Benefits
Documented blood NAD+ elevation
In placebo-controlled trials of Niagen, whole-blood NAD+ rose 22%, 51% and 142% at 100, 300 and 1,000 mg a day over 8 weeks, and NAD+ in blood immune cells rose about 60% at 1,000 mg a day in older adults. A small open-label study, and a 14-day randomized trial by Nestle researchers with no ChromaDex authors, each saw whole-blood NAD+ about double. These are blood markers, not measured health benefits.
Oxidative stress markers in two trials
In a 6-week crossover pilot in 25 adults with moderate to severe kidney disease, Niagen 1,000 mg a day lowered F2-isoprostanes, a marker of oxidative damage, versus placebo (a secondary outcome). In 12 older men, a single NR dose lowered F2-isoprostanes by 18% two hours later, with no change in 12 young men. Both are small studies of markers.
Cardiovascular markers in older adults
In a 6-week crossover trial in 30 healthy adults aged 55 to 79, Niagen 1,000 mg a day was well tolerated. Systolic blood pressure was 9 mmHg lower in a post-hoc subgroup with elevated or stage 1 high blood pressure, but the authors say no statistical inference can be made from that exploratory analysis. No cardiovascular outcome has been tested.
Insulin sensitivity and muscle mitochondria unchanged in trials
In a 6-week crossover trial in 13 overweight or obese adults, Niagen 1,000 mg a day raised muscle NAD+ metabolites but did not change insulin sensitivity, mitochondrial function or blood pressure. A 12-week trial of NR at 2,000 mg a day in 40 obese men also found no change in insulin sensitivity or muscle mitochondria.
Tolerability in controlled trials
Niagen was well tolerated at up to 1,000 mg a day for 8 weeks, with adverse events like placebo and no flushing, and NR at 2,000 mg a day for 12 weeks caused no serious adverse events in obese men. EFSA judged NR chloride safe in supplements at up to 300 mg a day for healthy adults and up to 230 mg a day in pregnancy and breastfeeding.
Mechanism of action
Direct NAD+ precursor pathway
NR is converted by NR kinase enzymes to NMN and then to NAD+. In mice, oral NR raised liver NAD+ more than nicotinic acid or nicotinamide, and in people single doses raised the blood NAD+ metabolome in a dose-dependent way.
Sirtuin and PARP substrate supply
NAD+ is consumed by sirtuins, which influence gene expression and protein activity, and by PARP enzymes, which signal DNA damage. Raising NAD+ supplies these enzymes, but no trial cited here measured sirtuin or PARP activity after Niagen, and no aging outcome has been tested.
Clinical trials
Randomized, double-blind, placebo-controlled parallel trial: Niagen 100, 300 or 1,000 mg a day or placebo for 8 weeks. Funded by ChromaDex. (Conze et al. 2019, Sci Rep)
140 overweight but otherwise healthy adults (35 per group)
Whole-blood NAD+ rose 22%, 51% and 142% at the three doses and stayed up. There were no reports of flushing, adverse events did not differ from placebo, and LDL cholesterol did not rise. No health outcome was tested.
Randomized, double-blind, placebo-controlled crossover trial: Niagen 500 mg twice daily or placebo for 6 weeks each. ChromaDex supplied the pills and part of the funding. (Martens et al. 2018, Nat Commun)
30 healthy adults aged 55 to 79
NAD+ in blood immune cells rose about 60% and the supplement was well tolerated. Systolic blood pressure was 9 mmHg lower in a post-hoc subgroup with elevated or stage 1 high blood pressure, but the authors say no statistical inference can be drawn from this exploratory analysis.
Non-randomized, open-label study: Niagen 250 mg on days 1 and 2, raised step by step to 1,000 mg twice daily on days 7 and 8, then 24 hours of blood sampling after a 1,000 mg dose on day 9. (Airhart et al. 2017, PLoS One)
8 healthy volunteers
Whole-blood NAD+ rose 100% at steady state (p=0.001), and NR was well tolerated with no adverse events. There was no placebo group, and no health outcome was measured.
Randomized, double-blind, placebo-controlled crossover trial: Niagen 1,000 mg a day or placebo for 6 weeks each, with clamp tests, muscle biopsies and scans. ChromaDex supplied the capsules. (Remie et al. 2020, Am J Clin Nutr)
13 healthy overweight or obese men and women
Muscle NAD+ metabolites rose, and fat-free mass and sleeping metabolic rate rose slightly. Insulin sensitivity, mitochondrial function, liver fat, blood pressure, inflammation markers and energy metabolism did not change.
Pilot randomized, double-blind, placebo-controlled crossover trial comparing Niagen 1,000 mg a day, coenzyme Q10 1,200 mg a day and placebo, 6 weeks each; oxidative stress and inflammation markers were prespecified secondary outcomes. (Ahmadi et al. 2025, Clin J Am Soc Nephrol)
25 adults with moderate to severe chronic kidney disease (mean age 61)
Compared with placebo, Niagen lowered five-series F2-isoprostanes, a marker of oxidative damage (P<0.05), raised plasma IL-2 and improved a bioenergetic index in monocytes. These are blood markers in a small pilot.
Double-blind crossover study: one dose of NR or placebo, with blood and urine sampled before and 2 hours after, then exercise tests. (Dolopikou et al. 2020, Eur J Nutr)
12 young and 12 older men
NR raised red-cell NADH and NADPH in both groups. In the older men only, F2-isoprostanes fell 18% and glutathione tended to rise; isometric torque improved 8% and a fatigue index 15%. NR had no effect in the young men.
Investigator-initiated, randomized, double-blind, placebo-controlled parallel trial: NR 1,000 mg twice daily or placebo for 12 weeks. (Dollerup et al. 2018, Am J Clin Nutr)
40 sedentary obese, insulin-resistant men aged 40 to 70
Insulin sensitivity, glucose metabolism, resting energy expenditure, fat burning and body composition did not improve. There were no serious adverse events and safety blood tests were normal.
Randomized, open-label, placebo-controlled four-arm parallel trial at Nestle Research in Lausanne: Tru Niagen Pro nicotinamide riboside 1,000 mg, NMN 1,000 mg, nicotinamide 500 mg or placebo once daily for 14 days. The authors worked for Nestle or Cryptobiotix, not ChromaDex. (Christen et al. 2026, Nat Metab)
65 healthy adults analyzed (32 men, 33 women; mean age 34.7 years), 16 of them in the NR group.
Whole-blood NAD+, the primary outcome, roughly doubled with NR versus placebo (difference 49.4 µM, 95% CI 39.5 to 59.3, P<0.001), similar to NMN, while nicotinamide had no lasting effect (P=0.461). NADH, NADP+ and NADPH did not change. All products were well tolerated; one NR participant had low blood pressure judged probably related. The trial was open-label and measured blood markers only.