NAD+ levels naturally decline with age, dropping roughly 50% in skin tissue over an adult lifetime and about 30% in liver tissue by age 60. The good news: several strategies can meaningfully raise those levels back up, from supplements and diet to exercise, fasting, and sleep habits. Here’s what actually works and how much difference each approach makes.
Why NAD+ Drops With Age
NAD+ is a molecule every cell in your body uses to convert food into energy, repair DNA, and regulate your internal clock. Your body constantly builds it and breaks it down, but the balance shifts as you get older. One major reason is an enzyme called CD38, which chews through NAD+ and becomes more active with age. At the same time, the enzymes that produce NAD+ slow down. Brain imaging studies show a 10% to 25% decline between young adulthood and old age, and the drop in other tissues can be even steeper.
This decline is linked to many hallmarks of aging, from lower energy and slower recovery to increased inflammation. Boosting NAD+ means either increasing production, supplying the raw materials your body needs to make more, or slowing the rate at which it gets broken down. The most effective approach combines several of these strategies.
NMN and NR Supplements
The two most studied NAD+ precursor supplements are nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR). Your body converts both into NAD+ through relatively short metabolic pathways. A head-to-head clinical trial published in Nature Metabolism found that after 14 days of daily supplementation, both NR and NMN roughly doubled whole-blood NAD+ concentrations compared to placebo. The increases were statistically comparable between the two, so neither has a clear edge.
Plain niacin (nicotinamide) did not produce the same sustained boost. It caused a brief spike but no lasting change in baseline NAD+ levels, making NMN and NR the stronger choices for chronic supplementation.
A 60-day clinical trial testing NMN at 300, 600, and 900 mg daily in healthy middle-aged adults found all three doses safe and well tolerated, with no concerning side effects. The 600 mg dose appeared to be the sweet spot, producing the highest blood NAD+ concentrations and the best physical performance results. NR has typically been studied at doses of 250 to 1,000 mg per day with a similar safety profile. As of 2025, the FDA has confirmed that NMN can be legally sold as a dietary supplement in the United States, reversing an earlier exclusion.
Foods That Supply NAD+ Building Blocks
Your body makes NAD+ from four dietary precursors: two forms of niacin (nicotinic acid and nicotinamide), nicotinamide riboside, and the amino acid tryptophan. You don’t need supplements to get these. They’re abundant in common foods.
- Niacin-rich foods: Poultry, tuna, salmon, beef, fortified cereals, legumes, seeds, and nutritional yeast are all excellent sources. Milk, green leafy vegetables, coffee, and tea provide smaller amounts.
- Tryptophan-rich foods: Turkey, chicken, eggs, cheese, nuts, and seeds supply tryptophan, which your body converts to NAD+ through a longer metabolic pathway called the kynurenine pathway. This route is less efficient than the direct niacin pathways, but it still contributes meaningfully to your total NAD+ pool.
A diet consistently rich in these foods ensures your body has the raw materials it needs. No single food will spike your NAD+ levels dramatically on its own, but chronic deficiency in niacin or tryptophan will impair production.
Exercise Stimulates NAD+ Production
Exercise doesn’t just consume energy. It activates the machinery that makes NAD+. Physical activity increases levels of NAMPT, the rate-limiting enzyme in the NAD+ salvage pathway (the main recycling route your body uses to regenerate NAD+ from its breakdown products). Research published in Aging Cell showed that moderate-intensity exercise triggers the release of NAMPT into the bloodstream, packaged inside tiny cellular messengers called extracellular vesicles. These vesicles travel to other tissues and boost NAD+ activity in recipient cells, creating a body-wide effect.
This response was most prominent in younger, fitter individuals, but older adults still benefit. The researchers described this mechanism as a way to limit age-related NAD+ decline through systemic delivery of NAMPT during exercise. Both aerobic and resistance training have been shown to upregulate NAMPT in skeletal muscle. You don’t need extreme training, as moderate-intensity activity is enough to trigger the effect.
