NAD+ occupies an unusual position in the wellness market. The underlying biochemistry is textbook material, uncontroversial and taught to undergraduates. The claims built on top of it range from the cautious to the absurd. Separating the two is harder than it should be, largely because the settled science is repeated accurately and then used as a runway for conclusions it does not support.
What is established
Nicotinamide adenine dinucleotide is a coenzyme present in every cell in the body. It participates in redox reactions central to cellular energy metabolism, and it serves as a substrate for several classes of enzyme involved in DNA repair and cellular signalling. None of this is contested.
It is also well established that NAD+ concentrations in human tissue decline with age. This has been observed across multiple tissue types and is not seriously disputed.
Those two facts, taken together, are the entire legitimate foundation of the NAD+ supplementation field. They establish that a molecule with important cellular functions becomes less abundant over time. They do not, by themselves, establish that raising its concentration produces any particular outcome in a person.
Where the inference gets stretched
The step from “this declines with age” to “restoring it reverses the effects of ageing” is a large one, and it is routinely taken without acknowledgement. Many things decline with age. Some of those declines are causes of the problems associated with ageing, some are consequences, and some are neither.
Research into whether NAD+ precursor supplementation produces measurable clinical benefit in humans is genuinely active, and it has produced some interesting findings alongside a good deal of ambiguity. The honest summary is that the field is at the stage of asking whether an effect exists and under what conditions, not at the stage of quantifying a reliable benefit. Anyone presenting it as settled is ahead of the evidence.
This is not an argument that NAD+ supplementation is worthless. It is an argument that the confident claims attached to it in marketing materials are not supported by the literature those materials gesture at.
Why delivery route became a marketing battleground
A second layer of overstatement concerns how the compound is administered. Intravenous, subcutaneous, intranasal and transdermal routes are all offered commercially, usually with claims about bioavailability that are stated more precisely than the evidence allows.
There are real pharmacokinetic differences between routes, and bypassing first-pass metabolism is a genuine consideration. But the confident percentages that appear in promotional material for these products are generally not traceable to published comparative studies in humans. Patients encountering a specific bioavailability figure should ask where it comes from, and treat an unsourced number as marketing.
Among US telehealth providers, HealSend prescribes NAD+ injections alongside intranasal and transdermal formats, and states plainly on its own materials that it does not claim a specific outcome from NAD+ therapy. That restraint is unusual enough in this category to be worth noting as a point of comparison rather than as an endorsement.
What a reasonable patient conversation looks like
A clinician discussing NAD+ with a patient honestly has to hold several things at once.
The biochemistry is real and interesting. The age-related decline is real. The clinical benefit in humans is an open question rather than a demonstrated fact. The safety profile of the compound in the formats commonly offered is reasonably well tolerated but not risk-free, and injection-site reactions are the most commonly reported effect with subcutaneous administration. And the patient’s own history, current medications and pregnancy status all bear on whether it is appropriate for them at all.
That is a more complicated message than the one the market delivers, and it is the one a licensed clinician should be delivering after reviewing an individual’s history rather than in a promotional page.
How to read a provider’s claims
Three signals distinguish a provider describing the compound accurately from one selling a story.
Does it name a specific outcome? Claims of reversed ageing, restored youthful energy or quantified cellular repair are ahead of the evidence.
Does it cite a bioavailability figure without a source? If a percentage appears with no study behind it, it was chosen rather than measured.
Does a licensed clinician review the patient before anything ships? NAD+ products are dispensed through telehealth providers on a clinician’s prescription. A seller who skips that step has removed the only part of the process that is about the individual patient.
The position worth holding
NAD+ is a legitimate subject of ongoing research and an area where the commercial claims have run well ahead of the findings. Both of those are true simultaneously, and a patient is best served by a provider willing to say so.
The question for anyone considering it is not whether the biochemistry is real, because it is. It is whether a specific product, by a specific route, produces a benefit that anyone has actually demonstrated. On that, the honest answer today is that the work is still in progress.