What do NMN and NR do for NAD+ levels?

NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are NAD+ precursors that bypass the rate-limiting NAMPT step in NAD+ biosynthesis, providing a more direct route to NAD+ replenishment. Multiple clinical trials demonstrate that NMN (250 to 1,200 mg daily) and NR (250 to 1,000 mg daily) significantly raise whole blood NAD+ levels in older adults, typically by 40 to 100% within 4 to 8 weeks. Clinical benefits demonstrated in human trials include improved insulin sensitivity, enhanced muscle strength and endurance, reduced inflammatory markers, and improved blood pressure in hypertensive individuals.

What are sirtuins and why do they require NAD+?

Sirtuins (SIRT1 through SIRT7) are NAD+-dependent deacylase enzymes that remove acyl groups from histones and other proteins, regulating gene expression, DNA repair, mitochondrial biogenesis, inflammation, and cellular stress responses. Sirtuins are called longevity genes because their activation extends lifespan in multiple model organisms and their human variants are associated with exceptional longevity. Critically, sirtuins can only function when NAD+ is available: they use NAD+ as a co-substrate to remove acetyl groups. As NAD+ declines with aging, sirtuin activity falls proportionally, impairing all the cellular maintenance processes sirtuins regulate.

How do you raise NAD+ levels?

Evidence-based strategies include: NAD+ precursor supplementation (NMN 250 to 500mg daily or NR 250 to 500mg daily are the most practical options; whole blood NAD+ testing confirms response); regular aerobic exercise (activates AMPK which upregulates NAMPT, the rate-limiting NAD+ biosynthesis enzyme); caloric restriction and intermittent fasting (also activate AMPK-NAMPT pathway); reducing alcohol (depletes NAD+ through alcohol metabolism); reducing inflammation (CD38 on inflammatory cells is a major NAD+ consumer); optimizing vitamin B3 (niacin) intake (niacin is a direct NAD+ precursor but produces flushing at therapeutic doses); and inhibiting CD38 (apigenin and quercetin are natural CD38 inhibitors that may reduce NAD+ consumption).

Lab Reference Library / NAD+ (Nicotinamide Adenine Dinucleotide) Longevity & Aging

NAD+ (Nicotinamide Adenine Dinucleotide)

Q: Why does NAD+ decline with aging?

NAD+ declines with aging through multiple converging mechanisms: increased PARP activation (DNA damage accumulates with aging, continuously activating PARP enzymes that consume NAD+ for repair); increased CD38 expression (CD38 is an NAD+-consuming enzyme expressed on immune cells that rises dramatically with aging and inflammation); reduced expression of NAD+ biosynthesis enzymes (NAMPT, the rate-limiting enzyme converting nicotinamide to NMN, declines with aging); and increased NAD+ consumption by inflammatory signaling (chronic low-grade aging-associated inflammation consumes NAD+ at an accelerated rate). Together these reduce whole blood NAD+ by approximately 50% between ages 30 and 60.

NAD+ · Nicotinamide Adenine Dinucleotide · Whole Blood NAD+

Reference range, optimal functional medicine levels, and why NAD+ is the central molecule of cellular energy metabolism and aging, why it declines 50% or more by middle age, how it drives sirtuin longevity pathways, and why NAD+ precursor supplementation is one of the most evidence-supported longevity interventions.

Longevity MarkerMost Searched

Standard Range20 to 60 µmol/L

FM OptimalAbove 40 µmol/L

Age-Related Decline50% by age 60

Unitsµmol/L

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Category: Longevity & Aging | Also known as: NAD+, Nicotinamide Adenine Dinucleotide, Whole Blood NAD+

1. What This Test Measures

NAD+ (nicotinamide adenine dinucleotide) is measured in whole blood (including intracellular NAD+ from red and white blood cells) because most intracellular NAD+ is destroyed during standard serum preparation. Whole blood NAD+ reflects the body's primary cellular NAD+ pool more accurately than plasma NAD+, which captures only the small extracellular fraction.

NAD+ is the central redox carrier of cellular metabolism, shuttling electrons from metabolic substrates (glucose, fatty acids, amino acids) to the mitochondrial electron transport chain for ATP production. Beyond energy metabolism, NAD+ is the obligate substrate for: sirtuins (SIRT1 to SIRT7, NAD+-dependent longevity enzymes regulating gene expression, DNA repair, mitochondrial biogenesis, and inflammation), PARP enzymes (NAD+-dependent DNA damage repair), and CD38 (NAD+-consuming signaling enzyme on immune cells that rises dramatically with aging). These three enzyme families consume vast amounts of NAD+, and their aggregate demand, combined with declining biosynthesis capacity in aging, produces the 50%+ NAD+ decline between ages 30 and 60.

