NR Dosage: How Much Do the Trials Actually Use (100mg–2,000mg)?
Educational summary — not medical advice. NR has no established RDA or upper limit, and no human trial has run past 12 weeks at any dose. This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.
The honest answer
Human trials used 100–2000 mg/day. 300 mg is Conze 2019's dose-response mid arm (a 51% NAD+ increase); most functional/mechanistic trials (Martens, Elhassan, NADPARK) standardized on 1000 mg/day; two trials in more clinically burdened populations used 2000 mg/day. The retail flagship, Tru Niagen, ships at 300 mg — meaningfully below the 1000 mg dose most functional trials tested. There's no RDA or upper limit because NR isn't treated as an essential nutrient, and no human trial has run past 12 weeks at any dose.
The dose depends on which trial's evidence you're chasing
NR's clearest dose-response data comes from a single trial: Conze 2019, an 8-week RCT dosing 100, 300, and 1,000 mg/day, found whole-blood NAD+ rose dose-dependently — 22%, 51%, and 142% respectively — and stayed elevated through week 8. This is ChromaDex's own manufacturer-run trial of its own branded Niagen ingredient (Conze and Kruger are ChromaDex scientists; Brenner is a ChromaDex science advisor and NR patent co-holder) — a real conflict of interest, disclosed here every time this trial is cited, though the dose-response shape itself is a straightforward pharmacokinetic finding, not an efficacy claim.
Once you move past dose-response into the trials that measured a functional or clinical outcome, the dose clusters at 1000 mg/day: Martens 2018 (500 mg BID, cardiovascular), Elhassan 2019 (muscle mitochondria), and NADPARK 2022 (cerebral NAD+ in Parkinson's patients) all used it. Two trials in more clinically burdened populations pushed to 2000 mg/day (1,000 mg BID): Dollerup 2018 and its 2020 muscle-biopsy companion in obese, insulin-resistant men, and Wang 2022 in heart-failure patients. Read the results at each dose carefully before assuming higher is better — every one of these functional-outcome trials found NAD+ rose but the clinical/functional measure stayed null or underpowered; see the full breakdown.
| Use case | Dose studied | Result |
|---|---|---|
| Dose-response anchor | 100/300/1000 mg/day, 8 weeks | NAD+ up 22%/51%/142%; no flushing; no LDL or AE signal (Conze 2019, ChromaDex-funded) |
| Most-used functional-trial dose | 1000 mg/day, 21 days-6 weeks | NAD+ up in muscle (Elhassan) and brain tissue (NADPARK); blood pressure/arterial stiffness (Martens) and muscle bioenergetics (Elhassan) both null on the functional measure |
| High-dose, clinically burdened populations | 2000 mg/day, 12 weeks | Safe and tolerated; insulin sensitivity (Dollerup) and heart-failure walk distance/EF (Wang) both null; Wang's authors call the trial underpowered |
| Retail flagship dose | 300 mg/day (Tru Niagen) | Matches Conze's mid dose-response arm exactly; below the 1,000 mg dose most functional trials used |
Dose checker: how much NR are you actually taking?
Enter the NR milligrams per serving from your label (look for "Nicotinamide Riboside ___ mg" on the Supplement Facts panel) and how many servings you take per day.
How to think about the dose you're actually taking
- 300 mg/day is a real, trial-matched dose for raising NAD+ — it's Conze 2019's exact mid dose-response arm, and it's what Tru Niagen ships at. It is not the dose most functional-outcome trials used.
- 1000 mg/day is where the functional/mechanistic trial evidence actually lives — Martens, Elhassan, and NADPARK all standardized here. Neither live product on this site matches it exactly; Thorne NiaCel's ~415 mg is closer but still under it.
- 2000 mg/day has only been tested in two 12-week trials, both in clinically burdened populations (obesity/insulin resistance, heart failure) — and both found the functional endpoint null. Don't treat it as a "stronger" dose without also weighing that null result.
- No trial has run past 12 weeks. There is no long-term (6-month+) human safety data at any NR dose.
- Pregnant or breastfeeding? There is no data at all for NR in this population — check with a clinician, because of the total absence of data, not a specific toxicity signal.
Picks by dose
Full comparison, including the ChromaDex/Thorne litigation context, is on best NR.
Niagen-branded; matches Conze 2019's mid arm (51% NAD+ increase) exactly, but below the 1000 mg functional-trial dose.
NSF Certified for Sport; Thorne's own NR hydrogen malate form, not Niagen. Still below the 1000 mg dose most functional trials used.
As an Amazon Associate we earn from qualifying purchases. Of 2 products live-verified; ranked by disclosed mg, never commissions.
Frequently asked questions
How much NR should I take per day?
Conze 2019 established 100/300/1000 mg dose-response. Most functional trials used 1000 mg/day; two used 2000 mg/day. No RDA or UL exists.
Is Tru Niagen's 300mg dose enough?
It matches Conze's mid dose-response arm for raising NAD+, but is below the 1000 mg dose most functional-outcome trials tested.
Is 2,000mg/day of NR safe?
Tolerated with no serious adverse events in the two 12-week trials that tested it. Short-term-tested only — no trial has run longer.
Is there an NR RDA or upper limit?
No. NR isn't treated as an essential nutrient, so no RDA or official UL exists. Conze 2019 only supports "the development of" a future UL.
Related
- NR: what it is & the regulatory story
- Best NR — Tru Niagen vs. Thorne NiaCel, ranked by cost per mg
- NR for raising NAD+
- Does NR actually do anything beyond raising NAD+?
Sources
- Conze D, Brenner C, Kruger CL. "Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride)." Scientific Reports. 2019. PMID: 31278280 (100/300/1000 mg/day; ChromaDex-funded.)
- Martens CR, et al. "Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults." Nature Communications. 2018. PMID: 29599478 (1000 mg/day.)
- Elhassan YS, et al. "Nicotinamide Riboside Augments the Aged Human Skeletal Muscle NAD+ Metabolome." Cell Reports. 2019. PMID: 31412242 (1000 mg/day.)
- Brakedal B, et al. "The NADPARK study." Cell Metabolism. 2022. PMID: 35235774 (1000 mg/day.)
- Dollerup OL, et al. "A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men." Am J Clin Nutr. 2018. PMID: 29992272 (2000 mg/day.)
- Wang DD, et al. "Safety and Tolerability of Nicotinamide Riboside in Heart Failure With Reduced Ejection Fraction." JACC: Basic to Translational Science. 2022. PMID: 36644285 (2000 mg/day.)
- Full product dataset: /nr/cost-by-brand.json (CC BY 4.0).