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9 NAD+ Benefits for Energy, Aging & Metabolism

NAD+ benefits are some of the most repeated claims in longevity medicine. Here are nine, each graded by its human evidence and the form that was actually tested, because most of the data comes from oral precursors and animal studies, not from NAD+ injections.

Clinically reviewed
Medically reviewed by Harbor Health TeamMedical Content Team6 min read
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The top three

Mostly oral NR and NMN, small groups
Our pick

01  Cellular energy production

Real role, unproven boost

21 daysof oral NR, no change in mitochondrial function

02  Healthy aging & sirtuin activity

Levels rise, aging unproven

60%higher NAD+ in blood cells on oral NR

03  Metabolic health & insulin sensitivity

One bright spot, mostly null

25women in the one positive trial

Levels rise, outcomes lag. Oral precursors reliably raise NAD+ in blood. Effects on how people feel and function have been mixed or null, and a 2026 systematic review found no outcome trials of injected or IV NAD+ for wellness.

NAD+ benefits at a glance

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme in every cell. It carries electrons as food becomes energy, and sirtuins and PARPs, enzymes of aging biology and DNA repair, consume it.

Those textbook roles are the source of most claimed NAD benefits. The benefits of NAD as a treatment are less settled: levels fall with age in human skin and brain in some studies, yet a 2026 analysis of seven cohorts found whole-blood NAD+ stable with age. Harbor explains the basics in what is NAD therapy.

Each benefit is graded A for randomized human trials with a measurable result, B for small, mixed or surrogate-only human data, or C for animal, lab or mechanism only.

NAD+ benefits backed by research

Most NAD+ benefits in this list rest on mouse studies or on oral precursors, nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), which the body converts into NAD+. A NAD+ metabolism during aging review concludes precursors are safe and raise NAD+ in healthy volunteers, but whether that helps aging humans is unknown.

Despite common searches for NAD peptide benefits, NAD+ is not a peptide but a dinucleotide, with no amino acids. NAD plus benefits claimed for injections rest mostly on precursor trials. For food, exercise and sleep habits first, see how to increase NAD levels.

01

Cellular energy production

Established biology, grade C for supplementing

21 daysof oral NR, no change in mitochondrial function

NAD+ is essential for making ATP, the cell's energy currency. Raising NAD+ has not been shown to improve energy production in people.

Where it wins

  • Oral NR raised muscle NAD+ metabolites in 12 older men
  • It also lowered circulating inflammatory cytokines

What it costs you

  • Mitochondrial bioenergetics did not change
  • No change in energy expenditure over 12 weeks in 40 men
  • Fatigue and felt energy went unmeasured

Real role, unproven boost

02

Healthy aging & sirtuin activity

Grade A for raising levels, C for aging

60%higher NAD+ in blood cells on oral NR

Sirtuins, enzymes tied to aging in animal studies, need NAD+. The solid human finding is narrower: oral NR raises NAD+ levels.

Where it wins

  • 1,000 mg of NR a day raised NAD+ in blood cells about 60% in 30 adults aged 55 to 79
  • Single doses raised blood NAD+ within hours

What it costs you

  • No human trial shows slower aging or longer life
  • Lifespan data come from mice
  • Several trials have supplement-industry ties

Levels rise, aging unproven

03

Metabolic health & insulin sensitivity

Mixed human trials, grade B

25women in the one positive trial

One 10-week oral NMN trial in 25 postmenopausal women with prediabetes was positive, while larger trials in men and two meta-analyses mostly found no effect.

Where it wins

  • NMN 250 mg a day improved muscle insulin sensitivity in women with prediabetes
  • A meta-analysis of 19 trials found lower total cholesterol and triglycerides

What it costs you

  • 2,000 mg of NR a day for 12 weeks did not improve insulin sensitivity in 40 obese men
  • A 15-trial NMN meta-analysis found no effect on glucose, HbA1c or weight

One bright spot, mostly null

04

DNA repair

Mechanism only, grade C

Nonehuman trials in healthy people

PARP enzymes use large amounts of NAD+ to repair damaged DNA, yet no human trial shows extra NAD+ or a precursor improving that repair in healthy people.

