NAD+ Guide: Injections & Precursors

NAD+ became a central longevity molecule for a straightforward reason: every cell spends it. Mitochondria use it to turn food and stored fat into ATP. DNA-repair enzymes spend it during stress. Sirtuins use it to regulate inflammation, circadian timing, and cellular maintenance. How dramatic NAD+ support reads in humans tracks how depleted the pool is and how much demand is on it.

In severe-depletion settings — post-COVID fatigue, chronic illness, alcohol recovery, high training loads — reported improvements in energy, sleep, and cognitive clarity arrive faster on IV and injectable NAD+ than on oral precursors. In healthy populations using NMN or NR as longevity insurance, the signal is slower and quieter: oral precursors raise NAD+ pools, but human lifespan-extension evidence remains thin. A higher number on a lab test is not the same as reversed aging.

The practical case is strongest where depletion is most likely: metabolic support during rapid GLP-1 fat loss (where caloric deficit strains cellular energy production), as the redox currency in the Mito Stack alongside SS-31 and MOTS-c, and for acute recovery after illness or overtraining.

What Is NAD+ and Why Does It Matter?

NAD+ (nicotinamide adenine dinucleotide) is a molecule found in every cell of the body. It's involved in over 500 biochemical reactions — from converting food into energy, to repairing DNA, to regulating the genes that control aging and stress adaptation.

Most articles describe NAD+ as an "energy molecule." That's true but incomplete. NAD+ is better understood as cellular currency — a finite resource that multiple critical systems compete for.

The Competing Demands Framework

The NAD+ pool serves four masters simultaneously:

When the NAD+ pool is full, all four systems run smoothly. Energy is steady. Repair happens in the background. Stress resolves. Inflammation completes its work and shuts off.

When the pool is depleted — from chronic stress, poor sleep, illness, or simple aging — the system begins rationing. Energy becomes fragile. Recovery slows. The mechanisms that maintain long-term cellular stability go quiet because they don't have the fuel to run.

This is why NAD+ depletion doesn't produce a single symptom. It produces a pattern: fatigue, slow recovery, poor stress tolerance, lingering inflammation, and gradual decline in functions that once ran without notice.

Why NAD+ Declines With Age

NAD+ decline isn't random or gradual. It's a self-reinforcing spiral that accelerates over time.

The Numbers

By age 60, most people have lost 50-80% of baseline NAD+ levels. This has been measured across multiple tissues:

The decline isn't linear. It curves downward faster with age because of feedback loops that maintain their own dysfunction.

The CD38 / Senescent Cell Loop

The primary driver of age-related NAD+ decline is immune cells breaking down NAD+ faster than the body can make it. Here's how the loop works:

1. Old cells accumulate — With age, cells that have stopped dividing but refuse to die (senescent cells¹) build up in tissues.

1. Old cells leak inflammatory signals — These signals tell immune cells to activate, as if fighting an infection that isn't there.

1. Immune cells ramp up NAD+ destruction — Macrophages exposed to these signals produce 200-300% more of the enzyme that breaks down NAD+ (CD38²).

1. The drain exceeds production — NAD+ is lost faster than the body can make it.

1. The body's inflammation brakes fail — The enzymes that normally quiet inflammation (sirtuins³) need NAD+ to work. Without it, they go offline.

1. More inflammation → more destruction → lower NAD+ — The loop feeds itself.

This is why the timing of any intervention matters mechanistically: once the spiral has momentum, it is self-reinforcing, and an earlier interruption works against less of it.

Other Factors That Drain NAD+

Beyond the CD38 loop, several factors accelerate NAD+ depletion:

• Constant DNA damage — Under chronic cellular stress (poor sleep, environmental toxins, oxidative load), DNA repair runs 24/7 and burns through NAD+ (PARP overactivation⁴).
• Chronic inflammation — Any inflammatory state increases the enzymes that destroy NAD+.
• Alcohol — Metabolizing alcohol requires NAD+, creating acute depletion.
• Viral illness — SARS-CoV-2 and other viruses trigger multiple NAD+-consuming processes simultaneously.
• Sleep disruption — NAD+ recycling follows circadian patterns. Poor sleep flattens this rhythm (NAMPT regulation⁵).

