NAD+ Side Effects: What Clinical Trials Report (2026)

Key Takeaways

• Oral NMN and NR are the most studied NAD+ delivery methods. No serious adverse events have been attributed to either in any published trial.
• Side effects differ sharply by delivery method. Oral: mild GI issues. IV: chest tightness and nausea (dose-rate dependent). Injection: site stinging. Nasal spray and patches: limited safety data.
• The cancer question is real but unresolved. Tumors overexpress NAMPT (the NAD+-building enzyme) and rely on NAD+ for growth. In mice, NMN accelerated pancreatic cancer. In humans, no trial has shown increased cancer risk from NAD+ precursors, but no trial was designed to test for it either.
• People with active cancer, autoimmune conditions, or taking NAMPT-pathway drugs should talk to their doctor before using any NAD+ product.

Oral NMN Side Effects: What Clinical Trials Report

This is where the evidence is deepest, so start here.

The July 2026 systematic review and meta-analysis published in Nutrients searched six databases through May 2026 and pooled data from all eligible parallel-group NMN RCTs. Their safety analysis found no statistically significant difference in adverse event rates between NMN groups and placebo groups. No serious adverse events were attributed to NMN at any dose tested, which ranged from 100 to 1,250 mg per day across trial durations of 4 to 12 weeks.

The earlier Zhang et al. 2024 meta-analysis in Critical Reviews in Food Science and Nutrition covered 12 RCTs with 513 total participants and came to the same conclusion on safety. They noted that the side effects reported were "mild to moderate" and consistent with the low incidence of side effects found in a prior systematic review of NAD across clinical conditions (Gindri et al., 2023, American Journal of Physiology).

What "mild to moderate" actually means in practice:

One thing the meta-analyses can't tell you: whether side effects emerge beyond 12 weeks. The longest NMN trial to date ran 12 weeks. No published study has tracked NMN supplementation for six months or a year. That doesn't mean long-term use is unsafe. It means we genuinely don't know yet, and anyone claiming long-term safety data exists is getting ahead of the evidence.

NR (Nicotinamide Riboside) Side Effects

NR has a longer clinical history than NMN, with over 20 published human trials. The safety profile looks similar: well tolerated, no serious adverse events attributed across the studied dose range (100 to 2,000 mg/day). The most commonly noted side effect is mild GI discomfort, same as NMN.

The Gindri et al. 2023 systematic review in American Journal of Physiology examined RCTs of NAD, NAD+, NADH, NR, and NMN administered orally at various dosages in humans aged 18 to 70. They concluded that NAD and its precursors have "a low incidence of side effects" across the studied conditions.

One notable finding from the February 2026 Berven et al. pharmacokinetic study (iScience): NR raised blood NAD+ substantially more than NMN in that trial (roughly 161% vs 69%), which raises the theoretical question of whether higher NAD+ elevation correlates with more side effects. In that study, it did not. Both groups reported similar and minimal adverse events. But if future studies replicate the finding that NR produces a larger NAD+ spike, the safety comparison may need revisiting with larger sample sizes.

IV NAD+ Infusion Side Effects

This is where the side-effect conversation changes tone. IV NAD+ hits the bloodstream directly and at much higher concentrations than oral precursors produce, so the reactions are more noticeable.

Commonly reported during or immediately after IV NAD+ sessions:

• Chest tightness or a sensation of pressure in the chest
• Nausea, sometimes progressing to vomiting
• Headache
• Muscle cramping, particularly in the legs
• Dizziness
• A sensation of heat or warmth spreading through the body

These are dose-rate dependent. Slowing the drip rate typically reduces or eliminates symptoms. Most clinics start with a slow infusion (over 2 to 4 hours for a 500 mg dose) and adjust based on how the patient responds. The reactions resolve after the infusion ends and do not persist.

