NAD+ Supplements: The NAD Really Does Go Up. Almost Nothing Else Did.

Let us start with the part that is true, because it is unusual for a supplement and it deserves saying first.

NAD+ boosters raise NAD+. Across the human trials, oral nicotinamide riboside and nicotinamide mononucleotide “consistently demonstrated biochemical target engagement” — the molecule they are supposed to raise goes up, reliably, and they were well tolerated. [1]

Then the review gets to what happened to the people. Effects on function, metabolism, blood vessels and other healthspan-relevant outcomes were “heterogeneous and often null or endpoint-specific”. [1]

A number moved. Almost nothing else did.

Eighty of the 113 studies were in rodents

The review ran from January 2010 to October 2025 and found 113 eligible studies. Thirty-three were human intervention studies, 28 of those randomised. The other eighty were rodent studies. [1]

And in rodents it looks great. NAD+ augmentation was “frequently associated with improvements in metabolic, mitochondrial, inflammatory, and functional outcomes”, though even there the reviewers note effects varied across models. [1]

This is the oldest story in supplement marketing and it never stops working: the mouse data is spectacular, the human data is a shrug, and only one of those makes it onto the label.

On metabolism specifically, eight trials found nothing

Because this is a body composition site, the metabolic question is the one we care most about. There is a meta-analysis for it.

Eight randomised trials, 342 middle-aged and older adults, doses from 250 mg to 2,000 mg a day for up to twelve weeks. [2]

Fasting glucose: no significant benefit. Fasting insulin: none. Glycated haemoglobin, which reflects blood sugar over months: none. Insulin resistance: none. Lipid profile: none. [2]

Every marker they looked at, and nothing on any of them. The authors are careful to note this is a small number of trials in relatively healthy people — a fair caveat, and it cuts both ways, because relatively healthy people are exactly who is buying this.

Now the drip, which is the expensive end

NAD+ is also sold as an intravenous infusion in wellness clinics, at a price that makes a tub of powder look like pocket change.

Here is what the review found on that, in full: “No eligible outcomes trials evaluated intravenous or intramuscular NAD+ itself for anti-aging or wellness indications.” [1]

Not weak evidence. Not mixed evidence. None.

There was one non-randomised intravenous NMN study, which the reviewers say “primarily contributed short-term safety and biomarker information”, and one intravenous NAD+ pharmacokinetic pilot with no eligible clinical outcomes, counted as context only. [1] That is the entire evidence base for an infusion you sit in a chair for.

The verdict

Unsupported — for the benefit, not for the biochemistry.

Be precise about that, because the distinction is the whole page. The supplement does the molecular thing it claims to do, and does it consistently. That is more than most supplements can say.

What has not been shown is that raising the number changes anything you would notice. The reviewers’ own word for the clinical effectiveness is “inconclusive”, and we are not going to be more confident than they were. [1] But twenty-eight randomised human trials have now been run, the downstream results were often null, and the one meta-analysis on metabolic markers found nothing on any of them.

This is not a case of nobody having looked. People looked.

And if you are considering the intravenous version, the honest summary is that you would be the trial.

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