The relationship between NAD+ and ageing is one of the more compelling threads in longevity science. NAD+ is a coenzyme your cells depend on to turn food into energy and to run their repair machinery, and its levels do not hold steady across a lifetime. Research has documented a significant, age-dependent decline in NAD+, with direct measurements in living human tissue confirming the trend (Zhu et al., 2015; Covarrubias et al., 2021). That decline tracks with several of the changes people tend to notice with age: less energy, slower recovery, foggier focus. This post explains what NAD+ actually does, why it falls with age, what the evidence does and does not show, and the realistic options for supporting your levels, including where IV therapy fits in.
What Is NAD+ and Why Does It Matter?
NAD+ stands for nicotinamide adenine dinucleotide, a coenzyme found in every living cell. It does two very different jobs at once.
First, it is the workhorse of energy metabolism. NAD+ ferries electrons between reactions, accepting them to become NADH and handing them back to become NAD+ again, a cycle that helps your mitochondria produce the energy your cells run on (Verdin, 2015).
Second, it is a cosubstrate that other enzymes consume in order to function. These include the sirtuins, a family of enzymes involved in DNA repair and metabolic regulation, as well as PARPs and CD38 (Covarrubias et al., 2021). Through these enzymes, NAD+ has a hand in DNA repair, the regulation of your circadian rhythm, and the day-to-day maintenance that keeps cells in good working order.
A useful way to picture it: NAD+ is part rechargeable courier and part swipe card. As a courier, it shuttles electrons around to keep the energy supply moving. As a swipe card, it grants your cellular repair and maintenance crews access to do their work. Reduced NAD+ availability may influence the activity of several NAD-dependent enzymes involved in DNA maintenance and metabolic regulation.
How NAD+ Levels Change as You Age
NAD+ does not stay at youthful levels. Using a non-invasive imaging technique, researchers have measured an age-dependent decline in NAD+ in the living human brain (Zhu et al., 2015), and a gradual fall in NAD+ has now been documented across multiple tissues and species, including humans (Covarrubias et al., 2021).
Why does it drop? The picture is one of supply and demand moving in the wrong directions at once. On the demand side, consumption rises: the enzyme CD38 increases with age and steadily drains the available NAD+ (Camacho-Pereira et al., 2016). Other NAD-consuming enzymes, including the PARPs that draw on NAD+ during DNA repair, add to the same demand (Covarrubias et al., 2021). On the supply side, the salvage pathway that recycles NAD+ becomes less efficient over time (Covarrubias et al., 2021). The result is a slow net decline. The rate and size of that decline vary by tissue, by how it is measured, and from one person to the next, so any single figure is best read as a general trend rather than a precise rule.
This decline is commonly associated with several things people notice as they get older: persistent fatigue, slower recovery after exertion, brain fog, and disrupted sleep. It is worth being clear that these are general associations drawn from the wider literature on NAD+ biology, not a diagnostic checklist. Many factors influence energy and recovery, and low NAD+ is only one possible thread among them.
If energy and recovery are what you are focused on, our IV therapy range is designed with exactly that in mind, including a dedicated NAD+ drip programme structured as a tiered ladder for different stages of use.
What the Research Says About NAD+ and Ageing
The interest in NAD+ and ageing rests on a few connected lines of evidence.
The first is the sirtuins, enzymes involved in cellular stress responses, DNA maintenance, and metabolic regulation. Crucially, they cannot work without NAD+. As NAD+ becomes limiting with age, sirtuin activity is thought to fall with it, which researchers have proposed as one route by which declining NAD+ contributes to age-associated changes (Imai & Guarente, 2014).
The second is energy. Because NAD+ is central to how mitochondria generate energy, a fall in NAD+ has been linked to the decline in mitochondrial function seen with ageing (Verdin, 2015). There is also a link to cellular senescence and immune ageing: as senescent cells accumulate, NAD+-consuming activity rises, adding to the drain on the available pool (Covarrubias et al., 2021).
It helps to place this in context. The influential Hallmarks of Ageing framework organises the biology of getting older into a set of interconnected processes, a list that has since expanded (López-Otín et al., 2013; López-Otín et al., 2023). NAD+ does not sit in a single box. Instead, it threads through several hallmarks at once, most clearly mitochondrial dysfunction, but also the DNA repair and nutrient-sensing processes that NAD+-dependent enzymes help govern.
