NAD+ can be raised, and the levers that move it have been measured in people: exercise multiplies the enzyme muscle uses to build it, sleeping on a regular schedule keeps that machinery in sync, and diet supplies the niacin the body needs to make it each day. What diet cannot do is scale. Milk, the food with the highest known nicotinamide riboside content, carries around one milligram per litre, and the amounts that raise blood NAD+ in trials — 51% with 300 mg a day — are roughly three hundred times larger. This article walks through every lever with its figures: how far it moves the needle, where its ceiling sits and what to do when the target lies above that ceiling.
The starting point: NAD+ falls with age, and it has been measured in people
NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every cell: without it, the enzymes that turn nutrients into energy and those involved in DNA repair cannot work. Its decline with age is not an extrapolation from mice. It has been measured in the skin of 49 people, from newborns to the age of 77 — the older the person, the less NAD+ — and inside the brains of healthy adults using magnetic resonance, where NAD+ drops over the years while its reduced form rises. The underlying question — what this molecule actually does inside the cell — is covered in what NAD+ is and how it works inside the cell.
Before running through the levers it is worth fixing one idea, because it orders everything else. The cell does not wait for NAD+ to arrive from outside: it builds it and recycles it without stopping. Every time a molecule of NAD+ is spent, an offcut is left behind — nicotinamide — which an enzyme called NAMPT turns back into raw material. That recycling loop, the so-called salvage pathway, is the factory. Raising NAD+ means acting on one of two things: the factory or the raw material. Exercise and sleep work on the first. Food and precursors work on the second. And they are not the same size.
Exercise: the lever that enlarges the factory
Two people of the same age can carry very different machinery. In muscle biopsies, athletes show roughly twice the NAMPT — the enzyme that sets the speed limit of the whole recycling loop — of sedentary people, whatever those people weigh. And it does not take a lifetime of training to move that figure: in the same study, three weeks of exercise were enough to raise muscle NAMPT by 127% in sedentary people without obesity.
Age pulls in the opposite direction, and training answers there too. Work from the University of Copenhagen measured salvage-pathway capacity in the muscle of younger and older people: with the years, that capacity falls; with sustained aerobic and resistance exercise, the gap between trained older muscle and young muscle closes. The study's own title says it without hedging: training reverses the age-dependent decline in NAD+ salvage capacity.
These figures are worth reading closely, because they measure something specific: the enzyme and the recycling capacity inside trained muscle, not NAD+ circulating in the blood. And the distinction is no technicality: when blood NAD+ was measured in older adults after three months of supervised training, the figure held steady. Exercise does not fill that tank; it enlarges the factory in the tissue that burns the most energy. That lever does not come in a capsule, and no precursor stands in for it — they act on different parts: one enlarges the machinery, the other gives it more material to process.
Sleep: the factory runs on a clock
Three in the morning on the third night shift of the week, or the flight that leaves the body seven hours off the clock back home. NAD+ synthesis feels that disruption, and the mechanism has been known in detail since 2009, when two teams published it at the same time in Science: the circadian clock — the system that tunes physiology to the day-and-night cycle — directly controls the NAMPT gene. The consequence is that cellular NAD+ is no still pond: it swings across the day, with scheduled peaks and troughs, and in turn sets the activity of the sirtuins, the enzymes that depend on it.
Out of that comes a lever that needs no prescription: regular hours. Sleeping a full night, and sleeping it at the same time each night, keeps the switch that turns production on and off in sync. There is no percentage to offer here — nobody has quantified in humans how much NAD+ a week of rotating shifts costs — but the molecular circuit has been mapped in detail, and it is one of the few levers that depends on buying nothing at all.
Food: real precursors, real amounts
The most repeated question is which foods contain NAD+, and the answer starts with a point of digestive mechanics: NAD+ taken whole does not arrive whole. It has been known since 1983: in the intestine, the molecule is taken apart into its pieces before it passes into the blood. No food — and no product that boasts of “direct” NAD+ — hands the assembled coenzyme to the cells; what arrives are the pieces, and from the pieces the cell builds.
