NAD+ Levels: How to Increase Them Naturally & With Supplements (2026)

Key Takeaways

• NAD+ declines with age, but the rate varies by tissue and individual. Massudi et al. (2012) measured a roughly linear decline in human skin tissue from age 20 to 77.
• CD38, an immune enzyme that hydrolyzes NAD+, is now considered the primary driver of age-related NAD+ depletion (Camacho-Pereira 2016). Chronic low-grade inflammation raises CD38 expression.
• The most evidence-backed ways to raise NAD+: oral NMN or NR (30+ human RCTs), regular exercise (multiple human studies), and intermittent fasting (limited but positive human data). Lifestyle methods are free but produce smaller increases than supplementation.
• You can measure your NAD+ levels. Companies like Jinfiniti offer intracellular NAD+ testing (optimal range: 40-100 micromoles). This lets you confirm whether your interventions are working rather than guessing from how you feel.

What Are NAD+ Levels and Why Do They Matter?

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every cell of your body. It participates in over 500 enzymatic reactions, including energy production, DNA repair, and gene regulation through sirtuins. Your cells cannot function without it.

"NAD+ levels" refers to the concentration of this coenzyme in your blood, cells, or specific tissues. When researchers and longevity enthusiasts talk about NAD+ levels, they usually mean intracellular NAD+ (the amount inside your cells), which is the concentration that matters for cellular function. Blood NAD+ is a measurable proxy but doesn't perfectly reflect what's happening inside every tissue.

Why levels matter: when NAD+ drops, the enzymes that depend on it can't function at full capacity. Sirtuins slow down (less gene regulation). PARPs work less efficiently (slower DNA repair). Mitochondrial energy production falls (less ATP). This isn't abstract biochemistry. It maps onto the lived experience of aging: declining energy, slower recovery, reduced metabolic flexibility. NAD+ depletion doesn't cause aging by itself, but it's one of the measurable molecular changes that tracks alongside it.

For a full explanation of what NAD+ does and how it works, see What Is NAD+? Benefits, Function & Why It Declines With Age.

NAD+ Levels by Age: How Fast Do They Drop?

The most-cited human data on age-related NAD+ decline comes from Massudi et al. (2012), who measured NAD+ in skin tissue samples from 27 healthy adults aged 20 to 77. They found a roughly linear decline: NAD+ dropped an average of about 10% per decade. By the oldest ages in the sample, tissue NAD+ was approximately half of what it was in the youngest subjects.

A few caveats about this data that get glossed over in supplement marketing. First, it's a small sample (27 people) and measures skin tissue, not blood or brain. NAD+ levels in muscle, liver, and brain may decline at different rates. Second, individual variation is substantial. Some 60-year-olds in the study had higher NAD+ than some 40-year-olds. Genetics, lifestyle, body composition, chronic inflammation, and medication use all affect the trajectory. A blanket "you lose 50% by age 60" oversimplifies what the data actually shows.

What we can say with confidence: NAD+ declines with age in humans, the decline is measurable in multiple tissues, and it accelerates in the presence of chronic inflammation, obesity, and metabolic disease. The decline is real. The exact numbers depend on the individual.

Why NAD+ Levels Decline: The Three Drivers

Understanding why NAD+ drops tells you where to intervene. There are three main drivers, and they're not equally important.

Driver 1: CD38 (the biggest one). CD38 is an enzyme expressed on immune cells and other cell types that hydrolyzes NAD+, breaking it down. Camacho-Pereira et al. (2016, Cell Metabolism) demonstrated that CD38 expression rises with age and that this increase is the primary cause of age-related NAD+ decline in mice, accounting for more NAD+ destruction than PARPs or sirtuins combined. Chronic low-grade inflammation (the kind that comes with aging, obesity, and sedentary lifestyle) drives CD38 upregulation. When your immune system is chronically activated, it burns through your NAD+ supply faster.

Driver 2: PARP activation. PARPs (poly-ADP-ribose polymerases) are DNA repair enzymes that consume NAD+ every time they fix a strand break. As DNA damage accumulates with age and environmental exposure, PARPs work harder and consume more NAD+. This creates a competition for the same NAD+ pool: the more DNA damage you have, the less NAD+ is available for sirtuins and energy production.

