NMN and NAD+ Supplements: What the 2026 Trial Actually Showed

1. Why is NAD+ suddenly everywhere?

NAD+ is a molecule your cells use to turn food into energy. It is involved in hundreds of reactions, including DNA repair. Levels appear to fall as we get older. That single fact is the foundation the entire longevity category is built on.

The pitch follows naturally. Top the molecule back up and you slow the clock. It is a tidy story, and in mice it has produced striking results. One researcher quoted by NPR put the gap plainly: in rodents, NAD+ looks miraculous. In humans, that has not been shown.

You cannot usefully swallow NAD+ itself, because it is poorly absorbed. So supplements sell precursors instead. The three that matter are nicotinamide mononucleotide (NMN), nicotinamide riboside (NR) and plain nicotinamide (a form of vitamin B3). All three are vitamin B3 derivatives.

2. What did the 2026 trial actually find?

Until this year, nobody had compared the three head to head in people. The January 2026 study did exactly that. It was a randomised, open-label, placebo-controlled trial in 65 healthy adults, who took one of the three precursors or a placebo once daily for 14 days.

Two findings stand out. First, NMN and NR both raised whole-blood NAD+ over the fortnight, by a similar amount. Plain nicotinamide did not. That is a genuine answer to a question the supplement industry had been arguing about for a decade.

Second, and more surprising, the route runs through your gut. The authors found the effect depends on gut bacteria converting the supplement into nicotinic acid, which your tissues then use to build NAD+. Your microbiome is part of the machinery. That implies the response could vary quite a lot from person to person.

3. What the trial never measured

This is the part that gets lost. The study measured NAD+ and related chemicals in blood. It did not measure whether anyone had more energy, slept better, aged more slowly or improved a single marker of health.

That distinction matters more than it sounds. Raising a number in the blood is a surrogate endpoint. It is a stand-in for the thing you actually care about. Medicine is full of surrogates that moved beautifully while the outcome underneath refused to budge. CoQ10 is the contrast: its trials did ask people about tiredness, as our guide to CoQ10 for tiredness explains.

So the honest summary is narrow but real. NMN and NR reliably raise NAD+ in healthy adults. Whether that does anything for you is still unknown.

4. NMN, NR or plain vitamin B3?

• NMN and NR performed the same. Paying a premium for one over the other is not supported by this trial.
• Cheap nicotinamide is not a substitute. It did not produce the sustained rise the other two did.
• Dose claims are unanchored. No trial has established the dose that delivers a health benefit, because no trial has established the benefit.

It is also worth remembering what these compounds are. They are derivatives of a vitamin most of us already get enough of. The NHS is direct about the parent nutrient.

“You should be able to get all the niacin you need from your daily diet.”

— NHS, B vitamins and folic acid

The NHS also notes that high doses of nicotinic acid supplements can cause skin flushing. Safety in the published NAD+ trials has looked reassuring so far. But these are short studies, and nobody has run a multi-year one. If you take medication or have a liver condition, speak to a qualified clinician first. The gram doses used for cholesterol are a separate question again, covered in our guide to niacin, cholesterol and Lp(a).

5. Is NMN safe, and is it legal in the UK?

Side effects look mild so far. A 2026 review pooled 15 trials of NMN in adults, at 250 to 2,000 mg a day for up to 24 weeks (Yang et al., Nutrients 2026). NMN did not raise the rate of side effects. Nor did it push up ALT or AST, the two liver enzymes a blood test uses to spot strain on the liver.

The same review looked for benefits and found very few. Weight, fasting blood sugar, HbA1c and cholesterol did not change. Diastolic blood pressure, the lower of the two numbers, dipped slightly. No trial ran past six months.

The legal position is less well known. NMN is a novel food: it was not eaten much in the UK or EU before May 1997. So it needs approval before it can be sold as a supplement.

The Food Standards Agency has not given that approval. Its register shows the NMN application still at the risk assessment stage. NR, the other booster in the trial, is authorised in Great Britain at up to 300 mg a day for adults.

6. Can you test your NAD+ level in the UK?

Not in any meaningful way, and we would rather say so than sell you something. NAD+ is unstable in a blood sample and is measured with specialist research methods. It is not a routine UK laboratory test, and Helvy does not offer it.

Even a perfect NAD+ reading would not tell you much. No agreed healthy range exists, and no outcome has been tied to a given level. You would have a number without a meaning.

7. The markers worth measuring instead

Here is the useful move. Several markers do track how your body is ageing, they are measurable today, and each one has decades of outcome data behind it. If longevity is the goal, this is where the evidence actually sits. The same test-first logic applies to lithium orotate, the other longevity supplement of the moment.

• ApoB. A count of the cholesterol-carrying particles that drive artery furring. It is a sharper read than standard cholesterol testing. See our ApoB guide.
• Lp(a). An inherited risk marker you only need to check once. Most GPs never run it. Our Lp(a) guide explains why it matters.
• hs-CRP. A sensitive marker of the low-grade inflammation linked to ageing. The CRP guide covers how to read it.
• Your full lipid picture. LDL, HDL, triglycerides and non-HDL cholesterol, read together rather than one at a time.

Helvy's Advanced Heart Health panel (£159) covers ApoB, Lp(a) and hs-CRP alongside the full cholesterol picture. It is a home finger-prick test processed by UKAS-accredited UK laboratories, with results in around 5 working days. Our heart health hub and longevity blood tests guide go deeper on how these markers fit together.

None of this is an argument against trying NMN. It is an argument for knowing your starting point first. If your ApoB is high or your hs-CRP is raised, that is a lever with real evidence behind it, and it is one you can actually watch move.

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