What the diet really supplies is those pieces. The main one is niacin — vitamin B3 — present in meat, fish, peanuts and wholegrain cereals: at around 16 mg a day, the classic manufacturing route has its raw material covered. And there is a second piece, more interesting and far scarcer: milk itself contains nicotinamide riboside, the precursor that headlines the modern trials. It was quantified in 2016 by mass spectrometry: cow's milk carries about 12 micromoles per litre of NAD+ precursor vitamins, 40% of which is NR. Weighed out: around one milligram of NR per litre of milk.
That figure is what sets the scale. Diet keeps the system supplied, and a diet that covers its niacin does exactly what it has to do. But when the aim is to lift NAD+ above the starting level, the numbers from food fall short: the amounts of NR that move blood NAD+ in trials start at 300 mg a day — the equivalent of roughly 250 litres of milk a day. It is not that food “does not work”: it is that food operates in a different order of magnitude. Maintaining is not the same as raising.
Where the scale changes: precursors at trial doses
The same molecule that milk carries by the milligram has been given by the hundreds of milligrams in clinical trials, and there the figures change in kind. The most complete dose-ranging study brought together 140 adults, double-blind and placebo-controlled, and tested three daily amounts of NR over eight weeks: with 100 mg, blood NAD+ rose 22%; with 300 mg, 51%; with 1,000 mg, 142%. The rise showed up as early as two weeks and held for the rest of the study.
It is not an isolated result. In adults aged 55 to 79, a thousand milligrams a day raised NAD+ in blood cells by around 60% in six weeks. In twelve men aged 70 to 80, NR increased the whole set of NAD+ metabolites inside ageing muscle itself, and several of the cytokines linked to inflammation fell in blood. And the pharmacokinetics have been described since 2017: single dose, oral absorption, blood NAD+ up. The rise in NAD+ with NR is documented in independent trials with double-blind design and a placebo group, and the results point in the same direction.
Anyone who has browsed the shelves knows NR is not the only acronym: there is NMN, common in the United States and Asia; there is NADH, the reduced form of the coenzyme itself, with a track record of its own; and there are products that print “NAD+” in big letters. The full comparison between the four forms — what each one has measured in humans, and why the largest head-to-head comparison found no difference between NMN and NR in the NAD+ rise — has an article of its own: NMN or NR, what sets them apart. For anyone shopping in Europe the practical question is settled before the biochemistry gets a word in: NR is the only one of those forms whose European authorisation is complete — cleared as a novel food — with a daily amount defined for supplements, 300 mg a day for an adult. That is no technicality: it means its safety passed a full assessment that the other forms have yet to complete, and that the amount printed on the label has an official ceiling instead of depending on each manufacturer's judgement.
The part diet cannot scale, in one specific capsule
PLENIAGE NR 300 mg is built on exactly those two numbers: one capsule a day with 300 mg of nicotinamide riboside chloride — the middle dose of the 140-adult trial, the one that raised NAD+ by 51%, and at the same time the maximum amount the European authorisation defines. Inside the capsule there are two ingredients: NR and an acacia fibre (Fibregum) as the only excipient. No magnesium stearate, no silicon dioxide, vegetable capsule, made in Spain. When a product is single-ingredient, the whole label reads in five seconds, and that too is a formulation decision.
There is one figure on that label that deserves to come off the back of the pack, because it describes what the product does every day. The 300 mg of NR supply 124 mg of niacin equivalents: 775% of the vitamin's Nutrient Reference Value. And niacin has recognised functions that can be stated in full: it contributes to normal energy-yielding metabolism — the conversion of food into usable energy — and contributes to the reduction of tiredness and fatigue. The same capsule that delivers the precursor at trial dose covers, several times over, the vitamin whose recognised function is precisely energy metabolism; both come from the same place, because NR is, chemically, a form of vitamin B3.