A critical gap in the evidence: despite widespread clinical use, no published randomized controlled trial has systematically characterized IV NAD+ side effects with standardized outcome measures. What we know comes from clinician and patient reports at wellness clinics, not from controlled research. A 2024 pilot study of IV NR (Niagen IV, ChromaDex) noted that systematic safety investigations of IV NAD+ "remain limited despite its widespread use." That quote tells you everything about the evidence quality here.

For more on what IV sessions involve and cost, see NAD+ IV Therapy: How It Works, Costs & Evidence.

Subcutaneous NAD+ Injection Side Effects

Subcutaneous NAD+ (injected into the fat layer, typically the abdomen or thigh) produces a different set of reactions than IV.

• Stinging or burning at the injection site (the most universally reported effect)
• Brief nausea (less common than with IV, likely because the absorption is slower)
• Redness or swelling at the injection site

These are self-limiting. The stinging is partly pH-related; buffered NAD+ formulations (adjusted to physiological pH) tend to cause less discomfort than unbuffered preparations.

Same evidence gap as IV, with one recent exception: in April 2026, a preprint (Nkrumah-Elie et al., not yet peer-reviewed, funded by ChromaDex) reported the first Phase 1 pilot safety data on injectable NR and NAD+. Trial 1 randomized 45 participants across intramuscular, intravenous, and subcutaneous routes for placebo, NR, and NAD+. This is the first systematic human injection safety data, but it's preliminary, industry-funded, and awaiting peer review. Beyond this, everything known comes from telehealth providers and compounding pharmacy clinical experience, not controlled trials.

For a breakdown of injection methods and costs, see NAD+ Injections: Benefits, Side Effects & Cost.

NAD+ Nasal Spray Side Effects

NAD+ nasal sprays are one of the newer delivery methods. Published safety data is thin.

Anecdotally reported side effects include nasal irritation, a burning sensation in the nasal passages, and headache. No published clinical trial has tested a NAD+ nasal spray formulation in a controlled setting, so there is no formal adverse-event data to cite. This delivery route remains experimental in practice.

NAD+ Patches Side Effects

Transdermal NAD+ patches are marketed as a slow-release delivery system. Like nasal sprays, clinical evidence for patches is essentially nonexistent in published literature.

User-reported side effects include skin irritation or redness at the patch site and adhesive-related reactions. Whether the NAD+ in these patches achieves meaningful systemic absorption is itself unproven, which makes the side-effect question somewhat moot: if the molecule isn't getting through the skin in significant amounts, you're mainly evaluating the side effects of the adhesive.

NAD+ and Liver Function

The July 2026 NMN meta-analysis specifically tracked liver enzymes (ALT and AST) as safety endpoints across pooled trial data. These enzymes are the standard clinical markers for liver stress or damage, and they matter because NMN is metabolized partly in the liver through the salvage pathway.

The result: NMN supplementation did not cause clinically meaningful changes in ALT or AST levels compared to placebo groups. This is reassuring, particularly for people who take other supplements or medications that are processed by the liver. But the same caveat applies: trial durations maxed out at 12 weeks. Whether NMN at 500+ mg/day for six months or a year affects liver enzymes is genuinely unknown.

For comparison, high-dose niacin (the traditional form of vitamin B3) is well documented to raise liver enzymes in some patients, particularly at sustained-release doses above 2,000 mg/day. NMN and NR have not shown this effect at their studied doses, which suggests a different hepatic handling profile. But if you have pre-existing liver disease or are taking hepatotoxic medications (statins, acetaminophen at high doses, certain antiretrovirals), extra caution and physician monitoring are warranted when adding any supplement that runs through hepatic metabolism.

What Dose Is Safe? What the Trials Actually Tested

People want a number. Here's what the published evidence supports, by molecule and delivery method.

