Quick answer: NAD+ is a coenzyme found in every cell. It helps turn food into energy in mitochondria and fuels enzymes that repair DNA and regulate metabolism. The body makes NAD+ from tryptophan and forms of vitamin B3 (niacin), and recycles it constantly. Levels tend to decline with age. Exercise, sleep, a nutrient-rich diet and time-restricted eating may support it; supplement research is still early.
Key takeaways
NAD+ is a coenzyme found in every cell that helps turn food into energy and fuels DNA repair enzymes.
The body makes it from tryptophan and forms of vitamin B3 and recycles it through the salvage pathway.
Levels tend to fall with age, and exercise, sleep and time-restricted eating may support them while supplement research is still early.
What is NAD+?
Nicotinamide adenine dinucleotide (NAD+) is a helper molecule that carries electrons in energy production and acts as fuel for repair enzymes.
How your body makes NAD+
From tryptophan
An amino acid in protein foods. This pathway relies on vitamin B6, riboflavin and iron. Chronic inflammation can divert tryptophan away from this route.
From niacin (vitamin B3)
Nicotinic acid and nicotinamide from foods like poultry, fish, meat and legumes are converted to NAD+. Large amounts of nicotinic acid cause flushing.
Recycling (the salvage pathway)
Most NAD+ is recycled from nicotinamide. Precursors studied as supplements include nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN).
Why NAD+ matters for aging
NAD+ sits at the center of several processes that change with age, explained in plain language:
DNA repair
Repair enzymes called PARPs use NAD+ to fix DNA damage. When damage is high, they can use up NAD+.
Mitochondrial energy
Mitochondria need NAD+ to make energy. Lower NAD+ is linked with less efficient mitochondria and more oxidative stress. See mitochondrial health.
Sirtuins and metabolism
Sirtuins are NAD+-dependent proteins that help regulate metabolism, inflammation and stress responses.
Liver clearance
NAD+ supports liver enzymes that process alcohol and other compounds. See how liver clearance works.
Supporting NAD+ naturally
You can support NAD+ naturally with regular exercise, especially aerobic and strength training, consistent, quality sleep, and a diet with enough protein and niacin-rich foods. Time-restricted eating may help some people (see intermittent fasting), and limiting alcohol helps as well.
What about supplements?
NR has been shown to raise NAD+ levels in human studies, and NMN is also being studied, but evidence that either one improves health outcomes in people is still limited, and long-term safety is not established. High-dose niacin can affect the liver and blood sugar. Discuss any supplement with your provider.
Healthy aging lens
NAD+ connects energy, repair and metabolism, which are all central to how we age. Lifestyle remains the best-supported way to support it. See metabolism and longevity.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if your symptoms are ongoing, worsening or affecting daily life, or if you take medications or have a chronic condition and are considering supplements. The same is true if you want a personalized, root-cause plan, or if you are pregnant or breastfeeding.
See a medical provider promptly for chest pain, trouble breathing, severe abdominal pain, high fever, or signs of an allergic reaction.
What the research shows
Human trials of NAD+ precursors are still small and short. In a 2018 crossover trial by Martens and colleagues, healthy middle-aged and older adults took nicotinamide riboside (NR) or a placebo for 6 weeks each, in random order and double-blind. NR was well tolerated and raised NAD+ metabolism in blood cells, and the authors suggested that future trials look more closely at possible effects on blood pressure and arterial stiffness. The abstract does not report the number of participants or the dose, and the study was not designed to show clinical benefits.
Another precursor, nicotinamide mononucleotide (NMN), has been tested on metabolism. In a 2021 double-blind trial by Yoshino and colleagues, postmenopausal women with prediabetes and overweight or obesity took NMN or a placebo for 10 weeks. Muscle insulin sensitivity, measured with a gold-standard clamp test, and muscle insulin signaling improved with NMN but not with placebo. The abstract does not report the number of women or the dose, and results in this specific group may not apply to others. Overall, the human evidence for NAD+ supplements remains early.
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Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Is there any reason for me to consider an NAD+ precursor, or should I focus on habits first?
Is NAD+ support a reasonable choice alongside my current medications and supplements?
Would it be worth checking any labs before I try NAD+ support, or is my history enough to decide?
What would tell us that NAD+ support is working well for me, and how long should we wait before reviewing it?
Frequently asked questions
What is NAD+?
A coenzyme in every cell needed for energy production and DNA repair.
Does NAD+ decline with age?
Research shows levels tend to fall with age.
Do NAD+ supplements work?
They raise NAD+ levels, but health benefits in people aren’t yet proven.
How can I support NAD+ naturally?
Exercise, sleep, a nutrient-rich diet and limiting alcohol.
Sources
- Martens CR, Denman BA, Mazzo MR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun 2018. PMID: 29599478. https://pubmed.ncbi.nlm.nih.gov/29599478/
- Yoshino M, Yoshino J, Kayser BD, et al. Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science 2021. PMID: 33888596. https://pubmed.ncbi.nlm.nih.gov/33888596/
- Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol 2021. PMID: 33353981. https://pmc.ncbi.nlm.nih.gov/articles/PMC7963035/
- Massudi H, et al. Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLoS One 2012. PMID: 22848760. https://pmc.ncbi.nlm.nih.gov/articles/PMC3407129/
- MedlinePlus: Niacin
- MedlinePlus: Healthy Aging
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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