NAD+

Nicotinamide adenine dinucleotide · redox coenzyme (not a peptide)

NAD+ is not a peptide — it is a coenzyme, one of the most fundamental molecules in the cell. It is the electron carrier that powers how you turn food into energy (in glycolysis, the citric-acid cycle, and the mitochondria), and it is the fuel that NAD+-consuming enzymes such as the sirtuins, PARPs, and CD38 burn to do their jobs. Because cellular NAD+ appears to fall with age in animal tissue, a large longevity industry now sells ways to 'restore' it. Here is the honest split. Almost all of the real human clinical evidence is for ORAL PRECURSORS — nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) — which do reliably raise the NAD+ level in your blood, but which have shown weak, inconsistent, or no clinical benefit in controlled trials (and the best-looking results tend to come from studies funded by the companies selling the product). The injectable / IV NAD+ that clinics market is a different and far thinner story: there is essentially one small human pharmacokinetic pilot and one retrospective tolerability review, and no completed controlled trial showing that IV or injected NAD+ produces a clinical benefit. That pilot also suggests infused NAD+ is largely broken down outside the cell before it can be used. This page lays out the settled biochemistry, separates the precursor evidence from the injectable hype, and marks clearly where the human proof simply isn't in.

The short version

NAD+ is one of the handful of catalog items that is not a peptide at all — it is a coenzyme, a small 'helper molecule' that your cells cannot run without. Its day job is to shuttle electrons during the chemistry that converts food into usable energy. Without enough NAD+, energy metabolism grinds.

NAD+ is also the raw material that a set of important enzymes consume to work — most famously the 'sirtuins' (often linked to aging research), the DNA-repair enzymes called PARPs, and an enzyme called CD38. Because animal studies suggest tissue NAD+ tends to drop as we get older, a whole longevity industry has grown up around the idea of topping it back up.

This is where it pays to be careful. Most of the solid human evidence is not for NAD+ itself, but for two oral 'precursor' supplements — nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) — that the body converts into NAD+. Those do reliably raise the NAD+ level measured in your blood. What they have mostly NOT done in good trials is produce a clear health benefit: results are weak, mixed, or absent, and the best-looking studies are often funded by the companies that sell the product.

The injectable and IV NAD+ that drip clinics sell is a much thinner story still. There is roughly one small human study of what an IV dose actually does in the body, and one review of how well people tolerate it — and essentially no completed controlled trial showing it makes anyone healthier. That pharmacokinetic study even suggests that a lot of infused NAD+ is broken apart outside your cells before it can be used. This page keeps the textbook biochemistry separate from the marketing, and is explicit about where the human proof stops.

Molecular identity

Specs

Molecular weight: 663.4 g/mol
Molecular formula: C21H27N7O14P2
Monoisotopic mass: 663.1091 Da
XLogP: −6 (extremely hydrophilic)
Topological polar surface area: 321 Å²
H-bond donors / acceptors: 7 donors · 18 acceptors
CAS / UNII: 53-84-9 · 0U46U6E8UK

Compound class: Dinucleotide redox coenzyme (not a peptide)PubChem CID 5892
IUPAC name: [[(2R,3S,4R,5R)-5-(6-aminopurin-9-yl)-3,4-dihydroxyoxolan-2-yl]methoxy-hydroxyphosphoryl] [(2R,3S,4R,5R)-5-(3-carbamoylpyridin-1-ium-1-yl)-3,4-dihydroxyoxolan-2-yl]methyl phosphatePubChem CID 5892
Structure: Adenine + nicotinamide bases, two ribose sugars, joined by a pyrophosphate (di-phosphate) bridgePubChem CID 5892
Water solubility: Freely water-soluble (highly polar; XLogP −6)PubChem CID 5892
Reduced form (NADH): C21H29N7O14P2, MW 665.4 g/mol (carries the extra hydride)PubChem CID 439153
Molecular role: Electron-carrying coenzyme; substrate for sirtuins, PARPs, CD38; salvage pathway via NAMPTResearch literature
Plasma half-life: Not established — the one human IV pilot tracked delayed metabolite appearance, not a t½; infused NAD+ is rapidly degraded extracellularly to nicotinamide + ADP-ribosePMID 31572171
Regulatory status: Not an FDA-approved drug; IV/injectable NAD+ is compounded, not FDA-reviewedFDA compounding guidance