A dose being "tested" does not mean it has been proven safe for long-term use. It means no serious adverse events were observed during the trial period at that dose. The maximum tested dose of NMN (1,250 mg/day) was used in a single trial. Most NMN studies cluster around 250 to 600 mg/day. If you're starting out, beginning at the lower end of the studied range (250 mg/day) and increasing gradually is the approach most aligned with the available evidence.

One practical detail about oral NMN that the trials don't always make clear: taking NMN on an empty stomach seems to produce more GI discomfort than taking it with food. This hasn't been formally studied in an RCT comparing fed vs fasted administration, but clinical pharmacists and several trial protocols note it. If you experience nausea or stomach upset, try taking your NMN with breakfast rather than on an empty stomach before adjusting your dose down.

NAD+ and Cancer Risk: The Honest Answer

This is the side effect question that actually matters, and the one where a supplement brand telling you "NAD+ is totally safe" should make you pause.

Cancer cells are metabolically ravenous. They need enormous amounts of energy to sustain their rapid division. To get that energy, many tumors upregulate NAMPT, the enzyme that builds NAD+ through the salvage pathway. High NAMPT expression in tumors is linked to more aggressive cancers, worse survival outcomes, deeper tissue invasion, and resistance to certain chemotherapy drugs. This is well-documented across glioblastoma, pancreatic cancer, prostate cancer, ovarian cancer, colorectal cancer, breast cancer, and myeloma.

The therapeutic implication: oncology researchers have been trying to starve tumors by depleting NAD+. Drugs called NAMPT inhibitors (FK866, CHS 828, OT-82) went into phase I cancer trials specifically to cut off the NAD+ supply to tumors. That's the opposite of what NAD+ supplementation does.

So the question is straightforward: if you raise NAD+ levels through supplementation, could you be feeding a tumor you don't know you have?

What the evidence says:

In mice, giving NMN to animals with pancreatic cancer accelerated the progression of the cancer, apparently by aggravating inflammation (Greger, 2025). That's a single mouse model, and mouse pancreatic cancer biology doesn't translate directly to humans, but it's a data point that can't be dismissed.

In humans, the picture is different so far. No published clinical trial of NMN or NR has reported increased cancer incidence in supplementation groups. A 2025 veterans' cohort study found lower rates of keratinocyte (skin) cancers with nicotinamide use. The ONTRAC trial showed that high-dose nicotinamide reduced new non-melanoma skin cancers in high-risk patients by 23%. These are niacin-family compounds, not NMN or NR specifically, but they belong to the same B3 family of NAD+ precursors.

The honest assessment as of September 2026: no human evidence that NAD+ precursors increase cancer risk, but also no trial designed to test for it. Every existing trial measured NAD+ elevation and metabolic endpoints, not cancer incidence. The follow-up periods (4 to 12 weeks) are far too short to detect cancer development. We won't have a real answer until large, long-term trials with cancer endpoints are completed.

What this means practically: if you are a healthy adult with no active cancer and no strong family history of cancer, the current evidence does not suggest that oral NMN or NR at studied doses poses a cancer risk. If you have active cancer, a history of cancer, or are undergoing chemotherapy (especially with NAMPT-targeting drugs), you should not take NAD+ precursors without talking to your oncologist. This is not a gray area. Supplementing NAD+ while on a drug designed to deplete NAD+ in tumors is working against your own treatment.

A nuance that gets lost in the headlines: cancer cells don't need you to take a supplement to get their NAD+. They upregulate NAMPT on their own. The question is whether adding exogenous NAD+ on top of what the tumor is already producing changes the outcome. In mice with pancreatic cancer, it did (for the worse). In a large human cohort (veterans) taking nicotinamide, the outcome was actually fewer skin cancers. These are different compounds, different cancer types, different species, and different study designs. That's why the answer is "unresolved," not "dangerous" or "safe."