Foods That Support NAD+ Production

While supplements provide the most direct NAD+ boost, certain foods supply the raw materials for NAD+ synthesis:

Niacin-rich foods (vitamin B3):

• Chicken and turkey breast
• Tuna and salmon
• Peanuts and sunflower seeds
• Mushrooms (especially crimini and portobello)

Tryptophan sources (de novo synthesis):

• Turkey, chicken, eggs
• Dairy products
• Nuts and seeds

Foods with trace NMN:

• Avocado (~0.36-1.6 mg/100g)
• Broccoli (~0.25-1.12 mg/100g)
• Cabbage (~0.0-0.9 mg/100g)
• Beef (~0.06-0.42 mg/100g)
• Edamame (~0.47-1.88 mg/100g)

Reality check: The NMN content in foods is extremely low — roughly 100 kg of broccoli matches the NMN in a single 250mg supplement dose. Diet supports NAD+ maintenance but does not meaningfully restore depleted levels; the supplementation literature addresses that gap.

NAD+ Benefits: What the Research Shows

What the evidence on NAD+ supplementation and therapy supports — organized by strength of evidence rather than marketing claims — breaks down as follows.

Energy and Mitochondrial Function

NAD+ is the electron carrier that makes ATP production possible. When levels are restored:

• ATP production capacity increases
• Mitochondrial efficiency improves
• Oxidative "exhaust" (ROS) decreases

The subjective experience reported isn't stimulation like caffeine. It reads more like baseline capacity returning to where it used to be — steady energy rather than peaks and crashes.

Evidence: Multiple animal studies show NAD+ precursors improve mitochondrial function and exercise capacity. Human trials show improved muscle metabolism, though subjective energy reports are inconsistent (Elhassan 2019).

Cardiovascular Health

One of the more consistent human findings is cardiovascular benefit:

• NR (1000mg/day) reduced systolic blood pressure by 5-10 mmHg in older adults
• Improved arterial dilation and vascular function
• Enhanced nitric oxide production via SIRT1 activation in endothelium

Evidence: Replicated in multiple trials. Effect size comparable to some lifestyle interventions (Martens 2018).

Metabolic Health

• NMN (250mg/day) improved insulin sensitivity in prediabetic women (Yoshino 2021)
• Improved muscle insulin signaling
• Better glucose handling during exercise

Evidence: Small trials, promising but needs replication. Not all metabolic endpoints improve consistently.

Cognitive Function

The brain is one of the most energy-demanding organs. Low NAD+ means neurons can't produce enough ATP.

The NADPARK study was the first to demonstrate that oral NR supplementation increases NAD+ in human brain tissue — measured via magnetic resonance spectroscopy, not just blood levels (Brakedal 2024).

Parkinson's patients showed improvements in some clinical measures, though larger trials are needed.

Evidence: Brain penetration now demonstrated. Clinical benefits still being established. For compounds that use NAD+ to drive neurogenesis directly, see P21.

Sleep and Circadian Rhythm

NAD+ levels naturally oscillate over a 24-hour cycle, regulated by the enzyme NAMPT under circadian clock control. This rhythm helps set the body's internal clock.

When NAD+ levels are chronically low, this oscillation flattens — disrupting sleep architecture and hormonal rhythms. The SIRT1-NAD+-CLOCK/BMAL1 feedback loop that drives this connection is covered in depth in the circadian reset protocol.

Evidence: Mechanistically clear. Anecdotal reports of improved sleep are common but not yet confirmed in controlled trials.

Inflammation Reduction

NAD+ supplementation has shown anti-inflammatory effects:

• NR reduced IL-6 and TNF-α levels in older adults within weeks
• Improved markers correlate with reduced joint pain in some patients
• Mechanism: NAD+-dependent sirtuins restrain NF-κB inflammatory signaling

Evidence: Biomarker improvements are consistent. Symptom improvements are more variable.

