The short answer: NAD+ is part of how your cells make energy, but the human studies so far don't show that raising it makes people feel more energetic.
NAD+ is a coenzyme your cells can't run without. It carries electrons through the reactions that turn food into usable energy. That part isn't in dispute. The question people actually type into Google is different: if I raise my NAD+, will I feel it? The trials that have tested this mostly say no, or "not that we could measure." A few found narrower effects worth knowing about.
Status as of October 25, 2026: there's no FDA-approved NAD+ drug. NAD+ is on FDA's list of substances under evaluation for pharmacy compounding. NMN and NR are sold as dietary supplements. This post describes what published studies measured. It isn't medical advice.
Updated October 25, 2026: rewritten from the August 5 email with the human trial data and current FDA status. The original's product pitch was removed.
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What is NAD+, and what does it do?
NAD+ (nicotinamide adenine dinucleotide) shuttles electrons in metabolism and keeps the cell's redox balance in check. It's also the fuel for three enzyme families that get most of the longevity attention: sirtuins, which help regulate gene expression; PARPs, which repair DNA; and CD38 (Rejuvenation Research, 2019).
That's the useful way to think about it. NAD+ isn't a stimulant. It doesn't work like caffeine, and nothing about its biology says it should feel like a jolt. It sits upstream, in the machinery, which is exactly why "energy" is a slippery word for it.
Does NAD+ decline with age?
Probably, but the human evidence is thinner than the marketing suggests.
A study of plasma from healthy people aged 20 to 87 found NAD+ levels were significantly lower in older people (Rejuvenation Research, 2019). That's one snapshot of blood, not tissue, and not the same people followed over time. A 2019 trial team put it plainly: the decline "has been reported ... in preclinical models, but human data are sparse" (Cell Reports, 2019).
Even if levels do fall, it doesn't follow that topping them back up changes how you feel. That's what the trials were for.
What do the human trials actually show?
The pills work at one thing: raising NAD+ in blood. What happens after that is where the results get thin.
Most human studies test precursors, NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide), which the body converts into NAD+. Here's what the main ones measured.
Form | What was studied | Who and how long | What it found on energy, fatigue or performance |
|---|---|---|---|
NR | NAD+ levels, exercise capacity, blood pressure | 30 healthy middle-aged and older adults, 6 weeks each arm, crossover | NAD+ in blood cells up about 60% vs placebo. No effect on VO2 max, time to exhaustion, motor function or energy expenditure (Nat Commun, 2018) |
NR | Insulin sensitivity, energy expenditure | 40 men with obesity, aged 40 to 70, 12 weeks | No change in insulin sensitivity, resting energy expenditure or body composition (Am J Clin Nutr, 2018) |
NR | Muscle NAD+ and mitochondria | 12 older men, 21 days, crossover | Muscle NAD+ markers up. Mitochondrial energy output unchanged. Inflammatory markers down (Cell Reports, 2019) |
NMN | Muscle insulin sensitivity | 25 postmenopausal women with prediabetes and overweight, 10 weeks | Muscle insulin sensitivity up. Muscle NAD+ itself didn't change (Science, 2021) |
NMN | Aerobic capacity with training | 48 recreational runners, 6 weeks | Some ventilatory-threshold measures up in the higher-amount groups. No difference in VO2 max or peak power (JISSN, 2021) |
NMN | Sleep, fatigue, physical performance | 108 older Japanese adults, 12 weeks | Afternoon NMN group had the biggest gains in a chair-stand test and drowsiness, but every group improved on the chair stand, placebo included (Nutrients, 2022) |
IV NAD+ | What happens to infused NAD+ in blood | 11 healthy men (8 NAD+, 3 saline), one 6-hour infusion | Blood NAD+ didn't rise for the first 2 hours. No energy or fatigue outcomes measured (Front Aging Neurosci, 2019) |
A few things jump out.
Raising NAD+ in blood is the easy part. Almost every trial manages it. A 2026 review of 33 human studies found oral NR and NMN "consistently demonstrated biochemical target engagement," but effects on function, metabolism and blood vessels were "heterogeneous and often null" (Ageing Research Reviews, 2026).
The best-known positive result is narrow. The 2021 Science trial found better muscle insulin sensitivity in 25 women with prediabetes. That's a real finding in a specific group. It's not a fatigue result, and NAD+ in their muscle didn't measurably change.
The fatigue study has a placebo problem. In the Japanese trial, people on placebo improved on the chair-stand test too. Two of its authors work for a company that makes NMN, though the paper reports no conflict of interest.
The pooled data lean null. A meta-analysis of eight NMN trials in 342 adults found no significant benefit on blood sugar, insulin or lipids (Curr Diab Rep, 2024). Another found the evidence "does not support NMN and NR supplementation for preserving muscle mass and function" in adults over 60 (J Cachexia Sarcopenia Muscle, 2025). A July 2026 meta-analysis of 15 trials found NMN well tolerated, with a slight drop in diastolic blood pressure, but "broad metabolic benefits were not evident" (Nutrients, 2026).
What about NAD+ IVs and shots?
This is where the gap between marketing and data is widest.
The 2026 review found no outcome trials of intravenous or intramuscular NAD+ itself for wellness or anti-aging (Ageing Research Reviews, 2026). The one infusion study it pointed to tracked what happened to NAD+ in the blood of 11 men. It didn't measure energy at all, and found infused NAD+ was "rapidly and completely removed from the plasma for at least the first 2 h" (Front Aging Neurosci, 2019).
So when a clinic says an NAD+ drip "boosts energy," there isn't a controlled trial behind that sentence. People do report feeling different afterward. That's a report, not a measurement, and it's exactly what placebo groups exist to sort out.
Is NAD+ legal? Where does it stand with the FDA?
There's no FDA-approved NAD+ drug. A search of FDA's drug approval database for NAD+ (nadide) returns nothing (openFDA).
Compounding: NAD+ and NADH are in Category 1, "under evaluation," on FDA's 503A nominations list (FDA, May 14, 2026). FDA says it doesn't intend to take action against pharmacies compounding with Category 1 substances if they meet the guidance conditions (FDA). That's an interim policy, not an approval.
NMN supplements: In 2022 FDA said NMN couldn't be sold as a supplement because it had been studied as a drug. It reversed that in September 2025 after industry petitions (National Law Review, Sept 30, 2025).
For the other compounds people lump in with NAD+ under "mitochondrial," see MOTS-c vs SS-31. For what "pharmaceutical grade" means on a label (and what it doesn't), see research grade vs pharmaceutical grade. And if you're tired and trying to figure out why, start with bloodwork, not a coenzyme.
So does NAD+ give you energy?
Not in any way the trials have been able to measure so far.
NAD+ is foundational to how cells make energy. Raising it in blood is easy. Turning that into more energy, better endurance or less fatigue in people hasn't shown up consistently in controlled trials. The positives so far are specific (muscle insulin sensitivity in one group of women, some threshold measures in trained runners), and the IV version hasn't been tested for energy at all.
The better question was never "what gives me more energy?" It's "what does my body actually need, and how would I know?" That's a bloodwork-and-sleep question before it's a supplement question.
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If you've tried NR, NMN or an NAD+ drip, reply and tell me what you noticed, and whether you tracked anything besides how you felt.