Driver 3: NAMPT decline. NAMPT is the rate-limiting enzyme in the NAD+ salvage pathway, which recycles nicotinamide back into NAD+. NAMPT expression drops with age, reducing NAD+ production capacity. Less production + more consumption = declining levels.

These three drivers point to different intervention strategies. Reducing inflammation (exercise, weight management, anti-inflammatory diet) targets CD38. Reducing DNA damage (sun protection, avoiding carcinogens) reduces PARP consumption. Supplementing NAD+ precursors (NMN, NR) bypasses the NAMPT bottleneck by providing substrate directly.

What Actively Depletes Your NAD+ (Beyond Aging)

Age is the slow, inevitable drain. But several lifestyle factors accelerate NAD+ depletion well beyond the baseline 10%-per-decade rate. If you're doing any of these, you're burning through NAD+ faster than your body can make it, regardless of your age.

Alcohol. Every drink you metabolize costs NAD+. Alcohol dehydrogenase, the enzyme that converts ethanol to acetaldehyde, uses NAD+ as a cofactor. One standard drink won't meaningfully dent your NAD+ pool. But habitual drinking (more than 7 drinks per week) creates a chronic draw on hepatic NAD+ that your liver's NAMPT production can't fully compensate for. The liver transplant data is sobering: patients with alcohol-related liver disease had depleted NAD+ and its precursors even after six months of sobriety. The damage to the production machinery takes months to reverse, long after the last drink.

Chronic overeating. Excess caloric intake suppresses NAMPT expression. Twin studies found that the overweight sibling had lower NAMPT gene activity than the lean sibling. Insulin resistance, which develops from sustained caloric surplus, further impairs NAD+ metabolism. This creates a vicious cycle: overeating lowers NAD+, low NAD+ impairs mitochondrial function, impaired mitochondria make weight management harder, and the cycle reinforces itself. Caloric restriction reverses this: it upregulates NAMPT and activates AMPK, both of which boost NAD+ production.

UV radiation and DNA damage. Every time your skin absorbs UV radiation, it generates DNA breaks. Every DNA break activates PARPs. Every PARP activation consumes NAD+. Chronic sun exposure without protection creates a sustained drain on the NAD+ pool in skin and potentially systemically. This connects directly to the ONTRAC trial finding: high-risk skin cancer patients who took nicotinamide (an NAD+ precursor) had 23% fewer new non-melanoma skin cancers. One plausible mechanism is that extra NAD+ allowed PARPs to repair UV-induced DNA damage more effectively.

Chronic stress and poor sleep. Psychological stress activates inflammatory pathways that increase CD38 expression. Poor sleep disrupts the circadian rhythm of NAD+ production (NAD+ normally peaks during the active phase and drops during rest). Shift workers and people with chronic insomnia show metabolic signatures consistent with disrupted NAD+ cycling, though no study has directly measured their NAD+ levels before and after a sleep intervention. What we know from the mechanistic literature is that the circadian clock gene CLOCK directly regulates NAMPT expression. Disrupt the clock, disrupt the enzyme, disrupt NAD+ production.

Chronic inflammation. This is the big one and it loops back to CD38. Any source of sustained inflammation, whether from obesity, autoimmune conditions, chronic infections, or environmental toxins, upregulates CD38 and increases NAD+ consumption. Reducing systemic inflammation through exercise, weight management, anti-inflammatory diet patterns, and (where appropriate) medical treatment of underlying inflammatory conditions is one of the most impactful things you can do to preserve your NAD+ pool. The irony is that many people reach for NAD+ supplements while ignoring the inflammatory fire that's burning through their NAD+ in the first place. Supplements add supply. Reducing inflammation reduces demand. Doing both is more effective than either alone.

NAD+ Levels and Metabolic Health

The relationship between NAD+ and metabolic health runs in both directions, and this is where the "NAD+ levels" conversation becomes personally relevant for a large segment of the population.