Where it wins

  • Strong mechanism in cell and animal work
  • Open-label NR studies in a rare DNA-repair disorder reported better coordination

What it costs you

  • Rare-disease data do not transfer to healthy adults
  • Skin NAD+ and PARP data are correlations only

Mechanism, not evidence

05

Brain function & focus

Grade B, cognition unchanged

2xblood NAD+, no cognitive change

Oral NR can raise brain NAD+, but in two trials in mild cognitive impairment, memory and thinking did not improve.

Where it wins

  • 30 days of NR raised brain NAD+ in a Parkinson's trial
  • Responders showed altered brain metabolism and mild clinical change

What it costs you

  • 12 weeks of NR doubled blood NAD+ with no cognitive gain in 42 people with MCI
  • No trial in healthy adults shows better focus

Levels up, thinking unchanged

06

Muscle function & exercise

Small mixed trials, grade B

42older men, nominal gait and grip gains

Small NMN trials reported some gains in gait speed, grip or aerobic measures, but a 2025 meta-analysis does not support NMN or NR for muscle mass and function after 60.

Where it wins

  • NMN 250 mg a day nudged gait speed and grip in 42 older men
  • Amateur runners on higher NMN doses improved some aerobic measures

What it costs you

  • No change in body composition
  • VO2max did not change in the runners
  • Meta-analysis: no support for muscle benefits over 60

Not supported by pooled data

07

Heart & blood vessel health

Grade B, small or patient-only trials

180heart failure patients in the one IV NAD+ trial

Oral NR showed a blood pressure trend, not significant after correction. The only randomized outcome trial of NAD+ itself enrolled hospital patients with heart failure.

Where it wins

  • NR lowered systolic pressure 3.9 mmHg on average, a trend only
  • In 180 heart failure patients, 7 days of IV NAD+ raised ejection fraction to 45.4% vs 42.4% at one month

What it costs you

  • The heart failure trial was single-center, in sick patients, at 10 mg a day IV
  • Major cardiac events did not differ significantly
  • Meta-analysis BP effects were driven by niacin, not NAD+

Patient data, not prevention

08

Sleep & circadian rhythm

Mostly animal, grade C

108older adults, no sleep-quality change

In 108 older adults, 12 weeks of afternoon NMN reduced drowsiness without changing measured sleep quality.

Where it wins

  • The body clock and NAD+ are linked in animal research
  • Afternoon NMN reduced daytime drowsiness

What it costs you

  • Drowsiness also improved in the afternoon placebo group
  • No change on the Pittsburgh Sleep Quality Index
  • Funded by an NMN maker

Animal link, weak human data

09

Skin health

No NAD+ data, grade C

23%fewer skin cancers on nicotinamide, not NAD+

No human trial has tested NAD+ itself on skin. The often-cited 23% drop in nonmelanoma skin cancers came from oral nicotinamide, a vitamin B3, in high-risk patients.

Where it wins

  • Nicotinamide 500 mg twice daily cut new skin cancers 23% over 12 months
  • NAD+ falls with age in human skin in one study

What it costs you

  • Nicotinamide is a precursor, not NAD+
  • The benefit stopped when nicotinamide stopped
  • No cosmetic skin outcomes tested

Precursor result, not NAD+

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How to choose an NAD+ form

Form matters: NAD supplement benefits here come almost entirely from oral NR and NMN.

  • IV infusion: in a pilot, plasma NAD+ held flat for the first 2 hours of a 6-hour infusion. The NAD IV therapy benefits clinics claim rest on one patient outcome trial, in heart failure. In one chart review, faster infusions caused nausea, a raised heart rate and chest pressure.
  • Injection: NAD injections benefits, under the skin or into muscle, have no published efficacy trial. A trial of injected NAD+ comfort and absorption is still recruiting.
  • Oral precursors: the best-studied route, sold as supplements the FDA does not approve before sale.