One more data point worth noting: the ONTRAC randomized controlled trial (Chen et al., published in the New England Journal of Medicine) gave 500 mg of nicotinamide twice daily to 386 high-risk patients for 12 months and found a 23% reduction in new non-melanoma skin cancers compared to placebo. This is the strongest human evidence that raising NAD+ through a B3-family compound does not increase cancer risk and may, in this specific context, actually reduce it. But ONTRAC used nicotinamide (NAM) at 1,000 mg/day, not NMN or NR. Whether the same protective effect extends to those compounds is unknown.

NAD+ and Autoimmune Conditions

A less-discussed but real concern. NAD+ plays a role in immune cell activation and inflammatory signaling through CD38. In theory, boosting NAD+ could amplify immune responses in people with autoimmune conditions where the immune system is already overactive.

NutritionFacts.org flagged in April 2025 that "for those suffering from chronic autoimmune diseases, such as rheumatoid arthritis, NAD+ boosting could potentially have a 'profound negative impact.'" They cited mouse studies showing that NAMPT inhibitors (which lower NAD+) ameliorated colitis and arthritis. By the same logic, raising NAD+ could worsen these conditions. No human trial has tested this directly, but the theoretical concern is grounded in real biology.

The mechanism makes intuitive sense if you think about what NAD+ does in immune cells. Sirtuins, which depend on NAD+, regulate inflammatory gene expression. SIRT1 and SIRT6 specifically modulate NF-kB signaling, one of the central pathways in autoimmune inflammation. Whether boosting NAD+ tips that balance toward more or less inflammation probably depends on the specific condition, the specific tissue, and the individual patient. Research hasn't gotten granular enough to answer that yet.

Conditions where extra caution is warranted based on current understanding: rheumatoid arthritis, lupus (SLE), inflammatory bowel disease (Crohn's, ulcerative colitis), multiple sclerosis, and psoriasis. If you have any of these and are interested in NAD+ supplementation, this is a conversation for your specialist, not something to self-prescribe based on a supplement label or a longevity podcast.

Niacin vs NMN vs NR: Side Effect Comparison

People lump all NAD+ precursors together when asking about side effects, but the three most common oral ones have noticeably different profiles.

Niacin (nicotinic acid) is the oldest and cheapest. Its signature side effect is flushing: a warm, red, prickly sensation in the face, neck, and chest that can last 15 to 30 minutes. This is prostaglandin-mediated and occurs in the majority of users at pharmacological doses (above 500 mg). Some people find it unbearable. Extended-release niacin formulations reduce flushing but carry a higher risk of liver toxicity. At very high doses (above 3,000 mg/day), niacin has caused serious liver damage. This is well documented and is why high-dose niacin requires liver enzyme monitoring.

NR (nicotinamide riboside) does not cause flushing. The most common side effect across 20+ trials is mild GI discomfort. No liver enzyme elevations have been attributed to NR at doses up to 2,000 mg/day in published trials. NR is generally regarded as the best-tolerated NAD+ precursor in terms of side-effect profile.

NMN (nicotinamide mononucleotide) also does not cause flushing. Its side-effect profile closely mirrors NR: mild GI issues, occasional nausea, rare headache. The July 2026 meta-analysis confirmed no difference in adverse event rates versus placebo. No liver enzyme changes have been observed at studied doses.

If you've tried niacin and quit because of flushing, NMN and NR do not produce that reaction. That's the most practically useful takeaway from the side-effect comparison.

Drug Interactions

Published data on NAD+ precursor drug interactions is sparse. No large interaction study exists. But several theoretical concerns are worth flagging based on known pharmacology:

Chemotherapy drugs that target NAD+ metabolism (NAMPT inhibitors like FK866) would directly conflict with NAD+ supplementation. One is trying to deplete NAD+; the other is trying to raise it. Don't combine these without explicit oncologist guidance.

Immunosuppressants may interact unpredictably with NAD+ boosting given the role of NAD+ in immune cell signaling. No clinical data exists on this interaction, but the biological plausibility is there.