Low NAD+ impairs insulin signaling. The Yoshino 2021 trial (Science) showed that NMN supplementation at 250 mg/day improved skeletal muscle insulin sensitivity in overweight postmenopausal women. The mechanism: NAD+ activates SIRT1, which deacetylates insulin receptor substrate proteins and improves downstream signaling. When NAD+ is depleted, this pathway runs at reduced capacity.

Metabolic syndrome depletes NAD+. Obesity increases CD38 expression (more inflammation, more NAD+ consumption), reduces NAMPT expression (less NAD+ production), and creates oxidative stress that further damages the NAD+ biosynthesis machinery. A person with metabolic syndrome is likely losing NAD+ faster than a metabolically healthy person of the same age.

This means people who stand to benefit most from raising NAD+ (those with metabolic dysfunction) are also the ones whose bodies are most aggressively depleting it. Supplementation helps, but it's fighting a headwind. Combining NMN or NR with the metabolic interventions that reduce NAD+ consumption (exercise, caloric management, reduced alcohol) creates a much stronger effect than supplementation alone.

The MIB-626 trial (Pencina et al., 2025, FASEB BioAdvances) tested 2,000 mg/day of NMN in 42 hospitalized patients with COVID-19 and acute kidney injury, a population under severe metabolic stress. Even in that context, NMN safely raised blood NAD+ levels to a peak between days 5 and 14. If NMN can raise NAD+ in critically ill patients, it can raise it in relatively healthy people with metabolic dysfunction. The question, as always, is whether the biomarker change translates to meaningful clinical outcomes. That trial found no difference in kidney injury markers between groups, likely because NAD+ levels rose too slowly relative to the acute disease course.

How to Increase NAD+ Levels Naturally

The interventions below are ranked by evidence strength, not by marketing hype. The ones with published human data come first. The ones with only animal data or theoretical support come later.

Tier 1: Strong Human Evidence

Oral NMN supplementation. Twelve-plus published RCTs. The Christen 2026 trial (Nature Metabolism, 65 participants) showed NMN at 1,000 mg/day roughly doubled blood NAD+ within 14 days. The July 2026 meta-analysis confirmed safety and NAD+ elevation across all tested doses (100-1,250 mg/day). This is the most direct way to raise NAD+: you give the body a precursor molecule that feeds directly into the NAD+ biosynthesis pathway, one enzymatic step from NAD+ itself. Typical cost: $30-60/month. See Best NMN Supplements for product options.

Oral NR supplementation. Twenty-plus published RCTs. Martens et al. (2018, Nature Communications) showed NR at 1,000 mg/day elevated NAD+ metabolites in healthy middle-aged adults. The Christen 2026 trial confirmed NR roughly doubled blood NAD+ at 14 days, comparable to NMN. NR is converted to NMN by NR kinases, then to NAD+. The Berven 2026 pharmacokinetic study found NR raised blood NAD+ more than NMN (161% vs 69%) and reached brain NAD+ after 4 weeks, while NMN did not within the study period. Typical cost: $40-80/month.

Regular exercise. Exercise upregulates NAMPT, the bottleneck enzyme in NAD+ salvage. A 12-week study in sedentary adults found HIIT increased muscle NAD+ by approximately 32% and improved mitochondrial enzyme activity. Lamb et al. (2020, Aging) found that 10 weeks of resistance training twice weekly increased muscle NAD+ by 127% in middle-aged overweight untrained adults, restoring it to levels comparable to trained college-aged participants. The mechanisms are well understood: exercise activates AMPK, which increases NAMPT expression, which increases NAD+ production. Both aerobic and resistance exercise work. Consistency matters more than intensity. 150 minutes per week of moderate activity is the standard recommendation.

Tier 2: Moderate Human Evidence

Intermittent fasting and caloric restriction. Fasting activates AMPK and sirtuins, enhancing NAD+ synthesis and reducing NAD+ consumption. A study found 16:8 intermittent fasting for 8 weeks increased NAD+ by approximately 22% and improved insulin sensitivity. A 58-hour fast increased blood nicotinamide levels by up to 1.7x. Caloric restriction (without malnutrition) is the oldest intervention in longevity research and reliably increases NAD+/NADH ratios in animal models. The human data on fasting and NAD+ is positive but limited to small studies and short durations. Start with 16:8 (skip breakfast, eat noon to 8 PM) if you're new to fasting.

