into NAD+ by NMN adenylyltransferases, NMNAT1 to NMNAT3. That is two enzymatic steps: NR to NMN, then NMN to NAD+. NMN, if it reaches the inside of a cell as NMN, skips the first step and goes straight to NAD+, one step.
The criterion: count the enzymatic steps between the milligram on the label and NAD+ itself. NR: two. NMN: one, if it enters the cell as NMN rather than being broken down first. That "if" is the entire dispute in the next section.
Steps and enzyme names per Ratajczak J, et al., "NRK1 controls nicotinamide mononucleotide and nicotinamide riboside metabolism in mammalian cells," Nature Communications, 2016, PMID 27725675: "NR is initiated by phosphorylation of NR to NMN by NR kinases (NRKs)" and "NMN adenylyltransferases (NMNAT1-3) into NAD+".
Does NMN enter cells intact? Two models, stated side by side
This is the actual dispute behind "NMN works in one step": two research groups, two answers, three years apart.
Grozio, Mills, Yoshino and colleagues reported that the Slc12a8 gene "encodes a specific NMN transporter", highly expressed in the mouse small intestine: knocking Slc12a8 down "abrogates the uptake of NMN in vitro and in vivo", transport "depends on the presence of sodium ion", and reduced uptake was traced with doubly labeled isotopic NMN. Their conclusion, in their words: "the first NMN transporter".
Nature Metabolism, 2019, PMID 31131364.
Ratajczak and colleagues, using stable isotope-labelled compounds, "confirm NMN is metabolized extracellularly to NR that is then taken up by the cell and converted into NAD+", with NRK1 as the rate-limiting kinase inside. Their conclusion: mammalian cells "require conversion of extracellular NMN to NR for cellular uptake and NAD+ synthesis".
Nature Communications, 2016, PMID 27725675.
Neither model has fully closed the case
Model A was challenged in the same journal the same year: a comment by Schmidt and Brenner is titled, in full, "Absence of evidence that Slc12a8 encodes a nicotinamide mononucleotide transporter" (Nature Metabolism, 2019, PMID 32694648).
- Both models agree NAD+ can rise after NMN exposure; they disagree on whether NMN itself, or NR made from it outside the cell, crosses the membrane.
- "One-step NMN" follows only if Model A is the whole story. A real, published hypothesis, not a settled fact.
Dose-for-dose: 500 mg of each is not the same number of molecules
NMN and NR chloride are different molecules at different weights, so a milligram of one is not a milligram of the other in the count that matters: molecules delivered. NMN (β-nicotinamide mononucleotide, C11H15N2O8P) weighs 334.22 g/mol (PubChem CID 14180). Nicotinamide riboside chloride, the salt most NR supplements use, weighs 290.70 g/mol (PubChem CID 90480033).
| At 500 mg | Millimoles | Molecules delivered |
|---|---|---|
| NMN (334.22 g/mol) | 1.496 mmol | ≈ 9.01 × 1020 |
| NR chloride (290.70 g/mol) | 1.720 mmol | ≈ 1.036 × 1021 |
Run the division and 500 mg of NR chloride carries about 15% more precursor molecules than 500 mg of NMN, simply because the chloride salt is the lighter molecule per unit. This is a counting exercise, not an efficiency claim: NR still needs the extra kinase step above before it becomes the same NMN pool. It is, at minimum, a reason not to assume "500 mg" means the same thing on two different labels.
Molecular weights per PubChem compound records for nicotinamide mononucleotide (CID 14180, 334.22 g/mol) and nicotinamide riboside chloride (CID 90480033, 290.70 g/mol), read September 7, 2026. Molecule counts computed at Avogadro's number, 6.022 × 1023 per mole.
Human trial scorecard: different doses, different NAD+ rises, no head-to-head
Neither ingredient has been tested against the other in the same trial in our source material; what exists is a body of work on each, separately.
| Precursor | Published human trials, per one named source | Dose range in named sources | NAD+ change, one named trial |
|---|---|---|---|
| NMN | 10 published, per a 2023 review (Song et al., PMC10721522) | 100 to 2,000 mg/day, per the same review | Blood NAD up in every NMN group at day 30 and day 60 versus placebo and baseline, highest in the 600 mg and 900 mg groups (Yi et al., 80 healthy adults aged 40 to 65, 60 days, 300, 600 or 900 mg, PMID 36482258) |
| NR | No count printed: we found no source we could quote | 100 to 3,000 mg/day across two named trials | Whole blood NAD+ up 22%, 51% and 142% at 100, 300 and 1,000 mg within 2 weeks (Conze et al., Scientific Reports, 2019, PMID 31278280, overweight but otherwise healthy adults, 8 weeks) |
The 3,000 mg/day NR figure is a safety ceiling, not an efficacy claim: NR-SAFE, a four-week phase I trial in 20 people with Parkinson's disease, gave NR 1,500 mg twice daily and reported "no moderate or severe adverse events" and "up to 5-fold increase in blood NAD+ levels", with the authors supporting a phase II dose range "to 3000 mg per day". One honest gap on the NMN side: a 24-week trial of 250 mg/day in 14 older men with diabetes and impaired physical performance found that NMN "did not improve grip strength and walking speed"; its abstract does not report blood NAD+.