2. Optimal Range

Whole Blood NAD+	Interpretation
Below 20 µmol/L	Very low: significant NAD+ depletion; sirtuin and PARP function severely impaired
20 to 30 µmol/L	Low: suboptimal; impaired longevity pathway activation
30 to 40 µmol/L	Borderline to adequate: common in middle-aged adults without supplementation
Above 40 µmol/L	Optimal: adequate NAD+ for sirtuin and PARP activity; longevity pathway support
Above 60 µmol/L	Excellent: typically achieved only with consistent NMN or NR supplementation or youth

NAD+ assay standardization is an active area of development; reference ranges vary by laboratory and assay method. Some laboratories report in nmol/mL or other units. Confirm units with your laboratory. Post-supplementation testing should use the same assay platform for meaningful comparison. Fasting is preferred; NAD+ fluctuates with fed-fasted state.

3. Why NAD+ Declines with Aging

PARP hyperactivation: DNA damage accumulates with aging; PARP enzymes consume NAD+ at an accelerating rate for DNA repair, depleting the pool needed for sirtuins and energy metabolism
CD38 upregulation: CD38, an NAD+-consuming enzyme on immune cells and other tissues, increases dramatically with aging and with systemic inflammation (which accompanies aging); CD38 can consume 50 to 100 times more NAD+ than PARP or sirtuins combined in inflamed states
Reduced NAMPT expression: NAMPT (nicotinamide phosphoribosyltransferase) is the rate-limiting enzyme converting nicotinamide (NAM) to NMN and then NAD+; NAMPT expression declines with aging, reducing biosynthesis capacity
Increased inflammatory NAD+ consumption: chronic low-grade aging-associated inflammation activates CD38 and other NAD+-consuming pathways at an accelerating rate
Mitochondrial inefficiency: aging mitochondria produce more superoxide and consume more NAD+ per unit of ATP produced, further depleting the NAD+ pool

4. The Sirtuin-NAD+ Longevity Axis

Sirtuins (SIRT1 to SIRT7) are the primary longevity enzymes that require NAD+ to function. SIRT1 deacetylates histones and FOXO transcription factors, promoting stress resistance, fat oxidation, and inflammation resolution. SIRT3, SIRT4, and SIRT5 are mitochondrial sirtuins that optimize electron transport chain efficiency and reduce oxidative stress. SIRT6 promotes DNA repair and suppresses inflammatory NF-kB signaling. As NAD+ falls with aging, sirtuin activity declines proportionally, impairing all the cellular maintenance processes sirtuins regulate. This is why David Sinclair and others have proposed that NAD+ depletion is an upstream cause of aging rather than merely a consequence of it.

5. NMN vs NR: The Supplementation Choice

NMN (Nicotinamide Mononucleotide)

One step closer to NAD+ than NR; enters cells via the Slc12a8 transporter or is converted to NR extracellularly before cell entry
Multiple human trials demonstrate significant whole blood NAD+ increases (40 to 100%+) at doses of 250 to 1,200mg daily
WASHINGTON trial (2021): 250mg NMN daily for 10 weeks raised blood NAD+ and improved muscle insulin sensitivity in older adults
The most extensively studied longevity compound in humans; David Sinclair's primary research compound
Typical dose: 250 to 500mg daily; sublingually or orally; take with the largest meal

NR (Nicotinamide Riboside)

Commercially the longest-established NAD+ precursor supplement; extensively safety-characterized
Multiple human trials demonstrate NAD+ increases of 40 to 90% at doses of 250 to 1,000mg daily
CHROMADEX/BASIS: 250mg NR twice daily raised whole blood NAD+ by 40 to 51% in healthy middle-aged and older adults
Well-tolerated; no significant adverse effects at recommended doses in published trials
Typical dose: 250 to 500mg twice daily for sustained NAD+ elevation
Both NMN and NR are effective; cost and availability often determine patient choice

6. How to Optimize NAD+ Beyond Supplementation

Increase Production

Regular aerobic exercise: activates AMPK which upregulates NAMPT (the rate-limiting NAD+ biosynthesis enzyme); exercise is the most physiological NAD+-boosting intervention
Caloric restriction and intermittent fasting: activate AMPK-NAMPT pathway; fasting also reduces CD38-driven NAD+ consumption through reduced inflammatory cell activation
Niacin (nicotinic acid): direct NAD+ precursor through the Preiss-Handler pathway; effective for NAD+ elevation but produces flushing at therapeutic doses (above 100mg); niacinamide (nicotinamide) is a precursor but also inhibits sirtuins at high doses
Tryptophan (from dietary protein): converted to NAD+ via the de novo synthesis pathway (kynurenine pathway); adequate dietary protein provides tryptophan substrate

Reduce Consumption

Reduce inflammation: CD38 on inflammatory immune cells is the largest single NAD+ consumer in aged and inflamed states; anti-inflammatory lifestyle interventions preserve NAD+ by reducing CD38 activation
CD38 inhibitors: apigenin (found in parsley, chamomile, celery; 50 to 100mg supplement daily) and quercetin (500mg daily) are the most studied natural CD38 inhibitors; reduce NAD+ consumption without affecting NAD+ synthesis
Reduce alcohol: alcohol metabolism through alcohol dehydrogenase consumes NADH, depleting the NAD+ pool; heavy alcohol use is one of the most impactful NAD+ depleting behaviors
Protect against DNA damage: reducing ultraviolet radiation exposure, environmental toxins, and oxidative stress reduces PARP activation and the associated NAD+ consumption for DNA repair

