What is NAD+ inside a cell, and what is on the price list
Nicotinamide adenine dinucleotide is not a peptide. It is not synthetic in origin, it is not new, and it was not invented by anyone selling it. It is a small molecule that carries electrons through the reactions turning food into usable energy. It is also consumed as a raw material by enzymes involved in DNA repair and in switching genes on and off. Cells make it, spend it, break it down and rebuild it, continuously.
Because it is central to metabolism, and because measured levels appear lower in older tissue than younger tissue in both animals and people, it became a commercial target. The question worth asking is not whether the molecule matters. It obviously does. The question is whether the particular product in front of you raises it, and whether raising it changes anything a person would notice.
Inside a cell it is a working part, not a supply. It cycles between two forms as it accepts and hands off electrons, thousands of times over, and the pool is replenished mainly by a recycling route that rebuilds it from a breakdown product rather than by making it from scratch. The body also builds it from tryptophan in food and from the vitamin B3 family.
On a price list, the same three letters mean a bag of fluid hung on a stand for an hour or more, or a small vial, or a capsule containing something that is not the molecule at all but a precursor to it. These are separate products with separate evidence behind them, and the abbreviation hides that.
Four products sold under one abbreviation
Read the third column across. The body of human research that gets quoted in this market was, for the most part, generated by giving people an oral precursor. The product with the highest price and the most clinical staging around it, the infusion, has the thinnest human evidence of the four.
That is not an accusation of dishonesty. A clinic can quote precursor trials accurately and never say a false sentence. The substitution happens in the reader, who hears a large research literature and looks at the bag on the stand.
| What is sold | What is actually in it | Which intervention the published human trials mostly studied | What a buyer can verify |
|---|---|---|---|
| Oral capsule of nicotinamide riboside or nicotinamide mononucleotide | A precursor, not the coenzyme | This one, in humans, orally, across a reasonable number of trials | Label claim only, unless independently tested |
| Intravenous infusion | The coenzyme itself, in solution | Very little, and far less than the precursor work | Nothing about identity or sterility without the clinic's own records |
| Subcutaneous injection from a research supplier | Usually the coenzyme, unverified | Effectively none in people | Nothing |
| Nasal spray or patch | Varies, often unstated | None worth citing | Nothing |
The step between a swallowed precursor and a raised coenzyme
A precursor is a starting material. Nicotinamide riboside and nicotinamide mononucleotide are taken by mouth, absorbed, and converted inside cells into the coenzyme through the recycling route.
Human trials of oral precursors have repeatedly shown one thing clearly: blood levels of the coenzyme go up. That result has been reproduced in people by more than one group, and anyone who tells you the whole field is unsupported is overstating. It is a real, measurable, replicated human finding.
What those same trials have not consistently shown is that anything a participant would recognise improves as a result. Trials of oral precursors in humans have looked at things like physical performance, insulin sensitivity, inflammatory markers and measures of muscle function, and the results across them are mixed rather than uniform. A raised blood level is a biomarker. It is the first step in an argument, not the conclusion.
Why the route of administration is the whole argument
Injecting the finished coenzyme instead of a precursor sounds like a shortcut, and this is where an honest account has to admit an open scientific question rather than pretend to a verdict.
The coenzyme is a charged molecule, and whether it crosses into cells intact is genuinely debated among researchers. One well supported view is that circulating coenzyme is broken down outside cells into smaller pieces, which are then taken up and reassembled inside. If that is what happens, an infusion is an expensive and slow way of delivering precursors, and the argument for the drip over the capsule weakens considerably.
This is not settled, and a page claiming it is settled in either direction is telling you more about its commercial position than about the biology. What can be said with confidence is that the shortcut is assumed rather than demonstrated, and that nobody selling an infusion has published the work that would demonstrate it.
Where the money in an infusion session actually goes
Infusion sessions are typically long, and they are long for a specific reason: giving the solution quickly is reported by providers themselves to cause nausea, flushing and chest tightness, so the rate is kept low. Much of what you pay for is a chair, a nurse and time.
Some of that has real value. A trained person placing a cannula, watching you, and stopping if you react badly is a genuine service, and it is worth more than a vial posted to your door with no supervision at all. Being clear about that is only fair.
What the fee cannot buy is an approved use. Injected NAD+ holds no marketing authorisation anywhere, so no regulator has assessed a manufactured version of it, agreed what it is for, or defined an amount. There is no patient leaflet listing its known harms, because no authority has compiled one. There is no recall route. If you have an unusual reaction weeks later, there is no system collecting it, which means it will not be counted and nobody after you will be warned.
Reading a provider's citation list with one question in hand
Most clinic pages and supplier pages carry a list of references, and the list is usually real. The papers exist, the journals exist, and the findings are described more or less accurately. Checking whether a citation is genuine is therefore the wrong test, because it almost always passes.
The question that separates the useful references from the decorative ones is narrower: what was given, to what, and by which route. Ask it of every line. A trial that gave an oral precursor to people tells you about an oral precursor in people. A study that added the coenzyme to cells in a dish tells you about cells in a dish. A study in mice tells you about mice, and mice differ from humans in exactly the metabolic pathways at issue here.
Run that filter down a reference list on a drip clinic's site and the number of entries that describe an infusion given to a person, with an outcome that person could feel, tends to fall to nearly nothing. The list is not fabricated. It is simply about a different intervention from the one being sold, and no line on it has to be wrong for the overall impression to be.