NMN trial count and dose range: Song Q, et al., Advances in Nutrition, 2023, PMC10721522 ("To date, 10 human clinical trials have been published"; "oral doses ranged from 100 mg/d to 2000 mg/d"). NMN trial: Yi L, et al., GeroScience, 2023, PMID 36482258. NR trial: Conze D, et al., Scientific Reports, 2019, PMID 31278280. NR-SAFE: Berven H, et al., Nature Communications, 2023, PMID 38016950. Grip-strength result: Akasaka H, et al., Geriatrics & Gerontology International, 2023, PMID 36443648.
Regulatory history that matters to buyers: what is on FDA's files, and when
This is the part of the comparison a lab result cannot settle: whether a US buyer could legally buy the ingredient as a supplement at all, and when.
| Date | Precursor | What happened |
|---|---|---|
| Mar 29, 2016 | NR | ChromaDex files GRAS notice GRN 635 for nicotinamide riboside chloride with FDA. |
| Aug 3, 2016 | NR | FDA's letter on GRN 635: "FDA has no questions." |
| Nov 4, 2016 | NR | Notification documents for new dietary ingredient NDI 882 (Niagen) are posted to FDA docket FDA-2015-S-0023. |
| Jul 29, 2022 | NMN | NDI 1247 for beta-NMN (SyncoZymes) is posted to docket FDA-2022-S-0023. Also in 2022, an FDA determination treats NMN as excluded from the dietary supplement definition. |
| Sep 29, 2025 | NMN | FDA "reversed course and confirmed that Beta (β) Nicotinamide Mononucleotide (NMN) is lawful for use in dietary supplements." |
| Dec 2, 2025 | NMN | FDA letter to SyncoZymes "reinstated a previous response in May 2022 that acknowledged its NDI notification"; the letter is posted to the docket on Dec 9, 2025. |
Read plainly: NR's GRAS notice drew an FDA "no questions" letter in August 2016 and its NDI notification sat on FDA's docket by November 2016, with no reversal in our source material since. NMN spent what the Natural Products Association calls "nearly three years" between a 2022 determination and the September 29, 2025 reversal. As of this page's filing date, both ingredients are sold as dietary supplements in the US, and the two NMN and two NR listings priced below were all live on September 7, 2026.
NR: FDA GRAS Notice inventory, GRN No. 635 (notifier ChromaDex, Inc.; filed Mar 29, 2016; FDA letter Aug 3, 2016; "FDA has no questions"); regulations.gov docket FDA-2015-S-0023, documents "NDI 882 - Niagen" posted Nov 4, 2016. NMN: regulations.gov docket FDA-2022-S-0023, "NDI 1247 - beta-nicotinamide mononucleotide" posted Jul 29, 2022 and the "Reinstatement response letter" posted Dec 9, 2025; Natural Products Association news posts dated September 29, 2025 and December 10, 2025 (the Sep 29 post quotes FDA's reading of the "drug preclusion" clause; the Dec 10 post calls the reversal "a reversal from a 2022 determination"). We could not open the FDA letters themselves, so no date inside them is printed here. Regulatory status can shift; treat this table as current as of the filing date above.
Price per 500 mg-equivalent in 2026: four listings, read on the date shown
We priced two NMN and two NR products on their own sites or Shopify feeds on September 7, 2026, and reduced each to a cost per 500 mg of precursor so capsule size stops hiding the comparison.
| Product | Listed price | Per 500 mg-equivalent | Read |
|---|---|---|---|
| PartiQlar Pure NMN, 500 mg/cap, 60 caps | $64.99 | $1.08 | partiqlar.com Shopify feed, Sep 7, 2026 |
| ProHealth NMN Pro 500, 500 mg per 1-capsule serving, 30 servings | $42.95 | $1.43 | prohealth.com, Sep 7, 2026 |
| Tru Niagen 300 mg NR, 30 caps | $49.00 | $2.72 | truniagen.com, Sep 7, 2026 |
| Elysium Basis, 250 mg NR per 2-capsule serving, 30 servings | $65.00 | $4.33 | elysiumhealth.com, Sep 7, 2026 |
In these four listings both NR products cost more per 500 mg-equivalent than both NMN products: $2.72 to $4.33 against $1.08 to $1.43. Four listings are not a market survey; they are the four whose price, dose and count we could read and reproduce on the same day. At 500 mg a day for 30 days, the range runs from roughly $32 to $130 a month, depending only on which of these four is chosen.
Prices read directly from each vendor's own page or Shopify feed on September 7, 2026. Per-500 mg math: PartiQlar $64.99 / 60 capsules; ProHealth $42.95 / 30 servings; Tru Niagen $49.00 / 30 capsules × (500 / 300); Elysium $65.00 / 30 servings × (500 / 250). Two further listings we had priced earlier could not be verified on the vendor's site on this date and were left out. Prices change; treat this table as a September 2026 snapshot.