Within the same family there is a second route, built on a different premise. PRO NAD+ NR Advanced Edition combines 100 mg of nicotinamide riboside a day with a block of polyphenols at high doses: resveratrol 294 mg, berberine 145.5 mg and quercetin 142.5 mg, plus hyaluronic acid 72 mg, vitamin C 77.6 mg and piperine 4.75 mg, a compound with published research on its role in the absorption of the polyphenols that travel with it. The logic of that formula is not to maximise the milligrams of precursor: it is to act on several circuits at once in a single serving. The single-ingredient capsule puts every gram of effort into the precursor, at the highest daily amount Europe authorises; the full formula spreads it across seven actives with complementary mechanisms. Two different strategies for the same goal, not a larger and a smaller version of the same thing. The detailed comparison between the two has its own analysis: NR on its own or in a synergistic formula.
Tolerability: what those same trials say
The safety of NR does not have to be assumed: it sits inside the same studies that measured the NAD+ rise. In the 140-adult trial, eight weeks at doses of up to 1,000 mg a day showed no relevant differences from placebo in the adverse effects recorded; in the trial in adults aged 55 to 79, the conclusion is in the title itself: well tolerated. And there is one detail that anyone familiar with vitamin B3 will appreciate: in those trials, NR did not produce the flushing — the hot, red skin — characteristic of nicotinic acid, the classic form of niacin at high doses. It supplies the vitamin equivalents without its most uncomfortable effect. As with any supplement, anyone who is pregnant, breastfeeding or following active medical treatment should check with their healthcare professional first. That said, the position of NR in Europe is the opposite of that of a molecule under suspicion: its safety has the full European assessment behind it, an official daily amount of 300 mg and years of published trials. That is why it is the form you find on European shelves, and also why it is the one PLENIAGE uses.
How the pieces fit together
With the figures on the table, the map draws itself. Exercise is the big lever on the factory: it doubles the rate-limiting enzyme in the muscle of anyone who trains and reverses the decline in capacity that age brings; nothing stands in for it. Sleeping on schedule keeps that factory on time, because NAD+ synthesis is literally wired to the circadian clock. Diet covers the basic raw material — the daily niacin — and that is where its reach ends: maintaining, not raising. The habits that switch on the cell's energy sensors, such as periods without eating, work on neighbouring circuits — autophagy has a story of its own. And when the aim is to push the level above the starting point, the only tool with dose-response trials in people is the precursor: 300 mg of NR a day, 51% more NAD+ in blood at two weeks, sustained at eight.
The levers do not compete with each other, because they do not touch the same part: training enlarges the machinery, the precursor gives it more material to process. Someone who already trains and sleeps well is not “short” of NR; they have the factory ready to make use of it. The rest of the PLENIAGE cellular strategy is in the Cellular Vitality collection, and the practical question of when in the day to take it — morning, on an empty stomach or with food — is settled in detail in when to take NR.
References
- Massudi H, et al. Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLoS One. 2012. PMID: 22848760.
- Zhu XH, et al. In vivo NAD assay reveals the intracellular NAD contents and redox state in healthy human brain and their age dependences. Proc Natl Acad Sci U S A. 2015. PMID: 25730862.
- Costford SR, et al. Skeletal muscle NAMPT is induced by exercise in humans. Am J Physiol Endocrinol Metab. 2010. PMID: 19887595.
- de Guia RM, et al. Aerobic and resistance exercise training reverses age-dependent decline in NAD+ salvage capacity in human skeletal muscle. Physiol Rep. 2019. PMID: 31207144.
- Ramsey KM, et al. Circadian clock feedback cycle through NAMPT-mediated NAD+ biosynthesis. Science. 2009. PMID: 19299583.
- Nakahata Y, et al. Circadian control of the NAD+ salvage pathway by CLOCK-SIRT1. Science. 2009. PMID: 19286518.
- Trammell SA, et al. Nicotinamide riboside is a major NAD+ precursor vitamin in cow milk. J Nutr. 2016. PMID: 27052539.
