NAD+ — what it is, what it does in the body and where the evidence stops

NAD+ now appears in supplement adverts, in longevity clinics and in articles about ageing. The odd part is that the molecule itself has nothing exotic about it: it is one of the oldest and best-studied in biochemistry.

What it is, concretely

NAD+ stands for nicotinamide adenine dinucleotide. It is a coenzyme — a molecule without which certain enzymes simply do not work. It is found in every cell with a nucleus in the body.

Its main role is as an electron carrier. In the reactions by which the cell extracts energy from food, NAD+ takes up electrons and becomes NADH; it then passes them on and becomes NAD+ again. This cycle repeats billions of times per second, in the mitochondria.

Without NAD+, cellular respiration stops. That is not a marketing exaggeration, it is textbook biochemistry.

What else it does

Besides its role in energy metabolism, NAD+ is consumed by several families of enzymes — not just recycled:

• sirtuins, involved in regulating gene expression and in the cell's response to metabolic stress;
• PARPs, involved in DNA repair;
• enzymes involved in cell signalling.

Here is the important difference: in energy metabolism NAD+ is recycled, but these enzymes break it down. So the body has to resynthesise it constantly.

Why it declines with age

Measurements in tissues show that NAD+ levels fall with advancing age. Two explanations have been proposed, probably both true: synthesis falls and consumption rises — because DNA damage accumulates, so the PARPs work harder.

What does not automatically follow from this: that restoring the levels reverses ageing. The correlation between falling NAD+ and ageing is well documented. That supplementation produces measurable clinical effects in humans is a separate claim, with a much lower level of evidence.

Where the human evidence stops

What can honestly be said, in September 2026:

• In animals, restoring NAD+ levels has produced results that have rightly excited researchers.
• In humans, studies show that certain forms of administration raise NAD+ levels measurable in the blood. That is established.
• What happens next — whether those levels translate into energy, cognitive function or longevity — does not yet have an answer based on large, long studies.

It is a promising direction of research, not a proven treatment. Anyone who tells you otherwise is selling you something.

What the human studies actually show

The conclusion above is easy to write. It is worth seeing what it rests on:

In 2026, a systematic review gathered 33 human intervention studies. Oral precursors consistently raised NAD+ metabolites and were generally well tolerated, but the effects on functional, metabolic or vascular outcomes were heterogeneous and often null. And, importantly for anyone considering an IV drip: the authors found no study with clinical outcomes that had evaluated NAD+ given intravenously or intramuscularly for longevity or general wellbeing.

Benefits of a NAD+ IV drip: what is realistic and what is merely claimed

A search for "NAD IV drip benefits" leads to long lists. Here is how the same claims look set against the evidence:

What remains realistic: a molecule with an established biochemical role, given at a known dose, predictably, in a medical setting. Not a guaranteed result — and no clinic should sell it to you as one.

Who it makes sense for and who it does not

It may make sense to discuss at the assessment if you are an adult, without a medical problem you are trying to solve with an IV drip, you are interested in longevity as a direction of research, you understand the result is not guaranteed and you prefer a dose given under supervision to a supplement. It does not make sense if:

• you have persistent, unexplained tiredness — it has causes that are investigated, with blood tests and a consultation, not covered up with an IV drip;
• you expect a certain, measurable effect because you read somewhere that there is one;
• you are pregnant or breastfeeding, have severe kidney failure, known allergies to the components or a severe active infection — these are the contraindications we check;
• you have an active heart or cancer condition — situations that do not automatically rule it out, but are assessed individually, by a doctor.

What "NAD therapy" means

In practice, the phrase covers very different things: intravenous NAD+ infusions, injections, oral supplements with precursors, even patches and sprays. They are not equivalent, and the difference between them is bigger than it looks — see NAD supplements or IV drip.

What you feel during the IV drip and why it runs slowly

Given slowly, a NAD+ IV drip is usually uneventful: you sit in a chair with a cannula, and the staff check the rate. Unpleasant sensations are related to speed.

A retrospective analysis published in 2026 compared, in a commercial setting, 500 mg NAD+ infusions with nicotinamide riboside infusions. In the NAD+ group, moderate to severe digestive symptoms, raised heart rate and chest pressure were reported during the infusion; all of them disappeared once it ended. Precisely because of them, NAD+ infusions lasted 97 minutes on average, compared with 37 for nicotinamide riboside. The study is retrospective and preliminary, and the authors worked for the network in which the infusions were given — but it describes exactly what we see too when the rate is too fast.

In practice: if you feel nausea, pressure in your chest or palpitations, say so immediately. The rate is reduced, and in most cases the sensation passes.

How long it takes and how often

• NAD+ 100 mg — about 90 minutes.
• NAD+ 250 mg — two to three hours.
• NAD+ Longevity Complex (NAD+ 100 mg, vitamin C 5 g, glutathione 600 mg) — two hours to two and a half hours.

How often: there is no schedule established by clinical studies because, as we have seen, there are no studies with clinical outcomes for the NAD+ IV drip. For those who choose a series, we have the NAD+ Longevity course, with 4 sessions of 250 mg; the interval between them is set at the assessment, not from a standard calendar.

At Synerva

We give NAD+ intravenously, in doses of 100 or 250 mg, slowly — 90 minutes for the lower dose, up to three hours for the higher one. The slow rate is not a commercial choice: given quickly, NAD+ causes unpleasant sensations — chest pressure, flushing, nausea — which disappear when it is slowed down.

We frame it as a longevity protocol, with the correct wording: it supports cellular energy metabolism, a promising direction in research, with no anti-ageing promises. Details: NAD+ IV drip.

Sources

Safety of beta-nicotinamide mononucleotide (β-NMN) — EFSA Journal, 2026 — safety assessment of a NAD+ precursor, with context on niacin metabolism.

Extension of use of nicotinamide riboside chloride as a novel food — EFSA — assessment of another precursor, with human bioavailability data.

Massudi et al., PLoS One, 2012 — the age-related decline of NAD+ in human tissue (skin).

Clement et al., Rejuvenation Research, 2019 — the plasma NAD+ metabolome by age.

Martens et al., Nature Communications, 2018 — oral nicotinamide riboside, 6 weeks, healthy adults.

Dollerup et al., American Journal of Clinical Nutrition, 2018 — nicotinamide riboside, 12 weeks, men with obesity: no effect on insulin sensitivity.

Grant et al., Frontiers in Aging Neuroscience, 2019 — what happens to NAD+ in plasma and urine during a 6-hour infusion.

Gallagher et al., Ageing Research Reviews, 2026 — systematic review of studies with NAD+ and precursors, in humans and animals.

Reyna et al., Frontiers in Aging, 2026 — tolerance of NAD+ infusions compared with nicotinamide riboside, retrospective analysis.

Elhassan et al., Cell Reports, 2019 — oral nicotinamide riboside and the muscle NAD+ metabolome, in 12 older men.

For information only. It does not constitute a treatment recommendation; the protocol is decided at the medical assessment.