Timeline of Effects

Who's Researching NAD+?

NAD+ research isn't fringe or limited to supplement companies. Major academic institutions and federal agencies have dedicated programs.

National Institutes of Health (NIH)

• Federal NAD+ research hub — Studies mitochondrial dysfunction, DNA repair, immune aging, and NAD-dependent stress pathways
• RECOVER Consortium — NIH-led Long COVID program evaluating metabolism, inflammation, and NAD-related mechanisms
• Key researchers: Evandro Fang, Ph.D., Mark Mattson, Ph.D.

Harvard Medical School

• Paul F. Glenn Center for Biology of Aging — Dedicated aging research center
• David Sinclair's lab has published extensively on age-related NAD+ decline, sirtuin regulation, and NMN research
• Focus: NAD+, neurodegeneration, stress adaptation

Washington University in St. Louis

• Shin-ichiro Imai, M.D., Ph.D. — Studies NAMPT regulation, NAD+ circadian oscillations, and tissue aging
• Discovered eNAMPT (extracellular NAMPT) as a circulating NAD+ regulator
• Core hub for mechanistic NAD+ aging studies

Mayo Clinic

• Eduardo Chini's lab — Identified CD38 as the major driver of age-related NAD+ decline
• Established the senescent cell → CD38 → NAD+ depletion connection
• Research on NAD+ and cellular senescence

Stanford University

• Center on Longevity — Examines metabolic and immune pathways intersecting with NAD+
• Michael Snyder, Ph.D., has mapped molecular "inflection points" in human aging, including NAD+ pathways
• NAD+ biosynthesis and immune function research

University of Bergen / Haukeland Hospital (Norway)

• NADPARK Study — First randomized controlled trial demonstrating NAD+ augmentation in human brain tissue
• Led by Charalampos Tzoulis, M.D., Ph.D.
• First direct evidence that oral supplementation reaches the brain

University of Iowa

• Charles Brenner, Ph.D. — Discovered nicotinamide riboside (NR) as an NAD+ precursor in 2004
• Foundational work enabling nearly all subsequent NR clinical trials
• Scientific advisor to ChromaDex (Niagen manufacturer)

Active Clinical Trials (U.S.-Based)

Long COVID and NAD+: The Clinical Proof Point

The relationship between NAD+ and Long COVID may be the strongest clinical validation of NAD+ biology to date. The mechanism is clear, and trials are underway.

The Mechanism

SARS-CoV-2 leaves behind a specific metabolic signature: persistent collapse of NAD+ economy within immune, neural, and metabolic tissues.

During acute infection, multiple NAD+-consuming processes activate simultaneously:

1. PARP activation — Viral RNA triggers DNA repair enzymes that burn through NAD+
2. CD38 upregulation — Inflammatory macrophages express more NADase activity
3. Kynurenine pathway diversion — Tryptophan gets diverted away from NAD+ synthesis

The combined result: Sharp, sudden NAD+ depletion. Most patients recover. A subset do not.

The Self-Sustaining Loop

Once NAD+ falls below a critical threshold, the system can't recover on its own:

• Inflammation brakes fail — The enzymes that quiet inflammatory signaling need NAD+ to work. Without it, the alarm keeps ringing (sirtuin-NF-κB axis⁶).
• New mitochondria stop being built — The signals for mitochondrial growth require NAD+. Production stalls (SIRT3/PGC-1α⁷).
• Daily NAD+ rhythm flattens — NAD+ normally rises and falls with the circadian cycle. That oscillation disappears.
• Each dysfunction reinforces the others — Low NAD+ causes inflammation, which destroys more NAD+.

This is why Long COVID often resembles accelerated aging compressed into months: the same NAD+-driven systems that erode slowly over decades are disrupted abruptly.