Plain English

Mechanism

NAD+ (nicotinamide adenine dinucleotide) is a dinucleotide coenzyme (a small helper molecule built from two nucleotide units): two nucleotide halves — one built on adenine, one on nicotinamide — joined by a pyrophosphate bridge (a double-phosphate link). Its best-known role is as the cell's principal electron carrier — the molecule that ferries electrons from one reaction to the next. In catabolism (the breakdown of food for energy — glycolysis and the citric-acid/TCA cycle) NAD+ accepts electrons to become NADH; NADH then donates those electrons to the mitochondrial electron-transport chain (the energy assembly line inside the cell's powerhouses) to drive oxidative phosphorylation and ATP synthesis — the making of ATP, the cell's energy currency. This redox cycling (the back-and-forth of gaining and losing electrons) is settled, textbook biochemistry — not contested.

Beyond redox cycling, NAD+ is also a consumable SUBSTRATE (a raw material that gets used up) for a family of enzymes that cleave it. The sirtuins (SIRT1–7) are NAD+-dependent deacylases (enzymes that strip chemical tags off proteins) central to much aging research; the PARPs (poly-ADP-ribose polymerases) consume NAD+ during DNA-damage repair; and CD38/CD157 are NADases (enzymes that break NAD+ apart) that degrade NAD+ into nicotinamide and ADP-ribose. Because these enzymes destroy NAD+ to function, their activity is a major determinant of how much NAD+ a cell has.

Cells replenish NAD+ mainly through the salvage pathway (the recycling route that rebuilds NAD+ from its own breakdown pieces), in which the enzyme NAMPT recycles nicotinamide back toward NAD+ (NAMPT is the rate-limiting step — the slowest, bottleneck reaction); there is also a de-novo route (building it from scratch) from the amino acid tryptophan and the Preiss-Handler route from nicotinic acid (a form of vitamin B3). Oral precursor supplements (NR, NMN — building-block molecules the body turns into NAD+) feed into these pathways — which is why they raise blood NAD+ — rather than delivering intact NAD+.

The longevity thesis is that tissue NAD+ falls with age, dragging down mitochondrial and metabolic function, and that restoring it is beneficial. The mechanistic evidence has shifted from 'decline is mainly reduced synthesis' toward 'decline is driven by increased CONSUMPTION,' especially by CD38 (Camacho-Pereira/Chini 2016, largely mouse data with some human adipose confirmation). But the popular headline figures ('NAD+ drops 50% by age 50') are not backed by a citable controlled human study across tissues — they rest on small cross-sectional samples and animal extrapolation, and are treated here as marketing-adjacent rather than primary-source fact.

Sources:PubChem CID 5892 PMC4911708

Why people reach for it

Potential benefits

NAD+ is reached for as the foundational 'cellular energy and longevity' molecule. Here's what draws people to it — with the honest split that most solid human evidence is for oral precursors, not the injectable form.

Cellular energy support — NAD+ is the electron carrier at the center of how cells turn food into ATP — the energy currency — which is the core reason people pursue it for daytime energy and metabolic vitality.
The longevity 'fuel' angle — NAD+ is the substrate that sirtuins and PARPs burn to do their jobs, and tissue NAD+ appears to fall with age in animal studies — the rationale behind topping it back up, even though the popular age-decline percentages aren't backed by a controlled human study.
A metabolic and mitochondrial base — Because NAD+ fuels the mitochondrial electron-transport chain, it's reached for as a base layer in metabolic and mitochondrial stacks rather than for a single targeted effect.
Pairs across the mitochondrial cluster — It slots cleanly alongside other mito levers — most commonly MOTS-c for the AMPK signal and SS-31 for membrane protection — supplying the redox currency the others' programs draw on.
Oral-precursor track record (NR / NMN) — The related oral precursors NR and NMN reliably raise blood NAD+ in controlled trials — part of NAD+'s appeal — though that's a measurable biomarker rise, not a proven clinical benefit, and the injectable form is a much thinner evidence story.

Sources:PubChem CID 5892 PMID 31278280 PMID 36482258 PMC4911708

What people reach for NAD+ for, drawn from its settled biochemistry and how it's used — not proven human outcomes. Honest split: the real human evidence is mostly for oral precursors (NR/NMN) raising blood NAD+, with weak/inconsistent clinical benefit; injectable/IV NAD+ has no completed outcome trial. No medical claims.

