NAD+ Supplements

What it is

Nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are vitamin B3-related compounds sold as capsules and powders. The body uses them to make NAD+ (nicotinamide adenine dinucleotide), a coenzyme involved in energy metabolism and DNA repair that tends to fall with age [1]. Trials have used 250 to 3,000 mg a day for 2 to 48 weeks [2]. Wellness clinics also sell injected NAD+ drips, but no proper trial has tested injected NAD+ for anti-aging or wellness outcomes [1].

How it might work

NAD+ is required for mitochondrial energy production, which is the proposed reason NR and NMN might help with fatigue and aging [2]. In a 2026 head-to-head trial, NR and NMN raised whole-blood NAD+, probably after gut bacteria converted part of the dose into nicotinic acid (the Preiss–Handler pathway) [3].

What the research says

Blood NAD+. In an 8-week trial of 140 adults with overweight, 100, 300 and 1,000 mg a day of NR raised whole-blood NAD+ by 22%, 51% and 142% [4]. A 2026 head-to-head trial in 65 healthy adults found 1 g a day of NR or NMN raised whole-blood NAD+ about two-fold over 14 days, while 0.5 g of nicotinamide did not [3]. An 80-person, 60-day trial found NMN raised blood NAD+ at all doses tested (300, 600 and 900 mg a day) [5], a 12-week trial in 60 older adults found higher blood NAD+ with 250 mg a day [6], and a pooled analysis of 12 NMN trials (513 people) confirmed an overall rise in blood NAD [7]. A 10-week trial in older adults with mild cognitive impairment found a 2.6-fold rise with 1 g a day [8].

Physical function. A 2025 meta-analysis of 10 randomised trials in adults with a mean age over 60 found no clear effect of NMN on muscle mass, grip strength, gait speed or chair-stand time, and concluded the evidence does not support NMN or NR for preserving muscle [9]. A separate 2025 meta-analysis of 9 trials (412 people) reported small improvements in gait speed (standardised mean difference 0.34) and lower ALT liver enzymes with NMN [10]. In single trials, six-minute walking distance improved with NMN over 60 days [5]; in 60 older adults, 12 weeks of NMN was linked to a slightly faster 4-metre walk and better sleep-quality scores, while the primary stepping test was unchanged [6]; and in people with peripheral artery disease, NR improved six-minute walking distance by 17.6 m over six months (31 m in those who took at least 75% of their pills) [11].

Exercise endurance. In a 2026 network meta-analysis of 27 studies (1,599 people), medium and high doses of NMN improved endurance-type performance (standardised mean difference 0.66 and 1.02), while muscle strength did not improve with any precursor [2]. A 6-week trial in 48 amateur runners found medium and high doses of NMN improved oxygen uptake and ventilatory-threshold power during training [12]. In a 12-week trial in Friedreich's ataxia, NR plus exercise improved peak VO2 versus control, but was not better than exercise alone [13].

Fatigue and sleep. The 2026 network meta-analysis found no significant improvement in perceived fatigue for any NAD+ precursor (pairwise standardised mean difference -0.15, not significant) and no benefit for sleep quality [2]. Some single trials disagree: a 12-week trial in 108 older adults reported less afternoon drowsiness with NMN [14], and the 12-week trial above found better sleep-quality scores [6].

Metabolism and blood pressure. Pooled data from 8 randomised trials (342 adults) found no significant effect of NMN on fasting glucose, insulin, HbA1c, insulin resistance or lipids [15]. A larger 2024 meta-analysis of 19 trials found lower total cholesterol and triglycerides but no other metabolic-syndrome changes, with evidence quality rated very low to low [16]. One small trial in 30 adults with overweight found lower weight, LDL cholesterol and diastolic blood pressure after 28 days of NMN [17], and a 10-week trial found improved muscle insulin sensitivity in postmenopausal women with prediabetes [18]. On blood pressure, a 2026 meta-analysis of 10 trials (349 people) found diastolic pressure about 2 mmHg lower with NMN, and systolic pressure about 4 mmHg lower in people aged 60 and over; the authors called the evidence preliminary [19].