Clinical Evidence

• 52% responder rate in a pilot trial (n=36) using NAD+ patches + low-dose naltrexone — promising but needs larger replication
• MGH RECOVER initiative evaluating NAD-related pathways as contributors to persistent symptoms
• Mass General Brigham RCT testing high-dose NR for cognitive recovery and quality of life

A 2022 study directly demonstrated that SARS-CoV-2 suppresses NAMPT and NMNAT — the essential genes for NAD+ salvage — while simultaneously inducing PARP family genes. When NAD+ or NMN was administered, mitochondrial respiration and metabolic coherence improved (Jiang 2022).

Practical Implications

NAD+ restoration for Long COVID is not about treating the infection — it's about breaking the metabolic trap that sustains dysfunction. Raising the NAD+ floor restores the enabling conditions for other systems to recover.

How to Restore NAD+: Injections, IV Therapy, and Supplements

There are three primary approaches to raising NAD+ levels, each with distinct advantages.

Oral Precursors: NMN vs NR

Both NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are NAD+ precursors — molecules the body converts into NAD+ through natural pathways.

Important note: No head-to-head human trial comparing NR vs NMN exists. Both can raise NAD+ biology. The "fewer steps" argument for NMN is simplified — absorption, digestion, conversion to NR or nicotinamide, and tissue uptake matter as much as the diagram on a label.

Tissue preferences:

What oral supplements show in the data:

• Gradual NAD+ elevation (not immediate)
• Effects typically plateau at 600mg NMN or 1000mg NR — higher doses don't seem to help more
• Adverse events are limited to mild GI upset at high doses
• Effects plateau at 4-8 weeks (suggesting tissue saturation)

NAD IV Therapy

Intravenous NAD+ bypasses digestion and infuses NAD+ into the bloodstream under clinical supervision.

Key pharmacokinetic insight (Grant et al. 2019):

When 750mg NAD+ is infused over 6 hours:

• No plasma rise until >2 hours despite continuous infusion
• This indicates rapid tissue uptake during the first 2 hours
• Peak elevation: 398% above baseline at 6 hours
• Metabolites peak: NAM +409%, NMN +472% at 8 hours

Practical implication: IV NAD+ is essentially a slow-release delivery system for nicotinamide and other metabolites. The NAD+ itself is rapidly consumed or converted.

Typical protocols:

• 500-1000 mg per session, infused over 2-4 hours
• Loading series: 4-5 sessions over 2 weeks
• Side effects if infused too fast: nausea, chest tightness, flushing
• Must be administered in clinical setting

NAD Injections: IM and SC Routes

Intramuscular (IM) and subcutaneous (SC) NAD injections offer a middle ground between oral and IV routes.

IM NAD Injection:

• 50-250 mg per injection
• Commonly 2-3 times weekly during active rebuilds, then weekly for maintenance
• The route most often used at-home for larger or more active support doses
• Slower release than IV, fewer acute symptoms
• Self-administered after initial supervision in most at-home protocols
• Slow administration and dilution matter because NAD+ solutions can sting

SC NAD Injection:

• 25-100 mg per injection
• Several times weekly, or split into smaller doses if irritation dominates
• Slower shallow-depot exposure, but often more sting and local welting than IM
• Used when IM is not an option, less common than IM for larger doses

Note: Formal pharmacokinetic studies for IM and SC NAD+ are extremely limited. Dosing protocols are based on clinical observation rather than rigorous trials.

Why NAD+ Injections Burn (And How to Reduce It)

If you've injected NAD+ subcutaneously, you already know: it burns. This isn't technique error or bad product — it's chemistry.

The cause: NAD+ is inherently acidic. Reconstituted NAD+ has a pH around 3.5–4.0, far below your tissue's neutral pH of ~7.4. When acidic solution contacts subcutaneous tissue, it triggers immediate pain signaling. The burn typically peaks within 30 seconds and fades over 5–15 minutes.

This is universal. Every NAD+ injection will have some degree of sting. The question is how much, and what reduces it.

Dose-Pain Relationship

Higher concentration = more burn. This is counterintuitive if you're trying to minimize injection volume, but it's consistent across user reports:

If you're experiencing intolerable pain, the first step is reducing dose per injection. Two 50 mg injections usually burn less than one 100 mg injection, even though total dose is the same. This is especially true for SubQ use.