Implied timing

Best time to dose

Implied best time

Morning (slow)

Most people take NAD+ in the morning — and inject or infuse it slowly, because flushing and nausea climb sharply with speed.

NAD+ feeds the daytime energy machinery (the electron-transport chain that powers ATP production), so it's paired with the active part of the day; a dose just before sleep is specifically avoided.
Speed matters more than the clock: flushing, nausea, and chest pressure are rate-driven (in the one IV pilot, only the slow ~6-hour infusion produced no adverse events). Inject SC slowly, titrate the dose up gradually, and stay well-hydrated — morning makes those reactions easier to manage while awake.
No validated human pharmacokinetics or half-life exists for NAD+ (the single IV pilot tracked delayed metabolite appearance, not a clean half-life), so the timing is reasoned from its energy mechanism and tolerability — not a measured duration of action.

No study establishes an ideal time of day for NAD+ — this is reasoned from its mechanism and how it's used. As a rule of thumb most dosing lands in the midday-to-evening window; for NAD+ the lean is morning, and the more important rule is to go slow regardless of the hour.

Sources:PMID 31572171

How to run it

Dosing & protocol

NAD+ is dosed here as a subcutaneous injection — the form sold as a research compound and the route the on-page calculator is built for. It has no validated human therapeutic dose; the figures below are community and clinic convention drawn from the single published IV pharmacokinetic pilot (Grant 2019) and practical SC usage patterns. Read this as how people actually run injectable NAD+ — not a recommendation.

Community convention, not trial-proven: there is no completed controlled trial showing IV or injectable NAD+ produces a clinical outcome benefit, and no primary human PK or efficacy data exist for SC administration specifically. A second honesty note: more NAD+ substrate does not equal more health — clinical outcome evidence is weak even when blood NAD+ is measurably raised. Every number here is a usage pattern, not evidence.

Tiered dose ranges

SC NAD+ is community-range only — start low because flushing and nausea increase sharply with dose and speed.

Starting / tolerance-test:: 50 mg subcutaneously once daily for the first week — the floor dose that establishes tolerability and lets you observe flushing, nausea, or site reaction at the lowest effective range.
Standard SC range:: 50–100 mg once daily — the range most often described for ongoing subcutaneous use. Flushing risk climbs toward the top; some users split into two 50 mg injections.
IV clinic protocol (reference):: 750 mg administered intravenously over ~6 hours — the only published human PK dose (Grant 2019). Drip rate drives reactions: faster rates provoke flushing, nausea, chest pressure; slow infusion was the only rate that produced no adverse events in that pilot.

Subcutaneous administration

NAD+ is injected into subcutaneous fat; site, rotation, and timing are the actionable choices.

Injection site:: The abdomen (two or more inches clear of the navel), the outer thigh, or the love-handle area. Rotate between sites each injection — prevents local irritation and fatty deposits (lipohypertrophy) at a repeated site.
Measuring the dose:: Drawn on a U-100 insulin syringe from the reconstituted vial. At the standard mix (100 mg vial + 1 mL BAC water = 100 mg/mL): 50 mg = 50 IU · 75 mg = 75 IU · 100 mg = 100 IU. The calculator handles any vial size.
Time of day:: Morning is conventional for once-daily dosing — flushing and nausea are easier to manage while awake and hydrated. Do not inject just before sleep.
Food window:: Subcutaneous injection is independent of meals. Staying well-hydrated before and after the injection reduces flushing intensity for most users.

Cycle & washout

NAD+ precursor and IV protocols in research are typically run as blocks of weeks; SC convention follows a similar rhythm.

Standard cycle:: 4–8 weeks of daily use, then reassess. IV clinic protocols often run 5–10 consecutive sessions (days) as a loading course, then monthly maintenance — a pattern some SC users mirror.
Washout:: 2–4 weeks off. During the break is when to recheck any metabolic or energy markers you are tracking — the trend during washout is more informative than the on-protocol value.
Honest note:: No controlled SC NAD+ cycling protocol exists in the literature. These timelines are adapted from NR/NMN trial durations (8-week blocks being most common) and IV clinic convention — not from SC-specific data.

