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NAD+ supplement: what raises NAD+ and does it help?

By the Life in Good Form editors. Updated 2026-10-15.

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What NAD+ supplements contain

NAD+ is nicotinamide adenine dinucleotide. Supplements sold as NAD+ boosters usually contain precursors the body converts to NAD+:

The human trials described below tested NR and other precursors, not direct NAD+ capsules.

Do NAD+ precursors raise NAD+?

Yes, at least in blood:

• Long-COVID trial. In a 24-week double-blind trial of 58 people at a Boston center, 2,000 mg of NR a day raised NAD+ 2.6- to 3.1-fold after 5 to 10 weeks, and levels stayed high at 20 weeks.
• Parkinson's safety trial. In NR-SAFE, 20 people with Parkinson's disease took 1,500 mg of NR twice daily or placebo for four weeks. NR raised blood NAD+ up to 5-fold.

Does higher NAD+ help?

• Cognition and fatigue. In the long-COVID trial, NR did not significantly improve cognition, fatigue, sleep, anxiety or depression compared with placebo. Exploratory within-group analyses suggested some changes after 10 weeks, and the authors called for larger trials. The study was partly funded by an NR maker, and dropout was high in the NR group.
• Muscle in older adults. A 2025 meta-analysis concluded current evidence does not support NR or NMN for preserving muscle mass and function in adults over 60. NR was linked to longer walking distance in peripheral artery disease.
• Parkinson's. NR-SAFE saw improved symptom scores, but the change was also linked to timing of the last levodopa dose. It was a safety trial, not proof of benefit.
• Metabolism. A 2024 meta-analysis of 45 studies with 9,256 participants found NAD+ precursors raised fasting glucose by about 2.17 mg/dL and HbA1c by about 0.11 on average, while lowering CRP, a marker of inflammation.

A closer look at the two NR trials

Long-COVID. Participants were randomized 2 to 1: 37 took NR for 20 weeks, and 21 took placebo for 10 weeks before switching to NR. While on placebo, NAD+ stayed near baseline, then rose 2.6-fold and 2.1-fold after 5 and 10 weeks of NR. Dropout was much higher in the NR-first group (32.4% at 10 weeks and 51.4% at 20 weeks) than in the placebo-first group (14.3%). One serious adverse event was judged unrelated to NR.

Parkinson's. NR-SAFE was run in Bergen, Norway. All 20 participants completed it, and the methyl donor pool stayed intact despite the small homocysteine rise. The authors said the results support testing NR at 3,000 mg a day in larger phase II trials, with safety monitoring.

Safety

• Short-term tolerability. NR-SAFE found 3,000 mg a day for four weeks well tolerated, with no moderate or severe adverse events. NR users had a slight initial rise in homocysteine.
• Blood sugar. Because the 2024 meta-analysis found small increases in glucose and HbA1c, people with diabetes or prediabetes should talk with their doctor first.
• Liver. A 2026 NMN meta-analysis found no rise in the liver enzymes ALT and AST with NMN.
• Long-term safety. Most trials lasted weeks to months.
• Blends. Resveratrol and niacin in combination products have their own cautions.

How to choose an NAD+ supplement

• Know the ingredient. Labels may list NR, NMN, NAD+ or a blend. The trials below used NR to raise NAD+.
• Amount per serving. The NR trials here used 2,000 mg to 3,000 mg a day; follow your label and your doctor.
• Skip big promises. No trial here showed anti-aging, energy or brain benefits beyond placebo.
• Check blood sugar if you have diabetes, given the meta-analysis findings.
• IV NAD+ drips are a separate, clinic-based product not covered by these trials.

What to look for when you buy

Questions people ask

What is an NAD supplement?

Usually a precursor like NR or NMN that the body turns into NAD+. Some products contain NAD+ itself.

Do NAD+ supplements work?

They raise blood NAD+, but trials have not shown clear benefits for cognition, fatigue, muscle or metabolism.

Is NR or NMN better?

The NR trials here showed large rises in blood NAD+. Neither preserved muscle in older adults in a 2025 meta-analysis.

Are NAD+ supplements safe?

Short-term trials found them well tolerated, but a meta-analysis found small rises in blood sugar and HbA1c.

Can diabetics take NAD+ supplements?

Ask your doctor first. NAD+ precursors slightly raised glucose and HbA1c in a 2024 meta-analysis.

Sources

• Effects of nicotinamide riboside on NAD+ levels, cognition, and symptom recovery in long-COVID: a randomized controlled trial (pmc.ncbi.nlm.nih.gov), eClinicalMedicine (PMC12675013)
• NR-SAFE: a randomized, double-blind safety trial of high dose nicotinamide riboside in Parkinson's disease (pmc.ncbi.nlm.nih.gov), Nature Communications (PMC10684646)
• Changes in glucose metabolism, C-reactive protein, and liver enzymes following intake of NAD+ precursor supplementation: a systematic review and meta-regression analysis (pmc.ncbi.nlm.nih.gov), Nutrition and Metabolism (PMC11195006)
• The Effect of Nicotinamide Mononucleotide and Riboside on Skeletal Muscle Mass and Function: A Systematic Review and Meta-Analysis (pmc.ncbi.nlm.nih.gov), Journal of Cachexia, Sarcopenia and Muscle (PMC12022230)
• Safety and Metabolism-Related Outcomes of Oral Nicotinamide Mononucleotide Supplementation in Adults: A Systematic Review and Meta-Analysis (pmc.ncbi.nlm.nih.gov), Nutrients (PMC13414721)

Sources checked 2026-10-15.