Limiting alcohol. Alcohol metabolism competes directly with NAD+ by consuming it during the conversion of ethanol to acetaldehyde (via alcohol dehydrogenase, which uses NAD+ as a cofactor). Chronic heavy drinking depletes hepatic NAD+ levels. Research on liver transplant patients found that those with alcohol-related liver disease had significantly lower NAD+ and its precursors, even after 6 months of sobriety. Reducing alcohol intake is one of the few interventions that raises NAD+ by reducing consumption rather than increasing production.

Tier 3: Theoretical or Animal-Only Evidence

CD38 inhibitors (quercetin, apigenin, luteolin). CD38 is the main NAD+ consumer. Flavonoids like quercetin, apigenin, and luteolin inhibit CD38 in cell and animal studies. One study suggested quercetin supplementation (500 mg daily) reduced CD38 activity by 35% and increased NAD+ by 18% in older adults, but this finding needs replication in larger trials. Apigenin (found in chamomile and parsley) is the most potent CD38 inhibitor identified in preclinical work. No large-scale human trial has validated any CD38 inhibitor for NAD+ preservation. This is a promising research direction, not a proven strategy.

NAD+-rich foods (tryptophan, niacin sources). NAD+ can be synthesized from tryptophan (the de novo pathway) or from niacin-family compounds in food. Foods naturally high in NAD+ precursors include beef, chicken, fish, mushrooms, edamame, avocado, and green peas. The most-cited food NMN data comes from Mills et al. (2016, Cell Metabolism), who measured concentrations across common foods: edamame 0.47-1.88 mg/100g, broccoli 0.25-1.12 mg/100g, avocado 0.36-1.60 mg/100g, cucumber peel 0.65 mg/100g, and cabbage up to 0.90 mg/100g. Raw beef and shrimp had lower NMN (0.06-0.42 mg/100g) but higher niacin, which feeds NAD+ production through a different pathway.

To put those numbers in perspective: you would need to eat roughly 25 to 50 kilograms of edamame per day to match the 250 to 500 mg of NMN in a single supplement capsule. The amounts in food are measured in micrograms to low milligrams per serving, three orders of magnitude below supplemental doses. Eating a diverse, nutrient-dense diet supports NAD+ production through tryptophan and niacin pathways and provides the B vitamins and minerals that serve as cofactors in NAD+ biosynthesis. But dietary intake alone won't replicate the magnitude of NAD+ increase that supplementation or exercise produces. Think of it as maintaining the foundation while the other interventions build on top of it.

Quality sleep. NAD+ follows a circadian rhythm, peaking during the active phase and declining during rest. Disrupted sleep patterns (shift work, chronic insomnia) are associated with metabolic dysfunction that includes altered NAD+ metabolism. No study has directly measured NAD+ before and after a sleep improvement intervention in humans, so the effect size is unknown. But adequate sleep (7-9 hours, consistent schedule) supports the circadian machinery that NAD+ production depends on.

Heat exposure (sauna). Sauna use activates heat shock proteins and may stimulate NAMPT expression. The evidence is preclinical. Finnish observational studies associate regular sauna use with reduced cardiovascular mortality, but they didn't measure NAD+. Listing sauna as a "NAD booster" (as many articles do) is extrapolation from indirect mechanisms, not from measured NAD+ changes.

How to Test Your NAD+ Levels

"How to test NAD levels" is searched about 150 times per month, which is surprisingly low given how many people are spending money to boost a molecule they've never measured.

Several companies now offer NAD+ testing:

Jinfiniti Precision Medicine offers an intracellular NAD+ test (the Intracellular NAD Test) that measures NAD+ inside your cells, not just in blood plasma. Their published optimal range is 40 to 100 micromoles. The test requires a blood draw (finger prick or venous) and costs approximately $149 to $199 per test. This is currently the most clinically referenced test in the NAD+ supplement space.