Blood sugar medications: NMN has shown modest effects on insulin sensitivity in some trials. If you're taking metformin, insulin, or sulfonylureas, adding a high-dose NAD+ precursor could theoretically affect glucose control. Monitor your blood sugar more closely when starting.

Niacin (vitamin B3) at high doses causes flushing and can affect liver enzymes. Stacking niacin with NMN or NR adds multiple compounds feeding into the same NAD+ biosynthesis pathways. While not a "drug interaction" in the traditional sense, doubling up on NAD+ precursors from different categories should be done with awareness.

How Long Do NAD+ Side Effects Last?

"How long do NAD side effects last" is searched about 500 times per month. The answer depends on the delivery method.

Oral NMN or NR side effects (GI discomfort, nausea) typically resolve within hours to days. Most users who experience initial GI upset report that it subsides within the first week of daily use as their body adjusts. Taking NMN with food rather than on an empty stomach often helps. If GI symptoms persist beyond two weeks at the same dose, reducing the dose is a reasonable step before discontinuing entirely.

IV NAD+ side effects (chest tightness, nausea, heat sensation) resolve within 30 minutes to a few hours after the infusion ends. They do not carry over to the next day in the vast majority of reported cases. Some clinics give patients anti-nausea medication before the drip starts to preempt these reactions.

Subcutaneous injection site effects (stinging, redness) last minutes to hours. Rotating injection sites and using buffered formulations reduces both intensity and duration. The stinging seems worse with unbuffered preparations and at higher concentrations.

No published report describes persistent or chronic side effects from any form of NAD+ supplementation in humans. That's reassuring, though again limited by short trial durations.

What We Still Don't Know About NAD+ Safety

Honest articles about supplement safety tend to stop at "current evidence shows it's well tolerated." That's accurate but incomplete. Here is what the evidence does not cover yet.

No trial has lasted longer than 12 weeks. The people who take NMN or NR are taking it daily for years, not 12 weeks. Whether cumulative, long-term exposure to sustained NAD+ elevation produces effects that short-term studies can't detect is an open question. The NADage trial in Norway (NCT06208527), a large RCT of NR for age-related functional decline, is expected to report results in 2027 or later and will be one of the first to provide data beyond the 12-week window.

No trial has enrolled participants over age 80 in large numbers. Most studies recruit adults 40 to 70. The oldest populations, who are the ones with the lowest NAD+ levels and the most to theoretically gain from supplementation, are also the ones most likely to have undiagnosed cancers, compromised liver function, and polypharmacy. Whether NAD+ precursors are equally safe in this group is assumed, not proven.

No trial has studied NAD+ precursors in pregnant or breastfeeding women. The safety profile in these populations is entirely unknown. This isn't unusual for supplements, but it's worth stating clearly for anyone considering NMN or NR during pregnancy.

No trial was designed to measure cancer incidence as a primary or secondary endpoint. The cancer question will remain open until a trial specifically powers itself to detect changes in cancer rates. Given how slowly most cancers develop, this would require thousands of participants followed for years. That trial has not been announced.

No large interaction study has tested NAD+ precursors alongside common medications (statins, metformin, SSRIs, blood thinners). The theoretical interaction list exists, but the clinical data doesn't. If you take multiple medications daily, mentioning NMN or NR to your prescribing doctor is prudent even if you're healthy.

None of these unknowns means NAD+ precursors are unsafe. They mean the safety story is incomplete, and anyone selling you certainty about long-term safety is selling you more than the data supports.

Who Should Avoid NAD+ Supplementation?

Based on current evidence and the precautionary principle, these groups should consult a physician before using any NAD+ product:

• People with active cancer or undergoing cancer treatment
• People with a strong family history of cancer who are concerned about risk
• People with autoimmune conditions (rheumatoid arthritis, lupus, IBD, MS)
• People taking NAMPT-targeting chemotherapy drugs
• Pregnant or breastfeeding women (no safety data exists for these populations)
• Children and adolescents (no pediatric safety data exists)

Everyone else: oral NMN and NR appear safe at studied doses based on the current evidence, but "current evidence" means trials lasting 12 weeks or less. Long-term safety is unknown. If you're going to supplement, stick to doses within the range tested in published trials (250 to 1,000 mg/day for NMN, 300 to 1,000 mg/day for NR) and don't assume that more is better.