Buffered NAD+ reduces the sting

NAD+ stings mainly because it is acidic, so a higher-pH formulation is what reduces the burn. The preference is to buy a buffered version of NAD+, which is formulated at a higher pH, so source it pre-buffered when it is supplied or prescribed for the product. Reconstitute it with BAC water containing sodium chloride (NaCl) to ease the welting; NaCl helps the osmotic side of the discomfort but does not correct the acidity.

Do not mix your own buffer into the syringe. Home-buffering changes the solution chemistry, there is no pharmacokinetic dataset for buffered at-home NAD+, and a buffered preparation should be used promptly. Buy a buffered product rather than improvising, start with smaller volumes, and assess tolerance.

Injection Site Matters

Not all sites burn equally. Based on community reports from r/NicotinamideRiboside and r/Peptides:

• Love handles (lateral hip): Fat pad absorbs slowly; fewer nerve endings
• Outer thigh: Good for larger volumes
• Abdomen: More vascular; faster uptake but more sting
• Inner arm: Thin tissue; not recommended

Rotate within your preferred zone. Don't inject the same spot repeatedly — this causes localized irritation and can form persistent lumps.

Technique Factors

• Injection speed: Slow injection (30–60 seconds for 1 mL) distributes the acidic load across more tissue, reducing peak pain
• Temperature: Room temperature solution stings less than cold. Let it sit 10–15 minutes after removing from refrigerator
• Needle gauge: 27–30g is standard for SubQ. Smaller gauge = less tissue trauma but slower injection
• Depth: Deeper SubQ (into fat pad, not just under skin) reduces surface nerve activation

When Burning Is NOT Normal

Typical NAD+ burn fades within 15 minutes. Seek medical attention if:

• Pain persists beyond 30 minutes or intensifies
• Redness spreads beyond the immediate injection site
• You develop hives, facial swelling, or difficulty breathing (allergic reaction)
• Hard lumps persist for more than 7 days
• Fever develops

These suggest either allergic response, infection, or contamination — not normal pH-related discomfort.

IM as Alternative

If SubQ burning is intolerable despite mitigation, consider intramuscular (IM) injection. IM deposits NAD+ into muscle tissue, which is often less reactive than a shallow SubQ depot. For this reason, IM is the preferred at-home route for active NAD+ rebuilds, while SubQ is the acceptable fallback when doses are kept smaller and split.

How Routes Map to Use Case

Cost Considerations

• Oral NMN/NR: Varies by brand and dose
• IM NAD+: 2-4 injections weekly
• SC NAD+: Daily microdosing
• IV NAD+: Clinical setting required
• IV loading (5 sessions): Initial intensive phase

Insurance does not cover NAD+ therapy. IM/SC self-administration also requires supplies and initial clinical training. See the reconstitution guide for preparation details.

Combined Approach (Severe Depletion)

1. Weeks 1-4: IM 100-250 mg 2-3× weekly, or clinic IV loading where depletion is severe and supervision is available
2. During loading: oral NR or NMN runs alongside at a conservative daily dose
3. Weeks 4-8: IM continues 1-2× weekly where the response is clear; otherwise the protocol transitions toward oral maintenance
4. Week 8+: IM 50-150 mg weekly or as needed, with oral daily maintenance where it adds

For peptide dosing calculations and reconstitution volumes, use the peptide calculator.

Does NAD+ Actually Work? Evidence Assessment

The evidence varies by category.

