NAD+ levels drop significantly as you age, with declines of 30% or more in major organs by your 60s and an estimated 50% reduction in skin over the course of adult aging. The good news: several strategies, from targeted supplements to exercise and dietary changes, can meaningfully restore those levels. Here’s what the evidence supports.
Why NAD+ Declines With Age
NAD+ is a molecule every cell in your body uses to convert food into energy, repair DNA, and regulate hundreds of metabolic processes. Your body constantly breaks it down and rebuilds it through a recycling system called the salvage pathway. The key enzyme in this recycling process, NAMPT, slows down as you get older, which means your body can’t replenish NAD+ as fast as it’s being consumed.
The decline is measurable across multiple tissues. Brain NAD+ drops 10% to 25% between young adulthood and old age, based on MRI studies. Liver samples from people over 60 show roughly 30% lower NAD+ compared to those under 45. Even cerebrospinal fluid shows about a 14% decrease after age 45. This isn’t a sudden crash but a steady erosion that accelerates the cellular wear and tear associated with aging.
NR and NMN Supplements
The two most studied NAD+ precursor supplements are nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). Both feed directly into the salvage pathway, giving your body raw material to build more NAD+. They work through slightly different entry points but arrive at the same destination.
NR has the longer track record in human trials. A dose of 1,000 mg twice daily (2,000 mg total) increased whole-blood NAD+ levels up to 2.7-fold after a single dose in healthy volunteers. An 8-week trial testing doses up to 1,000 mg per day in overweight and healthy adults confirmed that NR is safe and well-absorbed orally. Most commercial products are sold in the 300 to 1,000 mg per day range.
NMN research in humans is newer but growing. A study published in Scientific Reports tested 1,250 mg of NMN taken once daily for four weeks in healthy adults and found no serious adverse events and no concerning changes in kidney function, blood work, or body composition. Separate trials have shown practical benefits: a 25% improvement in insulin sensitivity in people with prediabetes and type 2 diabetes, and dose-dependent improvements in aerobic exercise capacity in amateur runners taking 300 to 1,200 mg per day for six weeks.
Both supplements are generally well tolerated at the doses studied so far. The main difference for most people comes down to price and availability, since NMN has faced more regulatory uncertainty in some markets.
Exercise Directly Rebuilds NAD+ Capacity
Exercise doesn’t just consume energy. It actually upregulates the enzyme your body uses to recycle NAD+. A 12-week study measuring NAMPT levels in skeletal muscle found that both aerobic and resistance training produced significant increases, and the effect was even more pronounced in older adults.
Aerobic training boosted NAMPT by about 12% in young people (35 and under) and 28% in older adults (55 and over). Resistance training was equally effective, raising NAMPT roughly 25% in the young group and 30% in the older group. This means exercise partially reverses the age-related decline in your body’s ability to make its own NAD+. Notably, other enzymes in the pathway didn’t change with training, so the benefit is specifically tied to this rate-limiting recycling step.
The practical takeaway: both cardio and weight training work. You don’t need to pick one. The study used a standard 12-week program, suggesting that consistent training over a few months is enough to see measurable changes in NAD+ salvage capacity.
Fasting and Caloric Restriction
When your body senses a calorie deficit, it shifts into a metabolic state that naturally raises NAD+ levels. Caloric restriction increases concentrations of metabolic signals like NAD+ and AMP while reducing glucose, insulin, and growth hormone. This combination activates the same salvage pathway that supplements target, upregulating NAMPT to produce more NAD+ from recycled components.
You don’t necessarily need extended fasting to tap into this. Time-restricted eating, where you compress your daily meals into an 8- to 10-hour window, creates enough of a metabolic shift to nudge these pathways. The key trigger is a sustained period without incoming calories, which changes the ratio of energy molecules in your cells and signals that NAD+ recycling needs to ramp up.
Foods That Supply NAD+ Precursors
Your body can build NAD+ from dietary sources, primarily niacin (a B vitamin found in meat, fish, and dairy) and the amino acid tryptophan. About 15 mg per day of niacin is enough to meet basic NAD+ synthesis needs. Rich sources include chicken breast, tuna, turkey, salmon, and fortified grains.
Some foods also contain trace amounts of NMN itself. Broccoli leads the pack at 0.25 to 1.88 mg per 100 grams, followed by avocado and tomato at 0.26 to 1.60 mg per 100 grams. Cucumber, cabbage, and immature soybeans (edamame) contain smaller amounts. Raw beef and shrimp have 0.06 to 0.42 mg per 100 grams, and cow’s milk contains NMN at micromolar concentrations.
To be clear, the NMN in food is orders of magnitude lower than supplement doses. You’d need to eat pounds of broccoli to match a single capsule. But a diet rich in these foods ensures your body has a steady supply of all the building blocks it needs for NAD+ production, and the niacin content of a balanced diet covers the baseline requirement easily.
Reducing NAD+ Breakdown With Flavonoids
Boosting production is only half the equation. Your body also has enzymes that actively consume NAD+, and one of the most aggressive is CD38, which increases with age and inflammation. Slowing CD38 down means more of the NAD+ you produce actually sticks around.
Two plant compounds, apigenin and quercetin, have been shown to inhibit CD38 and raise intracellular NAD+ levels as a result. Research published in the Journal of Biological Chemistry demonstrated that treating cells with apigenin blocked CD38 activity, increased NAD+ concentrations, and activated protective enzymes called sirtuins that depend on NAD+ to function. Quercetin showed similar inhibitory effects.
Apigenin is found in parsley, chamomile tea, celery, and dried oregano. Quercetin is abundant in onions, capers, berries, and apples. Including these foods regularly won’t produce the concentrated doses used in cell studies, but they contribute to an overall strategy of protecting your NAD+ pool from unnecessary depletion. Quercetin supplements, typically dosed at 500 to 1,000 mg per day, are widely available for those who want a more targeted approach.
Sleep and Circadian Rhythm
NAD+ production isn’t constant throughout the day. It follows a circadian rhythm, with NAMPT gene expression peaking at the start of your active period and NAD+ levels oscillating on a 24-hour cycle. This pattern has been clearly documented in liver and fat tissue, where both NAMPT protein and NAD+ concentrations rise and fall in sync with the body’s internal clock.
This means disrupted sleep and irregular schedules can blunt your body’s natural NAD+ production cycle. Shift work, late-night light exposure, and inconsistent meal timing all interfere with the clock machinery that drives NAMPT expression. Keeping a consistent sleep-wake schedule, getting morning light exposure, and eating meals at regular times helps maintain the rhythmic NAD+ production your cells are designed for. It’s one of the simplest and most overlooked factors in the equation.
Putting It All Together
No single intervention works in isolation. The most effective approach combines several strategies that target different parts of the NAD+ cycle. Exercise and fasting boost your body’s recycling enzyme. Supplements provide extra raw material. Flavonoid-rich foods help prevent unnecessary breakdown. And consistent sleep preserves the natural rhythm of production.
If you’re starting from scratch, regular exercise (both cardio and strength training) and a nutrient-dense diet are the foundation. Adding an NR or NMN supplement at studied doses of 300 to 1,000 mg per day is the next logical step if you want more aggressive support. Pair that with consistent sleep habits and foods rich in apigenin and quercetin, and you’re covering both sides of the NAD+ balance sheet: making more and losing less.