ChromaDex TruDiagnostic partnership offers NAD+ measurement as part of a broader aging biomarker panel. This is paired with epigenetic clock testing (biological age estimation).

Some longevity clinics offer NAD+ metabolite panels as part of their standard blood work. These typically measure whole-blood NAD+ plus downstream metabolites (NMN, NR, NAM, ADPR).

Testing before and after an intervention (supplementation, exercise program, fasting protocol) gives you objective data on whether it's working. Testing once is useful for establishing a baseline; testing twice (baseline + 4 to 8 weeks later) is useful for evaluating an intervention. If your post-intervention NAD+ is in the 40 to 100 micromole range and has increased meaningfully from baseline, the intervention is doing what it's supposed to at the biomarker level. If it hasn't changed, either the intervention isn't working, your dose is too low, or your NAD+ wasn't depleted to begin with.

Interpreting Your NAD+ Test Results

Getting a number is easy. Knowing what to do with it is where most people get stuck.

If your intracellular NAD+ is below 40 micromoles (Jinfiniti's suboptimal threshold): you have measurable depletion. This is where supplementation is most clearly warranted. Start at 250-500 mg/day of oral NMN or 300 mg/day of NR. Add exercise if you're not already doing it. Retest in 8 weeks. Most people in this range see a meaningful increase with supplementation alone.

If your NAD+ is between 40 and 70 micromoles: you're in the lower-normal range. Supplementation may help, but the benefit is less certain. This is the range where lifestyle interventions (exercise, fasting, alcohol reduction) may be sufficient without supplements. If you want to try supplementation, 250 mg/day of NMN is a reasonable starting dose. Retest in 8 weeks to see if it moves the needle.

If your NAD+ is above 70 micromoles: you're in the upper-normal range. There's no published evidence that pushing NAD+ higher from this baseline provides additional benefit. Maintaining your current lifestyle and retesting in 6-12 months to confirm stability is a reasonable approach. Spending money on NAD+ supplements when your levels are already optimal is a hard sell from an evidence standpoint.

One common mistake: testing NAD+ once while already taking a supplement and interpreting the result as your "natural" level. If you want a true baseline, test before starting supplementation, or stop supplementation for 2 weeks before testing (NAD+ levels return to baseline relatively quickly after discontinuation). Otherwise, you're measuring the supplement's effect, not your body's native production capacity.

How Long Does It Take to Raise NAD+ Levels?

This depends entirely on the method.

Oral NMN or NR: measurable blood NAD+ increase within days, approximately 2x elevation at 14 days at 1,000 mg/day (Christen 2026). Lower doses (250-500 mg/day) likely take slightly longer to reach the same magnitude.

Exercise: muscle NAD+ increases within 2 to 4 weeks of consistent training. The 127% muscle NAD+ increase from strength training took 12 weeks. Effects are ongoing as long as you keep exercising.

Intermittent fasting: limited data, but the available studies suggest NAD+ improvements within 4 to 8 weeks of consistent fasting.

Alcohol reduction: liver NAD+ recovery may take months, since alcohol-related NAD+ depletion involves structural changes to hepatic metabolism that reverse slowly.

The fastest path: start oral NMN or NR (days to measurable effect). The most durable path: combine supplementation with regular exercise and fasting (synergistic, sustained). The cheapest path: exercise alone (free, 30% increase in 12 weeks).

Stacking Strategies: Combining Methods for Maximum Effect

A 2025 mouse study in Nutrients found that time-restricted fasting combined with NMN supplementation produced larger increases in muscle NAD+ than either intervention alone. The combination also improved mitochondrial ATP production and exercise endurance beyond what either treatment achieved separately. This is a single mouse study, not human data, but the logic holds: fasting upregulates the cellular machinery that converts NMN to NAD+, while NMN provides the raw material. Doing both makes each one work better.

A reasonable human stacking protocol based on available evidence: 250-500 mg oral NMN in the morning + 16:8 intermittent fasting + 150 minutes of exercise per week + 7-9 hours of sleep. Each component targets a different node in the NAD+ system (precursor supply, AMPK activation, NAMPT upregulation, circadian alignment). Total cost: $30-60/month for the NMN; the rest is free.