Fasting and Calorie Restriction
When your body senses an energy shortage, it ramps up NAD+ production. Fasting and calorie restriction both increase intracellular NAD+ levels, typically by up to twofold. This is the same magnitude of increase seen with genetic interventions and pharmacological approaches in research settings.
The rise in NAD+ during fasting activates a family of proteins called sirtuins, which regulate DNA repair, inflammation, and metabolic efficiency. This is one reason calorie restriction has been consistently linked to longevity in animal studies. Time-restricted eating (a form of intermittent fasting) can produce similar metabolic signaling, though the exact timeline and magnitude depend on the duration and severity of the fast.
Sleep and Your Circadian Clock
NAD+ levels aren’t constant throughout the day. They oscillate on a 24-hour cycle, rising and falling by about 2.5-fold. This rhythm is directly controlled by your circadian clock. The core clock proteins CLOCK and BMAL1 switch on the gene for NAMPT, the same enzyme that exercise activates, at specific times of day. This creates a feedback loop: NAD+ production fuels sirtuin activity, which in turn helps maintain the clock itself.
When this clock is disrupted, such as through shift work, irregular sleep schedules, or chronic sleep deprivation, the rhythmic expression of NAMPT breaks down. Studies in clock-mutant mice show that NAD+ oscillation is completely abolished when the circadian machinery is broken. For practical purposes, this means that maintaining a consistent sleep-wake schedule and getting adequate sleep are foundational to healthy NAD+ cycling. No supplement can fully compensate for a disrupted circadian rhythm.
Reducing NAD+ Breakdown With Flavonoids
Boosting NAD+ isn’t only about making more of it. Slowing its destruction matters too. The enzyme CD38 is the primary NAD+-degrading enzyme in mammals, and its activity increases with age and inflammation. Two plant compounds, apigenin and quercetin, have been shown to inhibit CD38 both in isolated cells and in purified enzyme experiments.
Apigenin blocked CD38 activity at relatively low concentrations, and the inhibition observed in living cells closely matched what was seen in lab assays. When CD38 was inhibited, intracellular NAD+ levels rose and sirtuin activity increased as a result. Quercetin showed a very similar inhibition profile. Apigenin is found in parsley, chamomile tea, celery, and citrus fruits. Quercetin is abundant in onions, apples, berries, and capers. Including these foods regularly may help preserve the NAD+ your body produces, though human clinical data on this specific mechanism is still limited.
IV NAD+ Drips vs. Oral Supplements
Clinics offering intravenous NAD+ infusions have become increasingly popular, and there is a real pharmacological basis for the approach. Oral NAD+ itself does not effectively raise plasma or tissue NAD+ levels because it gets broken down in the gut before reaching your bloodstream. IV infusion bypasses this problem entirely and is currently the only clinically recognized method to deliver NAD+ directly into circulation.
However, this comparison is somewhat misleading. Oral NMN and NR are not the same as oral NAD+. They are precursors that survive digestion and are converted into NAD+ inside your cells, which is why they successfully double blood NAD+ levels in clinical trials. IV NAD+ infusions are expensive (often $250 to $1,000 per session), time-consuming, and need to be repeated regularly. For most people, oral precursors at 300 to 600 mg daily offer a more practical and well-studied path to sustained NAD+ elevation.
Combining Strategies for the Biggest Effect
Each of these approaches works through a different mechanism, which means they can stack. Exercise and fasting increase the activity of NAMPT, your body’s main NAD+ recycling enzyme. NMN and NR supply additional raw material for that enzyme to work with. Flavonoid-rich foods slow the breakdown of the NAD+ you produce. And consistent sleep keeps the whole system oscillating in rhythm.
A reasonable combined approach looks like regular moderate exercise, a diet rich in niacin, tryptophan, and flavonoids, some form of caloric restriction or time-restricted eating, consistent sleep timing, and an NMN or NR supplement at around 300 to 600 mg daily if you want the extra boost. No single intervention is a magic bullet, but together they address both sides of the equation: production and preservation.