Brain and cognition. Two small randomised trials in mild cognitive impairment found NR raised blood NAD+ but did not improve cognition [8][20]. The 2026 network meta-analysis found a cognitive signal only for NADH, a different precursor, not for NR or NMN [2]. A 22-person crossover trial found NR reduced some neurodegeneration-related proteins in blood-borne particles from nerve cells [21].

Longevity. No human trial has measured whether NR or NMN extend life, and the 2026 review found clinical effectiveness for anti-aging outcomes not established [1]. One 10-week trial in 20 people reported small, exploratory reductions in epigenetic age clocks [8], and a 60-day trial found blood biological age did not rise in NMN groups while it rose slightly with placebo [5].

Doses used in studies

NR: 100, 300 and 1,000 mg a day for 8 weeks in the dose-finding trial [4]; 1,000 mg a day in a 6-week crossover study [22] and a 30-day Parkinson's trial [23]; up to 3,000 mg a day for 4 weeks in a safety trial, where blood NAD+ rose up to 5-fold [24]. NMN: 250 mg a day for 12 weeks [6]; 300 to 900 mg a day for 60 days [5]; 300 to 1,200 mg a day for 6 weeks in runners [12]; 1,000 mg a day for 14 days in the head-to-head trial [3]; 1,250 mg a day for 4 weeks in a safety trial [25]; and 250 to 2,000 mg a day across 15 trials in a safety review [26]. Across the fatigue trials, NR and NMN were given at 250 to 3,000 mg a day for 2 to 48 weeks [2].

Safety and interactions

Side effects. A 2026 meta-analysis of 10 randomised NMN trials (250–2,000 mg a day, 14 days to 24 weeks) found no increase in overall, serious or system-specific side effects and no rise in liver enzymes versus placebo [26]. NR has been given at 3,000 mg a day for 4 weeks with no moderate or severe side effects [24] and at 2,000 mg a day for 12 weeks without serious events [27]. In the head-to-head trial, three mild events were probably product-related: headache (NMN), a drop in blood pressure (NR) and abdominal pain (placebo) [3]. A Friedreich's ataxia trial reported mild or moderate gut symptoms, falls, infections and rashes across all groups [13].

Upper limits. None is established, and trials have run for weeks to a few months, so data beyond about six months are scarce [1].

Interactions. The safety analyses did not test interactions with medicines [26], and no interaction studies were found in these searches.

Pregnancy and breastfeeding. No safety data exist in pregnancy or breastfeeding.

Conditions to consider. A 2020 benefit–risk review flagged theoretical concerns about tumour promotion and the build-up of potentially harmful breakdown products when NAD+ is raised, and called for long-term human data [28]. Because long-term safety data are missing, people with cancer or liver or kidney disease should ask a doctor before using these supplements [1].

Caveats and open questions

The 2026 review is a synthesis, not a pooled analysis, and most human trials were small and short, with outcomes that varied [1]. Two 2025 meta-analyses of muscle outcomes disagree: one found no pooled effect of NMN in older adults [9], the other small gait-speed gains [10]. Risk of bias is a recurring problem: in one meta-analysis of NMN and metabolic markers, 5 of 12 studies were at high risk of bias and 7 had some concerns [7], and a metabolic-syndrome review rated its evidence very low to low [16]. Not every measurement of NAD+ agrees either: a small 2026 trial found NR raised NAD+ in skin but not in plasma [29]. Some trials were funded or run by supplement makers [4][6], and the head-to-head trial was run by Nestlé Research [3]. Larger ongoing trials listed with this page are testing NR against frailty and functional decline, NMN in middle-aged and older adults, and NAD+ supplements for brain vascular health.