Reconstitution at a glance

The on-page calculator does this live; quick reference for a 100 mg vial:

Mixing:: 100 mg vial + 1 mL bacteriostatic water = 100 mg per mL (100,000 mcg/mL). On a 100-unit (1 mL) U-100 insulin syringe: 50 mg = 50 IU · 75 mg = 75 IU · 100 mg = 100 IU (full syringe).
Why 1 mL:: The 1:1 mix keeps the math simple at these milligram-scale doses and avoids the large injection volumes a more dilute mix would require for a subcutaneous site.

Sources:PMID 31572171 PMID 41704678 PMID 31278280 PMID 36482258

Substrate the signal needs

Nutritional cofactor precision

NAD+ is both a redox carrier and a consumable substrate — it gets used up by sirtuins, PARPs, and CD38 to do their jobs. The cofactors below group by the three functional questions: SUPPLY the substrate the body builds NAD+ from; AMPLIFY the mitochondrial machinery NAD+ feeds; MITIGATE the rate-driven flushing and nausea that limit SC and IV dosing.

Reasoned from NAD+'s salvage-pathway biochemistry and mitochondrial mechanism — not an NAD+ cofactor study. Honest backdrop: feeding more precursors raises blood NAD+ but controlled trials have shown weak or inconsistent clinical benefit. More substrate is not the same as more health.

SUPPLY the substrate — NAD+ biosynthetic inputs

These feed the three routes the body uses to build NAD+: the salvage pathway (NAMPT), the Preiss-Handler route (niacin), and the de-novo route (tryptophan). They reliably raise blood NAD+ levels.

Niacin (nicotinic acid) · Preiss-Handler route:: 25–50 mg niacin once daily alongside injectable NAD+ tops up the Preiss-Handler route and feeds the same pool. Keep doses below 35 mg to avoid flush — the NIH Tolerable Upper Intake Level for niacin is set at 35 mg/day based on flushing (NIH ODS).
NR or NMN · salvage-route precursors:: 100–300 mg nicotinamide riboside (NR) or NMN once daily feeds the salvage pathway and reliably raises blood NAD+. Oral precursors + SC injectable are pulling on the same pool — additive substrate, same weak-outcome caveat applies to both.
Tryptophan · de-novo route substrate:: Adequate dietary protein (≥1.2 g/kg body weight daily) ensures enough tryptophan for the de-novo NAD+ synthesis route. This is diet, not supplementation — a protein-sufficient diet covers it.
TMG (trimethylglycine) · methyl-donor buffer:: 500–1000 mg TMG (betaine) once daily, taken with the precursor dose. The body methylates surplus nicotinamide for excretion, drawing on the methyl pool — TMG replenishes it. Standard pairing whenever NR/NMN doses exceed ~300 mg, or when paired with methylated B12/methylfolate.
Methylated B12 + methylfolate · methyl-cycle support:: Methylcobalamin 1000 mcg + methylfolate 400–800 mcg daily. These support the broader methyl cycle that clearing nicotinamide leans on — especially relevant if you are also running TMG.

AMPLIFY — mitochondrial electron-transport cofactors

NAD+ functions inside the mitochondrial electron-transport chain alongside these co-factors. They amplify the machinery NAD+ feeds rather than raising NAD+ levels directly.

CoQ10 · electron-transport chain component:: 100–200 mg ubiquinol (the reduced, more bioavailable form) once daily with a fatty meal. CoQ10 is the direct downstream acceptor of electrons from NADH in the electron-transport chain — NAD+ and CoQ10 work on the same assembly line; one without the other leaves the chain undersupported.
B-complex (B1, B2, B6) · NAD-adjacent enzyme cofactors:: A full-spectrum B-complex once daily at breakfast. Thiamine (B1), riboflavin (B2, also a redox carrier as FAD/FMN), and B6 all co-operate with NAD+ in the TCA cycle and oxidative phosphorylation — they are the team the electron-transport line runs on.
Magnesium · ATP-synthesis and enzyme cofactor:: 300–400 mg magnesium glycinate or malate daily, in the evening. Magnesium is a required cofactor for ATP synthase (the mitochondrial enzyme that makes ATP from ADP) — NAD+'s endpoint — and for NAMPT, the rate-limiting NAD+-salvage enzyme. Most Western diets are sub-optimal in magnesium.

MITIGATE — flushing and nausea from SC/IV dosing

The dose-rate reactions that limit NAD+ administration — flushing, nausea, chest pressure — have practical offsets.