Well-Established (Multiple Human RCTs)

• NAD+ precursors raise blood NAD+ levels — consistent across all trials
• NR improves blood pressure in older adults (5-10 mmHg reduction)
• No serious adverse events at doses up to 2g/day in any trial reported to date
• NR increases brain NAD+ — demonstrated via MRS in NADPARK study

Emerging (Small Trials, Promising)

• NMN improves insulin sensitivity in prediabetic women
• NAD+ + LDN combination shows 52% responder rate for Long COVID fatigue
• Improved muscle function and exercise capacity in older adults
• Anti-inflammatory effects (reduced IL-6, TNF-α)

Mechanistically Sound (Not Yet Proven in Humans)

• NAD+ supports the redox pool GLP-1 users spend during fat oxidation and caloric deficit
• CD38 inhibitors preserve NAD+ (animal data only, no human trials)
• Long-term supplementation extends healthspan (mouse lifespan data)

What We Don't Know

• Multi-year safety data — maximum trial duration is ~12 weeks
• Whether blood NAD+ reflects tissue levels — especially brain
• Optimal precursor — no NR vs NMN head-to-head human trial
• Long-term cancer risk — theoretical concern, no signal in trials

Who Responds Best

People most likely to benefit from NAD+ restoration:

• Those with chronic fatigue or post-viral illness
• People over 40 with declining energy
• Those with high inflammation or autoimmune conditions
• People who've hit plateaus with other protocols
• Those recovering from injury or illness

People less likely to notice dramatic effects:

• Young, healthy individuals with good NAD+ levels already
• Those whose issues aren't related to cellular energy or inflammation

NAD+ Safety and Contraindications

Oral Supplements (NMN/NR)

In studies up to 1-2 grams per day, the observed adverse-event profile is limited:

• Most common: mild GI upset at high doses
• No serious adverse events in clinical trials
• No liver toxicity or organ damage observed

IV NAD+

Side effects are rate-dependent (happen if infused too fast):

• Nausea
• Abdominal cramping
• Chest tightness or pressure
• Lightheadedness

These resolve when the infusion slows. No serious adverse events have been reported in medical literature from pure NAD+ infusions — but the cardiovascular load is real, and the evidence base in vulnerable populations is thin. Heart failure, a significant arrhythmia history, and low cardiac reserve are the profiles where IV NAD+ carries the most uncertainty; in those profiles cardiology clearance gates the start, and oral NMN/NR carries a lower load. The injectable route is one path among several, and not the first one against a cardiac history.

Absolute Contraindications

Caution Required

The Cancer Question

NAD+ supports cell growth and DNA repair. Cancer cells also need these things. This creates theoretical concern but no actual signal in human data:

• One mouse study suggested high-dose NR might accelerate existing triple-negative breast cancer spread — but the dose was 6.6x higher than typical human doses, sample sizes were tiny, and statistical significance was p=0.52 (not significant)
• No increased cancer rates in any human NAD+ trial
• Some evidence that NAD+ may actually protect against cancer by improving DNA repair

Where the line sits: active cancer contraindicates NAD+ supplementation; a prior cancer history routes through an oncologist before any use.

FAQ

NAD+ and Peptide Integration

For those using peptide therapies, NAD+ provides the foundational capacity that allows peptides to execute their instructions.

Why Peptides Need NAD+

Peptides are signaling molecules — they tell cells what to do. But execution requires energy:

• GLP-1 agonists (semaglutide, tirzepatide, retatrutide) create a deficit and push the body to use stored fuel. NAD+ is required for the redox steps that turn mobilized fat into ATP. Without enough NAD+ capacity, fat can be released but oxidation feels fragile. Injectable L-Carnitine is the transport partner, shuttling fatty acids into mitochondria where NAD+ supports the burn. Learn more about GLP-1 therapy →

• Healing peptides (BPC-157, TB-500) signal repair, but repair is energy-intensive. Without NAD+, signals arrive but execution falters. NAD+ and healing →

• Anti-aging peptides activate maintenance programs that depend on sirtuins — which require NAD+ to function. NAD+ and aging →

• Mitochondrial peptides (SS-31, MOTS-c) improve energy machinery, but machinery needs NAD+ to run. The MITT Stack →

High-signal interventions on a depleted base produce partial, fragile improvements. On a repleted base, they produce durable change.