Testing and Monitoring

Establish baseline whole blood NAD+ before initiating NMN or NR supplementation
Retest at 8 to 12 weeks after starting supplementation to confirm response and adjust dose
Individual response to NAD+ precursors varies 3 to 5-fold; some patients need 500 to 1,000mg NMN daily to move NAD+ meaningfully; others respond dramatically to 250mg
Pair NAD+ testing with GDF-15, klotho, and telomere length for a comprehensive longevity panel that provides a multi-dimensional biological aging assessment
Target whole blood NAD+ above 40 µmol/L; adjust supplementation dose to achieve this target

7. Related Lab Tests

KlothoLongevity Companion Marker; Both Anti-Aging

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GDF-15NAD+ Depletion Drives Mitochondrial GDF-15

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Telomere LengthNAD+ Supports Telomerase Activity

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IGF-1Sirtuin-IGF-1 Longevity Axis Interaction

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hs-CRPInflammation Drives CD38-Mediated NAD+ Depletion

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RBC MagnesiumMagnesium Required for NAMPT and NAD+ Biosynthesis

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8. Clinical Perspective

Clinical Perspective

NAD+ testing made me a believer in longevity medicine as precision rather than philosophy, because I can measure the depletion and I can measure the response to supplementation. When I see a 54-year-old patient with whole blood NAD+ of 18 µmol/L, I know their sirtuins are running on near-empty: inadequate NAD+ to support DNA repair, mitochondrial biogenesis, or inflammatory resolution at anything approaching optimal capacity. Six months of NMN 500mg daily and we recheck: their NAD+ is 47 µmol/L. They report better energy, better sleep, improved exercise recovery. Those are not placebo responses; those are the functional consequences of restoring sirtuin activity in tissues that had been operating in a sub-optimal cellular maintenance state. The measurement makes the intervention credible and the response confirmable, which is exactly what precision medicine requires.

Brian Lamkin, DO | Founder, The Lamkin Clinic | Edmond, Oklahoma

9. Frequently Asked Questions

Why does NAD+ decline with aging?

NAD+ declines through: increased PARP activation (DNA damage accumulates, consuming NAD+ for repair), increased CD38 expression on immune cells (the largest single NAD+ consumer; rises with aging and inflammation), reduced NAMPT enzyme expression (rate-limiting NAD+ biosynthesis enzyme), and increased mitochondrial inefficiency consuming more NAD+ per ATP produced. Together these reduce whole blood NAD+ by approximately 50% between ages 30 and 60.

What is the difference between NMN and NR?

Both NMN and NR are NAD+ precursors that bypass the rate-limiting NAMPT step in NAD+ biosynthesis. NMN is one step closer to NAD+ (NR is converted to NMN before becoming NAD+). Multiple human clinical trials demonstrate that both significantly raise whole blood NAD+ by 40 to 100% at typical doses. Both appear safe and effective; NMN is currently more extensively researched in human trials while NR has the longer commercial availability track record.

What do sirtuins do and why do they require NAD+?

Sirtuins (SIRT1 to SIRT7) are longevity enzymes that regulate gene expression, DNA repair, mitochondrial biogenesis, and inflammation. They extend lifespan in multiple model organisms and are associated with exceptional longevity in humans. Sirtuins use NAD+ as a co-substrate to remove acetyl groups from histones and other proteins; they cannot function without NAD+ present. As NAD+ declines with aging, sirtuin activity falls proportionally, impairing all cellular maintenance processes they regulate.

How long does it take for NMN or NR to raise NAD+ levels?

Whole blood NAD+ responds relatively rapidly: most clinical trials show significant NAD+ elevation within 4 to 8 weeks of consistent supplementation. Retest at 8 to 12 weeks after initiating supplementation to confirm response. Individual variation is significant (3 to 5-fold); some patients need 500mg or more daily to achieve the target above 40 µmol/L; others respond dramatically to 250mg. Target the dose to the measured NAD+ response.

Content authored and clinically reviewed by Brian Lamkin, DO, founder of The Lamkin Clinic in Edmond, Oklahoma. Brian Lamkin, DO has 25+ years of experience in functional and regenerative medicine. This page reflects current functional medicine practice standards and is updated as new clinical evidence becomes available.

NAD+ is the coenzyme that your longevity enzymes run on. By middle age, it has declined by half. That decline can be measured and partially reversed.

NAD+ testing and optimization is precision longevity medicine with measurable biological feedback. Schedule a consultation for a complete longevity biomarker assessment.

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Medical Disclaimer: This content is provided for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Lab interpretation should always be performed in clinical context by a qualified healthcare provider. Reference ranges and optimal targets may vary based on individual patient history, clinical presentation, and laboratory methodology. Schedule a consultation to discuss your specific results with Dr. Lamkin.