- Gross CJ, Henderson LM. Digestion and absorption of NAD by the small intestine of the rat. J Nutr. 1983. PMID: 6218262.
- Nikiforov A, et al. Pathways and subcellular compartmentation of NAD biosynthesis in human cells: from entry of extracellular precursors to mitochondrial NAD generation. J Biol Chem. 2011. PMID: 21504897.
- Trammell SA, et al. Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. Nat Commun. 2016. PMID: 27721479.
- Conze D, et al. Safety and metabolism of long-term administration of NIAGEN (nicotinamide riboside chloride) in a randomized, double-blind, placebo-controlled clinical trial of healthy overweight adults. Sci Rep. 2019. PMID: 31278280.
- Martens CR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018. PMID: 29599478.
- Elhassan YS, et al. Nicotinamide riboside augments the aged human skeletal muscle NAD+ metabolome and induces transcriptomic and anti-inflammatory signatures. Cell Rep. 2019. PMID: 31412242.
- Trętowicz MM, et al. Human whole-blood NAD+ levels do not vary with age or lifestyle interventions. Nat Metab. 2026. PMID: 42135539.
- Airhart SE, et al. An open-label, non-randomized study of the pharmacokinetics of the nutritional supplement nicotinamide riboside (NR) and its effects on blood NAD+ levels in healthy volunteers. PLoS One. 2017. PMID: 29211728.
Frequently asked questions (FAQ)
Can NAD+ be raised naturally?
Yes, and with figures measured in people. Exercise raises NAMPT, the enzyme that caps how fast muscle builds NAD+: 127% after three weeks of training in sedentary people, and athletes carry twice as much as they do. Sleeping to a regular schedule keeps synthesis in sync, since it is controlled by the circadian clock. Diet supplies the niacin the body builds NAD+ from every day. What these levers do not do is lift blood NAD+ above the starting point by a measurable percentage: for that, the only thing with dose-response trials in humans is a precursor such as NR.
Which foods contain NAD+?
None of them delivers it whole and usable: NAD+ is taken apart in the intestine during digestion, so what reaches the blood are its pieces. What food really supplies is precursors: niacin (vitamin B3) in meat, fish, peanuts and wholegrain cereals, and nicotinamide riboside in milk, the food in which it has been measured most thoroughly: around one milligram of NR per litre. For a sense of scale, the NR dose that raises NAD+ by 51% in the trials is 300 mg a day: some 250 litres of milk.
How much does exercise raise NAD+?
What has been measured is the machinery, not the level in blood: three weeks of training raised muscle NAMPT by 127% in sedentary people, and aerobic and resistance training reverses the decline in NAD+ recycling capacity that comes with age. In blood, by contrast, the level barely moves: in older adults, three months of supervised training left it unchanged. What exercise enlarges is the factory inside the muscle, which is where most of it is spent.
How much NR does it take to raise NAD+?
The most complete dose-ranging trial, with 140 adults and eight weeks double-blind, measured three daily amounts: 100 mg raised blood NAD+ by 22%; 300 mg, by 51%; 1,000 mg, by 142%. The effect appeared at two weeks and held throughout the study. In Europe, the daily amount defined for an NR supplement is 300 mg for an adult, which is exactly the middle dose of that trial.
Isn't it better to take NAD+ directly — liposomal, for instance?
Ingested NAD+ does not arrive whole: it is taken apart in the intestine into its components before it is absorbed, something described since 1983. That is why the route that has accumulated the trials in people is the precursor, which is well absorbed when taken orally and from which the cell builds its own NAD+. The full comparison between direct NAD+, NR, NMN and NMNH is set out in the article on the differences between NMN and NR.
Does NR replace exercise or sleep?
No, and they work through different routes that do not overlap: exercise and sleep act on the machinery that builds and recycles NAD+ — enlarging it and keeping it on time — while NR supplies the raw material that machinery works on. Someone who trains and sleeps on schedule has the factory ready; the precursor adds substrate — it takes nothing away from the effort. They add up, they do not replace each other.