Related Topics

• Mitochondrial Stack White Paper — comprehensive overview of mitochondrial support peptides including NAD+ strategies
• SS-31 Guide — cardiolipin-stabilizing peptide that protects mitochondrial membrane function
• MOTS-c Guide — mitochondrial-encoded peptide that coordinates cellular energy metabolism
• Pinealon Guide — neuroprotective tripeptide that supports cognitive function and circadian regulation
• Mitochondrial peptides + GLP-1 — how to combine NAD+ restoration with metabolic peptides
• Why GLP-1 Medications Make You Tired — NAD+ depletion is a key driver of the months 3-6 fatigue wall
• TB-500 Guide — Repair peptide whose healing work is energy-intensive — needs NAD+
• Immune Peptide Protocol — NAD+ is the Phase 1 foundation for immune reconstitution
• Injury Recovery Protocol — NAD+ fuels the cellular energy every repair process runs on
• Where to Inject Peptides — NAD+ injection routes, why it burns, and how to fix it

References

Mechanism Notes

¹ Senescent cells — Cells that have exited the cell cycle but resist apoptosis; accumulate with age and secrete pro-inflammatory factors (SASP): Covarrubias 2020

² CD38 — NADase enzyme on immune cells; primary driver of age-related NAD+ decline; upregulated by inflammatory cytokines: Camacho-Pereira 2016

³ Sirtuins — NAD+-dependent deacetylases (SIRT1-7); regulate metabolism, stress response, and inflammation; restrain NF-κB signaling: Yoshino 2021

⁴ PARP overactivation — Poly(ADP-ribose) polymerase enzymes consume NAD+ during DNA repair; chronic activation depletes pools: Covarrubias 2020

⁵ NAMPT regulation — Nicotinamide phosphoribosyltransferase; rate-limiting enzyme in NAD+ salvage pathway; circadian-regulated: Yoshino 2021

⁶ Sirtuin-NF-κB axis — SIRT1 deacetylates NF-κB p65 subunit, suppressing inflammatory gene transcription; NAD+ depletion releases this brake: Covarrubias 2020

⁷ SIRT3/PGC-1α — SIRT3 (mitochondrial sirtuin) and PGC-1α coordinate mitochondrial biogenesis; both require adequate NAD+: Yoshino 2021

Sources

¹ Covarrubias AJ, et al. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology (2020).
² Camacho-Pereira J, et al. CD38 dictates age-related NAD decline and mitochondrial dysfunction. Cell Metabolism (2016).
³ Yoshino J, et al. NAD+ intermediates: The biology and therapeutic potential. Nature Aging (2021).
⁴ Brakedal B, et al. NR increases brain NAD+ in Parkinson's disease. Nature Communications (2024).
⁵ Yoshino M, et al. NMN increases muscle insulin sensitivity in prediabetic women. Science (2021).
⁶ Martens CR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+. Nature Communications (2018).
⁷ Grant R, et al. Pharmacokinetics of intravenous NAD+ in humans. Redox Biology (2019).
⁸ Freeberg KA, et al. NAD+ precursor supplementation: safety considerations. American Journal of Physiology - Endocrinology and Metabolism (2023).
⁹ Elhassan YS, et al. Nicotinamide riboside augments the aged human skeletal muscle NAD+ metabolome. Cell Reports (2019).
¹⁰ McReynolds MR, et al. NAD+ decline is causally linked to loss of metabolic health during aging. GeroScience (2022).
¹¹ Jiang C, et al. NAD+/NMN rescue of SARS-CoV-2-induced metabolic dysfunction. Cell Discovery (2022).
¹² Covarrubias AJ, et al. Senescent cells promote tissue NAD+ decline via CD38+ macrophages. Nature Metabolism (2020).

Foundational Reviews

¹³ Covarrubias AJ, Perrone R, et al. "NAD+ metabolism and its roles in cellular processes during ageing." Nat Rev Mol Cell Biol. 2021. PMID 30653609
¹⁴ de Picciotto NE, Gano LB, et al. "Nicotinamide mononucleotide supplementation reverses vascular dysfunction." Aging Cell. 2016. PMID 29514064
¹⁵ Verdin E. "NAD+ in aging, metabolism, and neurodegeneration." Science. 2015. PMID 24360282