NR for Raising NAD+: The Strongest, Most Honestly Limited Evidence
Educational summary — not medical advice. Raising a biomarker is not the same as a proven clinical benefit; no NR trial has established a downstream functional, disease, or longevity benefit in humans. 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
This is the thread in NR's evidence base that holds up most consistently — though not without exception. Of the 8 verified human trials that measured NAD+ in some tissue, 7 found it rose — dose-dependently, across whole blood, PBMCs, skeletal muscle, and brain tissue. The one exception is Dollerup 2020's muscle substudy, which found no change in muscle NAD+ despite a drop in the NAMPT enzyme. That 7-of-8 pattern is real, replicated pharmacology, not an absolute. This page exists specifically because "raising NAD+" is the claim with the strongest trial support — every trial that also measured a downstream functional or clinical outcome found that outcome null or underpowered. Read all three parts together, not just the first one.
The mostly-consistent half: NAD+ goes up in 7 of 8 trials that measured it
Across dose (100 mg single doses to 2,000 mg/day sustained), population (healthy volunteers, obese insulin-resistant men, aged adults, heart-failure patients, newly-diagnosed Parkinson's patients), and duration (single-dose pharmacokinetics to 12 weeks), NR raised NAD+ in 7 of the 8 trials that measured it. Airhart 2017, the first human NR pharmacokinetics study, found steady-state blood NAD+ rose about 100% at the highest single dose tested, strongly correlated with circulating NR levels. Conze 2019 — ChromaDex's own manufacturer-run trial of its branded Niagen ingredient, a conflict of interest disclosed here every time this trial is cited — established a clean dose-response curve (22%/51%/142% at 100/300/1000 mg/day) sustained through 8 weeks. Martens 2018 and Wang 2022, both fully independent academic trials, confirmed the rise in PBMCs. Elhassan 2019 confirmed it directly in skeletal muscle tissue via targeted metabolomics. And NADPARK 2022 found it in brain tissue — genuinely notable, measured directly by 31P-MRS, since it implies NR-derived compounds cross into the brain and raise cerebral NAD+ there too. The one exception to this pattern is Dollerup 2020's muscle-biopsy substudy, which found NO change in muscle NAD+ despite a 14% drop in the NAMPT enzyme — the table below shows it alongside the other seven.
| Study | Tissue measured | NAD+ result | Paired functional/clinical result |
|---|---|---|---|
| Airhart 2017 PMID 29211728 | Whole blood | ~100% rise at highest single dose (p=0.001) | None measured — open-label PK study only |
| Conze 2019 PMID 31278280 | Whole blood | 22%/51%/142% dose-dependent (ChromaDex-funded) | Safety only (no flushing, no LDL/AE signal) — not a functional-outcome trial |
| Martens 2018 PMID 29599478 | PBMCs | Significant rise, 1000 mg/day | Blood pressure & arterial stiffness: NOT significant after correction, whole group |
| Dollerup 2018/2020 29992272 / 31710095 | Skeletal muscle | NO change in muscle NAD+ despite 14% NAMPT drop | Insulin sensitivity, mitochondrial respiration: both null |
| Elhassan 2019 PMID 31412242 | Skeletal muscle | Significant rise (targeted metabolomics) | Mitochondrial bioenergetics (actual respiration): unaltered |
| NADPARK 2022 PMID 35235774 | Brain tissue (cerebral, via 31P-MRS) | Significant rise | "Mild clinical improvement" — correlational, exploratory, Phase I only. Never "NR treats Parkinson's." |
| Wang 2022 PMID 36644285 | Whole blood, PBMCs | ~Doubled | 6-min walk, LVEF, quality of life: NO significant difference; authors call it underpowered |
What "raises NAD+" does and doesn't mean
Read precisely, the strongest defensible claim is: NR supplementation reliably and dose-dependently raises NAD+ across multiple human tissues, replicated by independent, non-industry-funded research groups. That's real, and it's the load-bearing finding this whole cluster is built on. It does not mean NR is a proven treatment for blood pressure, insulin resistance, muscle aging, heart failure, or Parkinson's disease — every trial in this evidence base that measured one of those downstream outcomes found it null or explicitly underpowered, despite the NAD+ rise happening right alongside it. Elhassan 2019 is a particularly clean illustration of the gap: RNA sequencing showed real transcriptomic changes in energy-metabolism genes, but actual mitochondrial respiration — the physiological output those genes are supposed to drive — stayed unchanged. A molecular signal moving is not the same as a body functioning differently.
If NAD+ elevation itself is your reason for taking NR
If raising blood NAD+ specifically — independent of a proven downstream functional benefit — is the outcome you're after, Conze 2019's dose-response data is the most direct evidence to reference: 300 mg/day produced a 51% rise, and 1,000 mg/day produced a 142% rise, both sustained through 8 weeks. See the dosage guide for how the two currently-buyable products (Tru Niagen at 300 mg, Thorne NiaCel at ~415 mg) line up against those doses, and best NR for cost per mg. Neither product is confirmed to be the exact NR source used in the independent functional trials referenced above — that connection is disclosed, not assumed, throughout this cluster.
Frequently asked questions
Does NR reliably raise NAD+?
In 7 of 8 verified trials, yes — replicated in whole blood, PBMCs, skeletal muscle, and brain tissue, at doses from 100 to 2,000 mg/day. The exception: Dollerup 2020's muscle substudy found no muscle NAD+ change.
If NAD+ goes up, does that mean NR is working?
Not automatically. Five independent trials paired a confirmed NAD+ rise with a functional/clinical measurement, and every one of those measurements came back null or underpowered.
Which tissues has NR raised NAD+ in?
Whole blood, PBMCs, skeletal muscle (in most trials — one substudy found no change), and brain tissue, measured via 31P-MRS in NADPARK.
Is raising NAD+ itself a proven health benefit?
No. It's a biomarker change with biological plausibility, not a validated clinical endpoint — no trial has proven a downstream functional benefit from it.
Related
- NR: what it is & the regulatory story
- Does NR actually do anything beyond raising NAD+? — the full null-result pattern
- NR dosage guide — the 100-2,000 mg range in context
- Best NR — ranked by cost per mg
Sources
- Airhart SE, et al. "An open-label, non-randomized study of the pharmacokinetics of nicotinamide riboside." PLoS One. 2017. PMID: 29211728
- Conze D, Brenner C, Kruger CL. "Safety and Metabolism of Long-term Administration of NIAGEN." Scientific Reports. 2019. PMID: 31278280 (ChromaDex-funded; disclosed conflict of interest.)
- Martens CR, et al. "Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+." Nature Communications. 2018. PMID: 29599478
- Dollerup OL, et al. "A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men." Am J Clin Nutr. 2018. PMID: 29992272
- Dollerup OL, et al. "Nicotinamide riboside does not alter mitochondrial respiration, content or morphology in skeletal muscle." J Physiol. 2020. PMID: 31710095
- Elhassan YS, et al. "Nicotinamide Riboside Augments the Aged Human Skeletal Muscle NAD+ Metabolome." Cell Reports. 2019. PMID: 31412242
- Brakedal B, et al. "The NADPARK study." Cell Metabolism. 2022. PMID: 35235774
- 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