For detailed dosing guidance on the supplementation component, see NAD+ Dosage: Oral, Injection & IV Dosing Guide.

Supplements vs Natural Methods: The Honest Comparison

Most NAD+ articles frame this as "do both," which is correct but unhelpfully vague. Here's how they actually compare on the numbers.

Oral NMN at 1,000 mg/day roughly doubles blood NAD+ in 14 days. That's the largest, fastest, and most precisely measured effect. It requires swallowing a capsule and spending $30-60/month. The downside: you're dependent on continued supplementation (stop taking it, and levels return to baseline) and the long-term safety data extends only to 12 weeks.

Exercise at 150+ minutes/week increases muscle NAD+ by 30% to 127% over 12 weeks. The increase is slower and more variable, but it comes with cardiovascular, metabolic, muscular, cognitive, and mood benefits that supplements don't provide. The "cost" is time and effort. The unique advantage: exercise may produce more durable NAD+ gains because it structurally upregulates NAMPT, increasing your body's native production capacity rather than just providing external substrate.

Intermittent fasting (16:8) increases NAD+ by roughly 20% in 8 weeks based on limited data. Free, no pills, and carries metabolic benefits similar to caloric restriction. The downside: adherence is hard for many people, the NAD+ data is from small studies, and fasting is contraindicated for some populations (pregnant women, people with eating disorders, type 1 diabetics).

Alcohol reduction's NAD+ effect is harder to quantify because it depends on how much you were drinking. For someone averaging 14+ drinks per week who cuts to 3, the NAD+ recovery is substantial but slow (months of hepatic enzyme normalization). For someone who drinks 3 per week, cutting to 0 may produce a marginal NAD+ change that isn't worth the social friction.

The hierarchy for most healthy adults over 40: start with exercise (the broadest benefits per unit of effort), add fasting if it fits your lifestyle, reduce alcohol if you drink more than moderately, and layer NMN or NR on top if you want the fastest, most measurable NAD+ increase and you're willing to spend the money. Testing before and after tells you which components are moving the needle for you specifically.

What NAD+ Levels Won't Tell You

One caveat that rarely makes it into "boost your NAD+" articles: NAD+ level is a biomarker, not an outcome. Raising it feels like doing something concrete, and the biochemistry supports its importance, but no trial has yet proven that a higher NAD+ number translates directly to living longer, getting fewer diseases, or feeling meaningfully better in a way that outlasts placebo.

The Christen 2026 trial doubled blood NAD+ but didn't measure clinical outcomes beyond 14 days. The Yoshino 2021 trial improved insulin sensitivity (a real outcome) but at a dose that's lower than what most people take. The 2026 PRISMA review covering 113 studies concluded that NAD+ supplementation shows "promise" but stopped short of recommending it as a proven intervention for any specific condition.

This doesn't mean raising NAD+ is pointless. It means the evidence is in the "biologically compelling, clinically preliminary" phase. Measuring your NAD+ and confirming it responds to your interventions is useful. But treating the number as a health report card, where higher always equals healthier, overreads what the current science supports. NAD+ is one piece of a complex metabolic puzzle, not the whole picture.

Frequently Asked Questions

What are normal NAD+ levels?

Jinfiniti's intracellular NAD+ test defines the optimal range as 40 to 100 micromoles. Below 40 is considered suboptimal. No universally standardized reference range exists because testing methodology and tissue type (blood vs intracellular vs muscle) affect the numbers. The Jinfiniti range is the most widely cited in the consumer longevity space.

How to increase NAD+ levels naturally without supplements?

Exercise (150+ minutes/week, including HIIT and strength training) is the most proven non-supplement method. Intermittent fasting (16:8) has positive but limited human data. Limiting alcohol, eating niacin-rich foods, getting adequate sleep, and reducing chronic inflammation all support NAD+ production or reduce its consumption. These methods produce smaller NAD+ increases than supplementation but are free and have broad health benefits.

At what age do NAD+ levels start declining?

Measurable decline begins around age 30 to 40, with an average rate of roughly 10% per decade based on Massudi et al. (2012) skin tissue data. The decline accelerates with obesity, chronic inflammation, and sedentary lifestyle. Individual variation is substantial.