Dose titration · the primary lever:: Start at 50 mg SC and hold for one week before increasing. Flushing and nausea are strongly dose-and-rate dependent (Grant 2019, Reyna 2026): lower doses and slower IV drip rates nearly eliminate them. Titration is more effective than any supplement for this.
Hydration · flush attenuator:: 500–750 mL water in the 30 minutes before and after SC injection. Adequate pre-hydration is the simplest reported mitigator of NAD+-associated flushing intensity — clinics routinely pair IV NAD+ with a saline co-drip for this reason.
Quercetin · mast-cell stabilizer:: 500 mg isoquercetin 20–30 minutes before injection. Quercetin stabilizes mast-cell membranes and dampens prostaglandin-driven flushing — the same mechanism behind its use with niacin-induced flush. Not NAD+-specific data; reasoned from the shared flushing pathway.

Combinations + timing

Stacking notes + timing windows

NAD+'s rationale is mitochondrial and metabolic — it is the redox carrier and sirtuin/PARP substrate inside the mitochondrion. The best stack partners act on the same energy organelle from a different angle: membrane integrity, signaling, or biogenesis. Pairing NAD+ with its own oral precursor (NR or NMN) pushes the same lever, not a different one — that is substrate stacking, not synergistic stacking.

User combinations reasoned from complementary mitochondrial mechanisms — not pairings studied head-to-head, and NAD+ itself has no controlled outcome evidence, so any stack inherits that uncertainty. Doses are community convention; 'reached for' describes where users go, not a proven indication.

NAD+ + MOTS-c

NAD+ supplies the redox currency; MOTS-c activates the transcription program that rebuilds mitochondrial capacity.

Why it works:: MOTS-c is a mitochondrial-derived peptide that acts as a retrograde signal — it travels from the mitochondria to the nucleus and activates AMPK and FOXO pathways, inducing the cell's own mitochondrial biogenesis (the making of new mitochondria) and metabolic stress-response programs. NAD+ supplies the substrate for the enzymes (sirtuins, PARPs) that are upregulated in that same program. Two different levers on the same organelle: substrate + signaling.
The protocol:: NAD+ 50–100 mg SC once daily in the morning. MOTS-c on its own convention schedule (typically 5–10 mg SC two to three times weekly, or 5 mg daily — community-derived; no human trial). Both injected subcutaneously, different sites, rotated daily.
Outcome:: Reached for on metabolic and longevity-adjacent goals — energy metabolism support, insulin sensitivity, body-composition work. The combination is entirely mechanism-derived; neither compound has strong standalone human outcome data, let alone the combination.

NAD+ + SS-31 (elamipretide)

NAD+ maintains the redox pool; SS-31 targets cardiolipin — the phospholipid that anchors the electron-transport chain to the inner mitochondrial membrane.

Why it works:: SS-31 (elamipretide) is a mitochondria-targeted peptide that binds cardiolipin (a mitochondrial-specific lipid) and stabilizes the inner membrane cristae — the physical structure that houses the electron-transport chain (the chain NADH feeds). When cardiolipin is degraded (as in aging or disease models), electron-transport efficiency drops even with adequate NAD+. SS-31 addresses the structural layer; NAD+ addresses the substrate layer — orthogonal, not redundant.
The protocol:: NAD+ 50–100 mg SC once daily. SS-31 on its studied convention (clinical trials used 0.25–2.5 mg/kg IV; community SC convention runs 5–10 mg SC daily or every other day — much thinner than MOTS-c evidence). Rotate injection sites.
Outcome:: Reached for in biohacking contexts focused on mitochondrial membrane integrity and age-related energy decline. SS-31 has the most clinical trial development of the three mitochondrial peptides listed here, though no completed longevity-indication RCT.

NAD+ + Humanin

NAD+ fuels the metabolic machinery; Humanin provides the mitochondrial-derived cytoprotective signal that helps cells survive metabolic stress.

Why it works:: Humanin is another mitochondrially-encoded peptide, with documented cytoprotective and anti-apoptotic (cell-death-preventing) effects in models of neurodegeneration and metabolic stress. Its signaling runs through the gp130 cytokine receptor and STAT3 pathway — entirely separate from the NAD+/sirtuin/PARP axis. The combination puts a signaling-level survival cue alongside the substrate-level redox support, each a distinct mitochondrial lever.
The protocol:: NAD+ 50–100 mg SC once daily. Humanin on community convention (typically 2–4 mg SC two to three times weekly; no completed human dose-finding trial). Both SC, different sites.
Outcome:: Reached for on longevity, neuroprotection, and metabolic-resilience goals. Humanin blood levels decline with age in humans (published observational data), which is the rationale for supplementation — but that is a biomarker observation, not a clinical outcome trial, and shares the same more-substrate-≠-more-health caveat the whole NAD+ page documents.

