NAD+: A molecule that declines with age - what the science shows – QED

When you're thirty, partying until morning costs you one sleepy day. Ten years later, the same night requires two days to recover. Something inside has definitely changed. That something has a short name, constantly repeated in the longevity world: NAD+.

Much is said about NAD+, loudly and beautifully. Let's see what scientists have actually measured – not what advertisements say, but studies conducted with humans.

What is NAD+ and what does it do in the body?

NAD+ (nicotinamide adenine dinucleotide) is a molecule found in every cell of your body. Without it, cells simply couldn't produce energy.

Two main functions of NAD+:

Energy. NAD+ participates in normal energy metabolism and helps convert food into the fuel that cells can actually use. This process occurs in mitochondria, the cell's powerhouses, and without NAD+, mitochondria would simply stop.
Cell maintenance. NAD+ is essential for several enzyme groups: sirtuins and PARP proteins. These cellular machines oversee DNA and regulate cell behavior. They are like a team of housekeepers for whom NAD+ is a working tool (Covarrubias, 2021).

In short: NAD+ is simultaneously part of the fuel chain and a tool for cell maintenance. This is why this molecule has become so interesting and important to science.

Does NAD+ really decrease with age?

You can't just ask a cell how much NAD+ it contains. It needs to be measured somehow. Scientists have done this measurement by looking through several different "windows" into body processes.

Skin. The earliest human tissue data (Massudi, 2012). Skin samples from people aged from newborns to 77 years were studied. NAD+ levels decreased with age – in both men and women.

Brain. Brain biopsies cannot be taken, so magnetic resonance spectroscopy was used to measure NAD+ in living, functioning brains without any invasive procedures. Lower NAD+ levels were found in the brains of older people (Zhu, 2015).

Muscles. Muscle samples from young and older people were compared (Janssens, 2022). NAD+ was among the substances that decreased the most with age. The most interesting detail: in physically active older people, its level was closer to that of young people. NAD+ levels also correlated with the number of steps walked per day.

For fairness: NAD+ levels in the body do not decrease uniformly with age. In some tissues, the decline is clear and measurable, in others – almost imperceptible. And NAD+ levels in the blood remain relatively stable regardless of age, so a typical NAD+ blood test does not necessarily show the situation in the tissues themselves. "NAD+ decreases with age" is true, but with an asterisk – it depends on which part of the body you look at.

Why precursors, not just NAD+

A logical question: if NAD+ is deficient, why not simply take a few handfuls?

The problem is that the NAD+ molecule itself is too large to easily enter cells. Therefore, the body has a cleverer way – it produces NAD+ itself from smaller building blocks belonging to the vitamin B3 family. Two of these are what everyone talks about: NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide).

So precursors act not as a direct infusion of NAD+, but as raw material from which the cell itself assembles as much as it needs.

What human studies show

One thing in this field is almost unquestioned: oral NR or NMN supplements reliably increase NAD+ levels in the human body. QED NAD Booster, containing NR, also does this.

NR, blood. In a study with 140 participants (Conze, 2019), 1000 mg of NR per day increased blood NAD+ by as much as 142% in two weeks. This elevated level remained throughout the eight weeks of the study.
NR, muscles. Elhassan (2019) examined muscle tissue itself and found that NR increases NAD+ not only in the blood but also in the tissue – where it is needed.
NMN, older men. 250 mg of NMN per day for 12 weeks increased blood NAD+ and also slightly improved walking speed and hand strength (Igarashi, 2022).
NMN, walking endurance. In a dose-response study with 80 participants (Yi, 2023), all NMN doses increased blood NAD+, and 600 and 900 mg improved the six-minute walk test result and the participants' well-being.

But again – without exaggeration. The fact that precursors increase NAD+ is firmly proven. But the functional benefits (walking, strength, well-being) – although observed in studies, are modest. Overall, there is still not enough data on one specific benefit. Not every measured indicator has changed. So the most accurate way to put it is: NAD+ precursors are promising and well-tolerated, but not a miracle in a bottle.

What to take away from all this

The age-related decline in NAD+ levels in several tissues is not a myth; it has indeed been measured. NR and NMN reliably raise these levels and can contribute to maintaining normal energy metabolism and physical activity. But at the same time, it is not a magical reversal of age, as sometimes presented in marketing materials.

Knowing exactly what the studies showed is the most important thing. Then we choose not based on advertising, but on data.

FAQ

Does NAD+ really decrease with age?

In several tissues – skin, brain, muscles – this has been directly measured. But the decline is not uniform, and blood indicators do not necessarily reflect what is happening in the tissues. In short: yes, with nuances.

NR or NMN – which is better?

Both reliably increase NAD+. NR has more blood and muscle data, NMN – more functional studies (walking, strength, well-being). There is no clear winner yet, but at least for now NMN is not approved in the European Union.

How much precursors should be taken?

In studies, NR showed an effect from 100 mg, NMN from 250 to 900 mg per day. As with any supplement, individual circumstances vary, so always consult a doctor before starting to use it.