NAD+ is also under FDA evaluation for compounding, which means it is not an FDA-approved drug. Harbor NAD+ injections start at $99 a month, are compounded by a licensed U.S. pharmacy and are prescribed only after a clinician reviews your health history. Treat any NAD+ injections benefits as support under clinician supervision, not a promise. If it is not the right fit, it is not prescribed.

Many people pair NAD+ with glutathione, and taking NAD+ & glutathione together covers timing and order.

When to get care now

Chest pain or pressure, trouble breathing, or swelling of the face or throat after a dose needs emergency care. For flushing, nausea or soreness where you inject, message your Harbor clinician before your next dose.

Frequently asked questions

None is proven in a published wellness trial. A 2026 systematic review found no outcome trials of IV or intramuscular NAD+ for aging or wellness.

No human trial has compared them. The one positive metabolic trial enrolled only women and several others only men, so evidence on NAD benefits for women and on NAD+ benefits for men comes from separate studies.

Blood NAD+ rises within hours to weeks on oral precursors. Nearly all trials measured function at 3 to 12 weeks, and most found no change. There is no reliable timeline for felt NAD+ benefits.

Sources

  1. Covarrubias AJ et al. NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol. 2021.
  2. NAD, MeSH, NIH.
  3. Tretowicz MM et al. Human whole-blood NAD+ levels do not vary with age or lifestyle interventions. Nat Metab. 2026.
  4. Massudi H et al. Age-associated changes in NAD+ in human skin. PLoS One. 2012.
  5. Gallagher C, Emmanuel OO. NAD+ for anti-aging and wellness: systematic review. Ageing Res Rev. 2026.
  6. Elhassan YS et al. Nicotinamide riboside in aged human muscle. Cell Rep. 2019.
  7. Martens CR et al. Nicotinamide riboside in healthy middle-aged and older adults. Nat Commun. 2018.
  8. Trammell SAJ et al. Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. Nat Commun. 2016.
  9. Yoshino M et al. NMN increases muscle insulin sensitivity in prediabetic women. Science. 2021.
  10. Dollerup OL et al. Nicotinamide riboside in obese, insulin-resistant men. Am J Clin Nutr. 2018.
  11. Oliveira-Cruz A et al. NAD+ precursors and metabolic outcomes: meta-analysis. Horm Metab Res. 2024.
  12. Yang W et al. NMN supplementation: meta-analysis of RCTs. Nutrients. 2026.
  13. Veenhuis SJG et al. Nicotinamide riboside in ataxia telangiectasia. Mov Disord. 2021.
  14. Brakedal B et al. The NADPARK study. Cell Metab. 2022.
  15. Martens CR et al. Nicotinamide riboside in mild cognitive impairment. Alzheimers Dement. 2026.
  16. Igarashi M et al. NMN in older men. NPJ Aging. 2022.
  17. Liao B et al. NMN in amateur runners. J Int Soc Sports Nutr. 2021.
  18. Prokopidis K et al. NAD+ precursors and muscle in older adults: meta-analysis. J Cachexia Sarcopenia Muscle. 2025.
  19. Lei L et al. NAD+ precursors and cardiovascular risk factors: meta-analysis. Eur J Clin Invest. 2023.
  20. Yu X et al. IV NAD+ in ischemic cardiomyopathy. Am J Cardiovasc Drugs. 2026.
  21. Nakahata Y et al. Circadian control of NAD+ salvage. Science. 2009.
  22. Kim M et al. NMN timing in older adults. Nutrients. 2022.
  23. Chen AC et al. Nicotinamide for skin-cancer chemoprevention (ONTRAC). N Engl J Med. 2015.
  24. Grant R et al. Plasma and urine NAD+ during a 6-hour IV NAD infusion. Front Aging Neurosci. 2019.
  25. Reyna K et al. IV NAD+ vs IV NR infusion tolerability. Front Aging. 2026.
  26. Injectable NAD+ vs nicotinamide riboside absorption and tolerability trial, ClinicalTrials.gov.
  27. FDA 503A bulk drug substance categories, updated May 14, 2026.
  28. FDA 101: Dietary supplements.

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