Reconstitution math

Reconstitution calculator

Calculated for a 1 mL U-100 insulin syringe (100 units/mL).

Peptide per vial

BAC water added

Desired dose

Units per dose

Draw to this mark on a U-100 syringe

Volume per dose: 0.5 mL
Doses per vial: 2
Concentration: 100 mg/mL

One vial lasts

Daily: 2 days
Every other day: 4 days
5×/week: 2 days

Large draw (50 units). Double-check the vial size and dose — a mcg/mg mix-up produces values like this.

Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.

From the studies

Side effects from research

The best-documented adverse effects of IV NAD+ are infusion-RATE reactions (caused by how fast the drip runs, not the total amount): when given too fast, infusions are associated with flushing (skin warmth and redness), nausea and other gastrointestinal (gut) symptoms, a raised heart rate, and chest tightness/pressure, sometimes with cramping or lightheadedness. A real-world retrospective review found these symptoms forced patients to slow the drip (IV NAD+ infusions took far longer than IV NR for this reason); the symptoms resolved once the infusion finished. In the slow-rate (6-hour) pharmacokinetic pilot, no adverse events were reported — so the reactions are rate-driven, not strictly dose-absolute.

Because infused NAD+ is metabolized to (broken down into) nicotinamide, the safety ceilings for niacin/nicotinamide (forms of vitamin B3) are relevant context. National Academies / NIH set a Tolerable Upper Intake Level (the daily amount considered safe long-term) for niacin at 35 mg/day based on flushing, and chronic gram-level nicotinamide intake has been linked to hepatotoxicity (liver harm). These are oral-intake reference points, not measured limits for infused NAD+, but they bound the conversation.

The honest summary is that the human safety dataset for IV/injectable NAD+ is far too small to characterize real-world risk: a single small PK pilot plus a retrospective tolerability review do not constitute a safety database, and there is essentially no controlled long-term human safety data. This page presents the available literature and makes no therapeutic claim; NAD+ injectables are compounded products, not FDA-approved drugs.

Sources:PMID 31572171 PMID 41704678 NIH ODS

As reported in literature

Research dosing ranges

These are the doses actually used in the published human studies — the evidence the practical patterns above lean on, shown separately so research data is never mistaken for a recommendation or a how-to. The most important distinction is what is being dosed: the strongest data are for ORAL PRECURSORS (NR and NMN), which the body converts toward NAD+; the injectable/IV NAD+ (an infusion into a vein) sold by clinics has only a single small human pharmacokinetic pilot (a study of what a dose does in the body) behind it and no completed efficacy trial. The entries below are reported as evidence only, and this page makes no therapeutic claim. Note that the precursor rows (NR/NMN) are NOT NAD+ itself.

Dose	Route	Model	Outcome	Sources:
750 mg IV over 6 h (~3 µmol/min)	Intravenous	Human — PK pilot (n=11; 8 infused + 3 controls)	No plasma NAD+ rise for the first ~2 h, then +398% by 6 h; large rise in nicotinamide + ADP-ribose (extracellular degradation)	PMID 31572171
100 / 300 / 1000 mg/day, oral, 8 wk	Oral (NR precursor)	Human — RCT (n=140, overweight)	Whole-blood NAD+ rose dose-dependently (+22% / +51% / +142%); well tolerated, no flushing	PMID 31278280
300 / 600 / 900 mg/day, oral, ~60 days	Oral (NMN precursor)	Human — RCT (NCT04823260)	Blood NAD+ rose at all doses; six-minute walk distance improved vs placebo; HOMA-IR unchanged	PMID 36482258
Variable IV infusion (real-world clinic)	Intravenous	Human — retrospective tolerability review	Rate-dependent GI symptoms, raised heart rate, chest pressure during infusion; resolved on completion. Tolerability only — no efficacy outcome	PMID 41704678

Quick answers

Frequently asked

Is NAD+ a peptide?

No. NAD+ (nicotinamide adenine dinucleotide) is a coenzyme — a small dinucleotide molecule made of an adenine half and a nicotinamide half joined by a phosphate bridge. It is grouped in this catalog with the other non-peptides (5-Amino-1MQ, Glutathione, BAC Water). It has no amino-acid sequence.