Liposomal NAD+ Side Effects

"Liposomal NAD+ side effects" is a separate search cluster because liposomal formulations are marketed as having higher absorption than standard capsules. The idea is that wrapping NAD+ (or its precursor NMN/NR) in a lipid envelope protects it through the digestive tract and delivers more of the active compound to cells.

No published clinical trial has compared the side-effect profile of liposomal NAD+ against non-liposomal forms. The theoretical expectation is that higher absorption could mean more pronounced effects, both positive and negative. In practice, user reports suggest the side-effect profile is similar to standard oral NAD+ precursors: mild GI discomfort is the most common complaint, sometimes with a lipid-y aftertaste that some people find unpleasant.

Brands like Rho NAD+ and Cymbiotika sell liposomal NAD+ formulations. "Rho NAD+ side effects" and "Cymbiotika NAD+ side effects" are individually searched terms. There is no brand-specific clinical safety data for any of these products. What you're buying is a liposomal delivery system applied to a molecule (NAD+ or NMN) whose safety profile at the molecular level is known from the trials discussed above. The liposomal wrapper itself is typically made from phospholipids (sunflower lecithin is common) which are generally recognized as safe, though some people experience GI upset from lipid-based supplements in general.

A Note on "Detox" Side Effects

Some wellness sites and clinic marketing materials describe initial NAD+ side effects as "detox reactions" or a "healing crisis." The claim is that feeling worse at first is a sign the NAD+ is "working" and flushing toxins from your system.

This framing has no basis in published clinical research. The mild GI discomfort and nausea reported in trials are standard pharmacological side effects of introducing a bioactive compound, not evidence of detoxification. "Detox" is not a mechanism recognized in the NAD+ biochemistry literature. If you experience side effects, they're side effects. Framing them as therapeutic signals is marketing, not pharmacology.

If side effects are mild and resolve within the first week, continuing at the same dose is reasonable. If they're moderate or worsening, reduce the dose or stop. There is no evidence that pushing through uncomfortable side effects produces better outcomes.

Frequently Asked Questions

Is NAD+ safe to take?

Oral NAD+ precursors (NMN, NR) have been well tolerated in over 30 human trials with no serious adverse events attributed. Short-term use at studied doses appears safe for healthy adults. Long-term data beyond 12 weeks does not exist. People with active cancer, autoimmune conditions, or on specific medications should consult a doctor first.

Can NAD be harmful?

At studied oral doses, NAD+ precursors have not been shown to be harmful in healthy adults. The theoretical concern is cancer: tumors rely on NAD+ for fuel, and boosting NAD+ could theoretically benefit a tumor you don't know you have. No human trial has shown this, but no trial was designed to test for it either.

What are the side effects of NAD injections?

Subcutaneous NAD+ injections commonly cause stinging or burning at the injection site, with occasional brief nausea. IV NAD+ infusions commonly cause chest tightness, nausea, headache, and a heat sensation, all of which are dose-rate dependent and resolve after the session. No formal RCT safety data exists for either injectable route.

What are the side effects of NAD supplements?

Oral NMN and NR: mild GI discomfort (diarrhea, abdominal pain), occasional nausea and headache, rare skin flushing or mouth ulcers. Niacin (another B3 form) causes flushing more frequently. All reported side effects have been mild to moderate and transient.

Does NAD+ cause cancer?