Can you have too much NAD+?

No published human trial has reported adverse effects from NAD+ being elevated "too high" via supplementation. The theoretical concern about excessive NAD+ involves cancer cells (which rely on NAD+ for growth), but this applies to people with existing tumors, not healthy individuals with elevated NAD+. At supplemental doses tested in trials (up to 1,250 mg/day NMN), blood NAD+ roughly doubles; this does not appear to overshoot physiological ranges.

How do I know if my NAD+ levels are low?

You can't tell from symptoms alone. Fatigue, brain fog, and slow recovery are associated with low NAD+ but also with dozens of other conditions. The only reliable way to know is testing (Jinfiniti intracellular NAD+ test or equivalent). If you're over 40 and have never tested, a baseline measurement before starting any NAD+-targeted intervention gives you objective data to work from.

Does exercise really raise NAD+?

Yes. Multiple human studies show exercise increases muscle NAD+ levels. The magnitude depends on exercise type and duration: strength training twice weekly for 12 weeks restored muscle NAD+ to youthful levels in one study. HIIT increased muscle NAD+ by 32% in another. The mechanism is well characterized: exercise activates AMPK, which upregulates NAMPT, the rate-limiting enzyme in NAD+ salvage.

What foods boost NAD+ the most?

Edamame, broccoli, cucumber, cabbage, and avocado have the highest measured NMN content among common foods (0.36 to 1.88 mg per 100g). Foods high in niacin (chicken, turkey, tuna, beef) and tryptophan (turkey, eggs, cheese) support NAD+ production through the de novo and Preiss-Handler pathways. The amounts are far below supplemental doses, but a nutrient-dense diet provides the substrate and cofactors your NAD+ biosynthesis machinery needs to function.

Is it possible to restore NAD+ to youthful levels?

In muscle tissue, yes: Lamb et al. (2020) found 10 weeks of resistance training twice weekly increased muscle NAD+ by 127%, restoring it to levels comparable to trained college-aged adults. In blood, NMN and NR approximately double NAD+ within 14 days. Whether these interventions fully restore NAD+ in all tissues (brain, liver, heart) to youthful concentrations is unknown, as those tissues can't be biopsied in healthy subjects. The Berven 2026 study found oral NR raised brain NAD+ after 4 weeks, which is encouraging but not the same as confirming restoration to youthful levels.

Do NAD+ levels affect how fast you age?

NAD+ depletion is one of the twelve recognized hallmarks of aging (Lopez-Otin et al., 2023, Cell). It's correlated with biological aging, but causation is harder to establish. In animal models, raising NAD+ extends lifespan and healthspan. In humans, the evidence is limited to shorter-term biomarker improvements (insulin sensitivity, NAD+ metabolites, arterial stiffness trends) without lifespan data. No one can yet say "raising NAD+ slows aging in humans" based on completed trials, but the biological plausibility is strong enough that multiple large-scale longevity trials are underway.

Can stress lower NAD+ levels?

Chronic psychological stress activates inflammatory pathways (cortisol, NF-kB, pro-inflammatory cytokines) that increase CD38 expression and NAD+ consumption. Acute stress probably has a negligible effect. The concern is chronic, unmanaged stress that sustains low-grade inflammation for months or years. No study has directly measured NAD+ levels before and after a stress-reduction intervention, but the mechanistic chain from chronic stress to inflammation to CD38 to NAD+ depletion is well-established at each link.

Related Reading

• What Is NAD+? Benefits, Function & Why It Declines With Age
• NAD+ Dosage: Oral, Injection & IV Dosing Guide
• NAD+ Side Effects: What Clinical Trials Report
• Best NMN Supplements in 2026
• Best NAD+ Supplements in 2026
• NAD+ Supplements: Types, Evidence & How to Choose
• Is NAD+ a Peptide? No. Here's What It Actually Is
• ProHealth Longevity NMN Review

References

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Written by Tao Wu. Last reviewed September 2026. This article is for informational purposes and does not constitute medical advice. Talk to your doctor before starting any new supplement or exercise program.