Does IV NAD+ actually work?

There is no completed, peer-reviewed controlled trial showing that IV or injectable NAD+ produces a clinical health benefit. The direct human evidence is essentially one small pharmacokinetic pilot (what the dose does in the body) plus one retrospective tolerability review. The popular benefits attributed to IV NAD+ are not backed by controlled human outcome data.

What's the difference between NAD+ and NR / NMN?

NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide) are oral PRECURSORS — the body converts them toward NAD+. Almost all of the solid human evidence is for these precursors, not for injected NAD+ itself. In trials they reliably raise the NAD+ level in your blood; what's far less clear is whether that produces a meaningful health benefit.

Do NR and NMN supplements have proven benefits?

They reliably raise blood NAD+ in controlled trials, but the clinical benefit is weak, inconsistent, or null across most human endpoints — an independent review summarized that oral NR has shown 'few clinically relevant effects.' Several of the more positive findings come from trials funded by the companies selling the product, which is a reason to read them cautiously.

Does injected NAD+ get into my cells intact?

Probably mostly not. Cell-surface enzymes (CD38, CD73) break extracellular NAD+ down into precursors before uptake, and the one human IV pharmacokinetic study saw infused NAD+ accompanied by a large rise in its breakdown products — consistent with degradation rather than intact delivery. Vendor claims that IV NAD+ 'floods your cells' overstate what the evidence shows.

Is it true NAD+ drops 50% by age 50?

That specific figure is not backed by a citable controlled human study across tissues — it circulates in marketing and blogs. There IS reasonable evidence (mostly animal, some human tissue) that NAD+ declines with age and that increased consumption by CD38/PARPs drives it, but the precise headline percentages are not primary-source fact.

Primary sources

References

PubChem CID 5892PubChem CID 5892 (NAD+ / nadide; C21H27N7O14P2, MW 663.4; CAS 53-84-9; FDA UNII 0U46U6E8UK)
PubChem CID 439153PubChem CID 439153 (NADH, reduced form; C21H29N7O14P2, MW 665.4)
PMID 31572171Grant et al., Front Aging Neurosci 2019 (only published human IV NAD+ pharmacokinetic pilot; n=11; 750 mg over 6 h; delayed plasma rise + heavy degradation to nicotinamide/ADP-ribose)
PMID 41704678Reyna et al., Front Aging 2026 (retrospective real-world tolerability of IV NAD+ vs IV NR; rate-dependent GI/chest-pressure reactions; tolerability only, not an efficacy trial)
PMID 27721479Trammell, Brenner et al., Nat Commun 2016 (first-in-human NR pharmacokinetics; oral NR dose-dependently raised the blood NAD+ metabolome; PK/biomarker only)
PMID 31278280Conze, Brenner, Kruger et al., Sci Rep 2019 (NR RCT, n=140; whole-blood NAD+ +22%/+51%/+142% at 100/300/1000 mg; ChromaDex-funded — COI)
PMID 37478182Damgaard & Treebak, Sci Adv 2023 (independent critical review: oral NR has shown 'few clinically relevant effects'; no indication oral NR raises muscle NAD+ in humans; warns of exaggeration in the field)
PMID 36482258NMN dose-finding RCT, GeroScience 2023 (NCT04823260; 300/600/900 mg; raised blood NAD+; six-minute walk improved; HOMA-IR unchanged; manufacturer-funded — COI)
DOI 10.1126/science.abe9985Yoshino et al., Science 2021 (NCT03151239; NMN improved muscle insulin sensitivity in prediabetic postmenopausal women; drew a published critique questioning interpretation)
PMID 37994989Orr et al., GeroScience 2024 (NR in mild cognitive impairment; n=20; 2.6-fold blood NAD+ rise but NO cognitive benefit — functional null)
PMC4911708Camacho-Pereira / Chini et al., Cell Metab 2016 (CD38 dictates age-related NAD+ decline and mitochondrial dysfunction via SIRT3; largely mouse + some human adipose)
NIH ODSNIH Office of Dietary Supplements — Niacin (Tolerable Upper Intake Level 35 mg/day based on flushing; chronic gram-level nicotinamide linked to hepatotoxicity)

Research use only · Not medical advice · Updated 2026-06-01