The decision rule: NR, NMN, or neither
Three honest buckets, based only on what the sections above actually support.
Pick NR when
Its paperwork matters to you: an FDA "no questions" GRAS letter in 2016, an NDI notification on file the same year, and no 2022-style reversal in our source material. Expect to pay more per 500 mg-equivalent than the NMN listings above.
Pick NMN when
You want the shorter path on paper, one step instead of two, accepting that model is real but disputed. You want the lower per-500 mg price in the listings above, and a milligram claim checked against a lab certificate.
Skip both when
The purchase rides on a felt outcome rather than a lab number. The trials above report blood NAD+ and test-track endpoints; read them before expecting to feel anything, and talk to a doctor if you take medication.
Questions people also ask
Can you take NMN and NR together?
Nothing in our source material tests NMN and NR together in the same trial, so there is no combined-dose data to cite. Both feed the same NAD+ salvage pathway (NR becomes NMN via NR kinases, then NMN becomes NAD+ via NMNAT enzymes), so stacking them loads one shared pathway rather than opening a second one. Count the combined milligrams against your target dose range, and check with a doctor first.
Which raises NAD+ more, NMN or NR?
Not one number: NMN and NR have not been tested head-to-head in our source material. An 8-week trial in overweight but otherwise healthy adults found whole blood NAD+ rose 22%, 51% and 142% at 100, 300 and 1,000 mg of NR chloride within 2 weeks (Conze et al., Scientific Reports, 2019, PMID 31278280). A separate 60-day trial in 80 healthy adults aged 40 to 65 found blood NAD rose in every NMN group at 300, 600 and 900 mg, highest in the 600 mg and 900 mg groups (Yi et al., PMID 36482258). Different trials, populations and assays; read both as directional, not comparable.
Why was NMN banned and NR was not?
The two took different paths at FDA. A 2022 FDA determination treated NMN as excluded from the dietary supplement definition; on September 29, 2025, FDA reversed course and confirmed NMN is lawful for use in dietary supplements, and in a December 2, 2025 letter it reinstated a May 2022 response that had acknowledged one NMN new dietary ingredient notification, NDI 1247. NR's filings drew no such reversal in our source material: FDA answered ChromaDex's GRAS notice for nicotinamide riboside chloride, GRN 635, with 'FDA has no questions' on August 3, 2016, and the NDI 882 notification for Niagen was posted to FDA's docket on November 4, 2016.
Is NMN just a more expensive version of NR?
Not in the listings we read. Across our four September 2026 listings, cost per 500 mg-equivalent ran $1.08 to $1.43 for NMN and $2.72 to $4.33 for NR, so both NMN products came in cheaper than both NR products. Four listings are a snapshot, not a market survey; brand and capsule size move the price at least as much as the molecule does.
How we built this page
This is a chemistry-and-literature page, not a lab test of any single product. Every number on it was checked against the wording of its named source on September 7, 2026; where we could not quote a source, we printed no number.
- Molecular weights and molecule counts: PubChem compound records CID 14180 and CID 90480033.
- Enzymology and the two uptake models: three named papers, Ratajczak 2016 (PMID 27725675), Grozio 2019 (PMID 31131364) and the Schmidt and Brenner 2019 comment (PMID 32694648), cited beside each claim.
- Trial count and dose range for NMN: one named review, Song et al. 2023 (PMC10721522). NAD+ and safety results: four named trials, PMID 36482258, 31278280, 38016950 and 36443648. No trial count is printed for NR because we found no source we could quote.
- Regulatory dates: FDA's GRAS notice record for GRN 635, the regulations.gov records for NDI 882 and NDI 1247, and two Natural Products Association news posts dated September 29 and December 10, 2025. The FDA letters themselves would not open for us, so no date from inside them appears here.
- All four prices were read from each vendor's own page or Shopify feed on September 7, 2026; two listings we could not verify that day were left out rather than estimated.
- Nothing here is medical advice or a disease claim. A new supplement while pregnant, nursing, or on medication is a conversation with your doctor first.
The label where the molecule count actually gets checked
If you land on NMN after reading the comparison, the version we would actually buy is the one whose 500 mg claim was measured at 508 mg by an independent lab, and we lay out that certificate, the price math and the refund fine print in our PartiQlar Pure NMN review at /partiqlar-nmn-review/.
Everything above treats a milligram as a number to check, not trust. That review is where we ran the check on one bottle instead of a molecule in the abstract.
Read the certificate before the price. PartiQlar's independent lab certificate (Certified Laboratories, sample received Nov 4, 2025) measured 508 mg of NMN per capsule against a 500 mg label claim, so that panel had already cleared its own check.
Do the per-500 mg math on any bottle. At $64.99 for 60 capsules, PartiQlar runs $1.08 per capsule, the lowest per 500 mg-equivalent of the four listings priced above.
Affiliate disclosure: the review linked above contains affiliate links, and a purchase made through them may earn us a commission at no extra cost to you. This page carries no affiliate link of its own.