No human trial has shown that NAD+ precursors cause cancer. However, tumors overexpress NAMPT (the enzyme that builds NAD+) and rely on NAD+ for growth. In one mouse study, NMN accelerated pancreatic cancer progression. Nicotinamide (a related B3 compound) reduced non-melanoma skin cancers in the ONTRAC trial. The overall picture is unresolved. People with active cancer should not supplement NAD+ without oncologist guidance.

How long do NAD side effects last?

Oral: hours to days (GI discomfort typically resolves within the first week). IV: 30 minutes to a few hours after infusion ends. Injection: minutes to hours for site reactions. No chronic or persistent side effects have been reported in published literature.

Are NAD patches safe?

No clinical trial has tested NAD+ patches. Whether meaningful amounts of NAD+ cross the skin barrier is itself unproven. Reported side effects are limited to skin irritation from the adhesive.

What are NAD+ nasal spray side effects?

Nasal irritation, burning, and headache have been reported anecdotally. No published clinical trial has evaluated NAD+ nasal spray safety or efficacy. This delivery method lacks formal evidence.

Related Reading

• NAD+ Dosage: Oral, Injection & IV Dosing Guide
• NAD+ Patches: Do They Work?
• NAD+ Nasal Spray: Does It Work?
• What Is NAD+? Benefits, Function & Why It Declines With Age
• Is NAD+ a Peptide? No. Here's What It Actually Is
• NAD+ IV Therapy: How It Works, Costs & Evidence
• NAD+ Injections: Benefits, Side Effects & Cost
• NAD+ Supplements: Types, Evidence & How to Choose
• Best NAD+ Supplements in 2026
• NMN Side Effects: What Clinical Trials Report
• Best NMN Supplements in 2026

References

1. Safety and metabolism-related outcomes of oral nicotinamide mononucleotide supplementation in adults: a systematic review and meta-analysis. Nutrients. 2026;18(14). Published July 2026. View source (PubMed)
2. Zhang J, Poon ETC, Wong SHS. Efficacy of oral nicotinamide mononucleotide supplementation on glucose and lipid metabolism for adults: a systematic review with meta-analysis. Critical Reviews in Food Science and Nutrition. 2025;65(22):4382–4400. doi:10.1080/10408398.2024.2387324 View source (PubMed)
3. de Mello Gindri I, Ferrari G, Pinto LPS, et al. Evaluation of safety and effectiveness of NAD in different clinical conditions: a systematic review. American Journal of Physiology-Endocrinology and Metabolism. 2024;326(4):E417–E427. doi:10.1152/ajpendo.00242.2023 View source (PubMed)
4. Gallagher C, Emmanuel OO. NAD+ supplementation for anti-aging and wellness: a PRISMA-guided systematic review of preclinical and clinical evidence. Ageing Research Reviews. 2026;116:103057. doi:10.1016/j.arr.2026.103057 View source (PubMed)
5. Berven H, Svensen M, Eikeland H, et al. The NAD-brain pharmacokinetic study of NAD augmentation in blood and brain using oral precursor supplementation. iScience. 2026;29(3):114764. doi:10.1016/j.isci.2026.114764 View source (PubMed)
6. Camacho-Pereira J, Tarragó MG, Chini CCS, et al. CD38 dictates age-related NAD decline and mitochondrial dysfunction through an SIRT3-dependent mechanism. Cell Metabolism. 2016;23(6):1127–1139. doi:10.1016/j.cmet.2016.05.006 View source (PubMed)
7. Christen S, Redeuil K, Goulet L, et al. The differential impact of three different NAD+ boosters on circulatory NAD and microbial metabolism in humans. Nature Metabolism. 2026;8:62–73. doi:10.1038/s42255-025-01421-8 View source (PubMed)
8. Nkrumah-Elie Y, Kwon J, Simpson S, et al. Preliminary safety analysis of two pilot clinical trials involving injections of Niagen, nicotinamide riboside chloride. medRxiv (preprint). 2026. doi:10.64898/2026.04.28.26352007 View source (medRxiv preprint)

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.