Question explored with the scientific record
Nad+
NAD+ supplements reliably raise a lab number in your blood. Whether that makes you healthier is unproven.
The honest answer is that NAD+ is a real molecule your cells depend on, and its levels do fall with age in animals [2]. But the supplement trials measure the wrong thing. A review of six randomized trials found oral NMN (a precursor your body converts to NAD+) at 250 to 900 mg a day raised blood NAD in 275 adults [1]. That is a lab reading, not a health outcome. The trials that did look at real function came back mixed: a 60-day trial of 80 healthy middle-aged adults found longer six-minute walk distance versus placebo, but also a rise in insulin resistance at the 600 and 900 mg doses [4]. A 24-week trial of 1250 mg a day in older adults raised blood NAD about 3.6-fold yet improved nothing that mattered: hearing, grip strength, gait speed, and the six-minute walk all showed no benefit [6].
| Trial | Dose / length | Blood NAD | Real-world outcome |
|---|---|---|---|
| Dose-ranging, 80 adults [4] | 300–900 mg, 60 days | Rose | Walk distance up; insulin resistance up at high dose |
| Older men, 20 people [5] | 250 mg, 12 weeks | Rose | Gait and left grip nominally up; muscle mass flat |
| Older adults, 58 people [6] | 1250 mg, 24 weeks | Rose 3.6-fold | No hearing or physical gains |
| Arterial stiffness, 36 adults [3] | 250 mg, 12 weeks | Nicotinamide up | Stiffness trend only |
The safety data is short. Trials ran 60 days to 24 weeks, with mostly mild side effects [1][4][6]. One participant on high-dose NMN stopped for elevated liver enzymes, and a link could not be fully excluded [6]. No long-term data exists. A review of ovarian claims found no human trial has tested fertility or pregnancy outcomes at all [7]. These searches did not surface the funding sources, so I cannot tell you who paid.
My call: skip it unless you have a specific diagnosed deficiency. The evidence shows it moves a biomarker, not that it extends health or life, and the longest, highest-dose trial found nothing. Confidence: moderate.
Sources used 7
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EFFICACY OF NICOTINAMIDE MONONUCLEOTIDE SUPPLEMENTATION (NMN) IN BLOOD NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD) FOR ANTI-AGING IN ADULTS: A SYSTEMATIC REVIEW
A systematic review of six RCTs found that oral NMN supplementation (250–900 mg/day for 10–12 weeks) significantly increased blood NAD concentrations in adults, with only mild adverse effects, supporting its potential anti-aging benefit.
DOI: 10.61841/gyj2gr52 -
Nicotinamide adenine dinucleotide homeostasis and signalling in heart disease: Pathophysiological implications and therapeutic potential
This 2015 review synthesizes how nicotinamide adenine dinucleotide (NAD+) homeostasis and NAD+-dependent signaling are altered in heart disease, detailing how NAD+ metabolism interfaces with Ca2+ signaling, mitochondria, and oxidative stress, and outlining therapeutic strategies…
DOI: 10.1016/j.acvd.2015.10.004 -
Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial
A 12-week randomized, double-blind, placebo-controlled trial in 36 healthy middle-aged adults found that 250 mg/day nicotinamide mononucleotide (NMN) was safe and significantly increased serum nicotinamide levels, while only a trend toward reduced arterial stiffness (baPWV) was …
DOI: 10.1038/s41598-023-29787-3 -
The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial
In a 60-day double-blind dose-ranging trial in 80 healthy middle-aged adults, oral NMN (300-900 mg/day) raised blood NAD, improved walking distance, and prevented biological-age increase while being safe, although HOMA-IR rose in the 600 and 900 mg groups.
DOI: 10.1007/s11357-022-00705-1 -
Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men
In healthy older men, 250 mg/day oral NMN for 12 weeks raised whole-blood NAD+ and related metabolites, was well tolerated, and nominally improved gait speed and left grip strength but not muscle mass.
DOI: 10.1038/s41514-022-00084-z -
Sustained NAD⁺ augmentation by high-dose nicotinamide mononucleotide supplementation in older adults: a 24-week randomized, double-blind, placebo-controlled trial
In healthy older adults, 24 weeks of 1250 mg/day NMN robustly raised blood NAD⁺ and related metabolites but did not improve hearing, physical performance, or other physiological outcomes.
DOI: 10.1038/s41514-026-00482-7 -
The impact of nicotinamide mononucleotide on ovarian health: A comprehensive literature review of preclinical evidence and therapeutic potential
Preclinical rodent and in vitro studies indicate NMN supplementation improves ovarian NAD+ levels, mitochondrial function, oocyte quality, and endocrine function, but no clinical trial has tested reproductive endpoints in women.
DOI: 10.5653/cerm.2026.09488