What NAD+ is
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme in every cell. More than 400 enzymes need it, more than for any other vitamin-derived coenzyme, largely to turn food into energy. Your body makes it from niacin (vitamin B3) and from the amino acid tryptophan.
NAD+ levels may be about 10% to 80% lower in older adults, though the drop isn't seen in every tissue. That decline is why NAD+ is marketed for aging. Whether raising it back helps people live or feel better is still an open question.
NAD+ supplements compared
| Form | What it is | What to know |
|---|---|---|
| Nicotinic acid (niacin) | A form of vitamin B3 | Can cause flushing at 30 to 50 mg or more; high doses over time can harm the liver |
| Nicotinamide (niacinamide) | Another form of vitamin B3 | No flushing; nausea and signs of liver toxicity reported at about 3,000 mg a day |
| Nicotinamide riboside (NR) | A niacin-like precursor | Most studied of the newer precursors; small trials |
| Nicotinamide mononucleotide (NMN) | A niacin-like precursor, close to NAD+ in structure | Small trials up to 24 weeks; see NMN vs NAD+ |
What human trials show
- NAD+ levels: NR and NMN usually raise NAD+ or related compounds in blood and some tissues, though not in every study.
- NR outcomes: trials are mostly 40 people or fewer and last 1 to 20 weeks. Some found modest changes in blood pressure, arterial stiffness or inflammation markers in subgroups. Several randomized trials found no effect on insulin sensitivity, energy use or exercise capacity.
- NMN outcomes: trials of about 14 to 108 people lasting 2 to 24 weeks. A few reported better muscle insulin sensitivity or exercise performance; many found no effect on heart, metabolic, cognitive or sleep measures.
- Niacin: prescription-strength nicotinic acid improves blood lipids, but in large trials adding it to a statin did not lower heart attacks or strokes. Those doses need a clinician's supervision.
Evidence strength: early and mixed. The trials are small, short and use different doses, so no one knows yet who, if anyone, benefits.
Side effects and who should be careful
- NR and NMN have been safe and well tolerated in short trials. Long-term safety is not known.
- In one trial, a high dose of NR combined with pterostilbene raised total and LDL cholesterol.
- Nicotinic acid causes flushing, and long-term high doses, especially extended-release forms, can cause liver injury.
- Pregnancy, breastfeeding, liver disease, kidney disease, or cancer treatment: ask your clinician before taking any NAD+ supplement.
- FDA does not approve dietary supplements before they are sold, so quality and amounts vary by brand.
Stop and call a clinician if you notice unusual tiredness, nausea, loss of appetite, belly pain, or yellowing of your skin or eyes while taking niacin or another NAD+ supplement.
NAD+ IV drips and what to ask
Some clinics offer NAD+ by IV. The trials above studied oral supplements, so their results don't tell you what an IV does. If you're considering one, ask what human evidence supports it, who supervises the infusion, and what it costs over a full course. See IV therapy near me.
If you take medicines or have a chronic condition, Gabriel can check a supplement against your list for free. Bring the exact product and amount to your clinician.
Common questions
Do NAD+ supplements work?
They raise NAD+ related markers, but small human trials show little consistent health benefit so far. A 2023 review called the clinical evidence unclear.
What is the best NAD+ supplement?
No form has been proven better for health outcomes. NR has the most human trials of the newer precursors; NMN has fewer. Niacin is also an NAD+ precursor but causes flushing at higher amounts.
Are NAD+ supplements safe?
NR and NMN have been well tolerated in trials lasting up to about 24 weeks. Long-term safety is unknown, and high-dose niacin can harm the liver.
Do NAD+ levels drop with age?
Studies suggest NAD+ may be about 10% to 80% lower in older adults, though not in every tissue. Whether raising it helps healthy aging isn't proven.
Is NAD+ IV better than pills?
There isn't good evidence to say. The human trials of NAD+ precursors used oral supplements, not IV infusions.
Sources
- Niacin: Fact Sheet for Health Professionals NIH Office of Dietary Supplements
- Dietary Supplementation With NAD+-Boosting Compounds in Humans: Current Knowledge and Future Directions (Freeberg et al., 2023) The Journals of Gerontology: Series A
- Questions and Answers on Dietary Supplements U.S. Food and Drug Administration
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.