A word of honesty about the evidence, because it is the part that gets lost in most marketing. The strongest results come from animal models. In one landmark study, long-term supplementation with an NAD+ precursor mitigated age-associated physiological decline in mice (Mills et al., 2016). Human evidence is earlier-stage. A randomised, placebo-controlled trial in healthy middle-aged and older adults found that an oral precursor was well tolerated and did raise NAD+ levels, but it stopped short of demonstrating the broader anti-ageing outcomes seen in animals (Martens et al., 2018). Early evidence indicates real promise. It does not yet amount to proof that restoring NAD+ slows human ageing.
Can You Restore NAD+ Levels?
The short answer is that you can raise NAD+, and there are several routes to doing so. How well each one works in humans, and for what, is still being worked out.
Oral precursors: NMN and NR
You do not supplement NAD+ directly so much as feed the pathway that makes it. Two precursors, nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), are converted by the body into NAD+ through the salvage pathway (Yoshino, Baur & Imai, 2018). Of the two, NR has the more developed human evidence base: the randomised trial mentioned above found that chronic NR supplementation was well tolerated and effectively raised NAD+ in healthy middle-aged and older adults (Martens et al., 2018).
The caveat is bioavailability. An oral precursor has to survive digestion and first-pass metabolism in the liver before it reaches the rest of the body, which limits how much ultimately becomes available to your tissues. This is part of why some people look to other delivery routes.
IV NAD+ therapy
The rationale for intravenous NAD+ is straightforward: delivering it into the bloodstream bypasses gut absorption and first-pass metabolism, the two steps that blunt an oral dose. In practice, a session involves a slow infusion in a comfortable clinical setting, with the protocol tailored to the individual.
We will be candid here too. The rationale is sound, but the published evidence specifically for IV NAD+ is still limited compared with the oral precursor data. It is an area of active interest rather than settled science, which is exactly why it belongs in a conversation with a physician rather than in a self-prescribed plan.
At WellNest we offer three options on a structured NAD+ ladder. The NAD+ Starter is designed for first-time users looking to initiate cellular repair safely and comfortably. The NAD+ Standard is the core clinical-grade dose for sustained maintenance and performance. The NAD+ Advanced is for experienced users seeking maximum cellular restoration under full clinical oversight. Your physician determines the appropriate starting point based on your history and health picture.
Lifestyle levers that help preserve NAD+
Before any drip or capsule, the everyday inputs matter. Exercise, adequate sleep, and good metabolic health are associated with favourable NAD+ metabolism and remain foundational pillars of healthy ageing (Rajman, Chwalek & Sinclair, 2018). The proposed mechanisms are intuitive: regular exercise and time-restricted eating are thought to support the body's own NAD+ production, while moderating alcohol removes a process that competes for the same pool. None of these is glamorous, and all of them are within your control, which makes them a sensible foundation regardless of what else you choose to do.
What We Know, and What We Do Not Yet Know
The honest position sits between hype and dismissal. It helps to separate what the science has established from what it has not.
What we know
NAD+ is essential for cellular energy metabolism and a wide range of enzymatic processes (Verdin, 2015).
NAD+ levels appear to decline with age (Zhu et al., 2015; Covarrubias et al., 2021).
Oral NAD+ precursors such as NR and NMN can raise circulating NAD+ levels (Martens et al., 2018; Yoshino, Baur & Imai, 2018).
NAD-dependent pathways are implicated in several biological processes associated with ageing (Imai & Guarente, 2014; Rajman, Chwalek & Sinclair, 2018).
What we do not yet know
Whether increasing NAD+ slows human ageing.
Whether raising NAD+ levels improves lifespan or healthspan in people.
Which individuals are most likely to benefit.
This is exactly why NAD+ therapy belongs in a conversation with a physician rather than a self-prescribed plan.
Who Considers NAD+ Therapy?
NAD+ therapy tends to appeal to a few groups, none of whom are using it to treat a diagnosed condition:
Individuals interested in healthy ageing and metabolic health sometimes explore NAD+ therapy as part of a broader wellness strategy.
People in their 40s and beyond who have started to notice slower recovery and want to be proactive about it.
Athletes and active people looking to optimise recovery between sessions.
If you want to understand your baseline before committing to a protocol, our NAD Profile blood test measures your current NAD+, NADH, and related metabolites so any decision is grounded in data rather than guesswork.
Whether IV therapy is a sensible fit is an individual question, not a one-size answer. Our physicians assess your baseline and overall health picture before recommending any protocol.