NAD+ (nicotinamide adenine dinucleotide) has become one of the most talked-about molecules in wellbeing, longevity, and energy circles. Search interest in "NAD+ for energy" and "NAD+ anti ageing" has grown quickly, and it is easy to see why: the underlying biology is genuinely interesting, and it touches processes that matter as we age. But interest and marketing enthusiasm are not the same as proof. This article looks honestly at what the evidence does and does not show, so you can form a realistic view.

If you are new to the topic, it may help to first read What is NAD+? for the basics before diving into the evidence here.

Why NAD+ is linked to energy and ageing biologically

The biological rationale for NAD+ is well described, and this is the strongest part of the story. NAD+ is a coenzyme found in every cell in the body, and it plays a central role in energy metabolism. Inside your mitochondria, the tiny structures that act as your cells' power plants, NAD+ shuttles electrons through the reactions that convert food into usable energy (ATP). Without adequate NAD+, these reactions simply cannot run efficiently. This is why NAD+ is so often framed in terms of "energy" at a cellular level.

NAD+ does more than fuel metabolism, though. It is a required substrate for two families of enzymes that have attracted a lot of scientific attention. The first are the sirtuins, which help regulate how cells respond to stress and are involved in processes linked to healthy ageing in laboratory models. The second are the PARP enzymes, which help repair damaged DNA. Because both sets of enzymes consume NAD+ to do their work, NAD+ sits at a genuinely important crossroads of energy production, cellular stress responses, and DNA repair.

There is also a widely reported observation that tissue NAD+ levels tend to decline with age in many organisms. If NAD+ falls and it is needed for energy, repair, and sirtuin activity, the reasoning goes, then topping it back up might support healthier ageing. That is a plausible and appealing hypothesis. It is worth being clear, however, that a plausible mechanism is a starting point for research, not a conclusion. The history of medicine is full of sensible-sounding mechanisms that did not deliver the expected benefits when properly tested in people.

What preclinical (animal and cell) studies show

Much of the excitement around NAD+ comes from preclinical research: studies in isolated cells and in animals such as mice and worms. In these settings, strategies that raise NAD+ levels, often using precursors like NMN (nicotinamide mononucleotide) or NR (nicotinamide riboside), have been reported to improve various markers. Depending on the model, researchers have described effects on mitochondrial function, insulin sensitivity, exercise capacity, and certain measures associated with ageing in those organisms.

These findings are scientifically valuable, because they help explain how NAD+ works and generate hypotheses worth testing. But there is an important caveat that applies to this entire field, and indeed to most of biology: results from cells and animals do not always translate to humans. Mice are not small people. They have different metabolisms, different lifespans, and are usually studied under highly controlled conditions that do not reflect ordinary human life. Many interventions that look striking in a mouse show little or no effect when carefully tested in humans.

So the honest summary of the preclinical evidence is this: it is encouraging and it is substantial, but on its own it cannot tell us whether raising NAD+ meaningfully improves energy or slows ageing in people. For that, we need human trials.

What human trials show so far, and their limits

Human research on NAD+ and its precursors does exist, and it is growing. Several small clinical trials have tested NAD+ precursors in people and looked at outcomes such as blood NAD+ levels, metabolic markers, physical performance, and safety. A reasonably consistent theme is that oral precursors can raise measured NAD+ levels in the blood, and that they have generally been reported as reasonably well tolerated over the short periods studied.

The limits, however, are considerable and worth stating plainly:

  • The trials are mostly small. Many have involved only a few dozen participants, which makes it hard to detect modest effects or rare risks with confidence.
  • They are mostly short. Ageing plays out over decades. Studies lasting weeks or a few months cannot tell us much about long-term ageing outcomes.
  • Raising a blood level is not the same as a health benefit. Showing that NAD+ levels rise is a biochemical result. It does not automatically mean people feel more energetic, live longer, or age more slowly.
  • Meaningful ageing outcomes have not been established. There is currently no robust human trial evidence that any NAD+ product slows human ageing or reliably increases everyday energy in healthy adults.

None of this means NAD+ research is a dead end. It means the field is still early, and the questions that matter most to people, including whether these products make a real difference to how you feel and age, remain genuinely open. Larger, longer, well-designed trials are needed before firm conclusions can be drawn. In the UK, bodies such as NICE assess treatments against this kind of high-quality evidence before recommending them, and NAD+ products for ageing or fatigue have not reached that bar.

Separating marketing claims from the evidence

This is where honesty matters most. Because the biology is compelling and the word "longevity" is powerful, NAD+ is sometimes marketed with far more confidence than the human evidence supports. It is worth learning to spot the gap.

Be cautious of any claim that a NAD+ product is a proven way to reverse ageing, dramatically boost energy, or deliver a specific result within a set timeframe. Firm promises of reversed ageing or a definite energy boost are not supported by the current evidence, and confident-sounding assurances of a certain outcome should be treated with real scepticism. Watch out, too, for the leap from mechanism to outcome, phrases like "NAD+ powers your cells, so this will give you more energy." The first half describes real biology; the second half is an assumption that has not been reliably demonstrated in people. Testimonials and dramatic single-person stories are also worth taking with caution, because they are not the same as evidence from a properly designed trial, and they can make an unproven effect feel more certain than it is.

It is also important to understand the UK regulatory position. No NAD+ product is licensed by the MHRA to treat ageing, fatigue, or any disease. Products are generally offered as supplements or wellbeing treatments rather than as medicines with an approved therapeutic claim. Reputable UK providers must operate under GPhC and advertising standards that prohibit unsupported health claims, which is one reason careful providers describe NAD+ in measured terms rather than promising outcomes.

Farmeci does offer NAD+ through its online clinic, including an injectable NAD+ option, but the focus of this article is deliberately on the evidence rather than on any product. If you are weighing up different formats, our comparison of NAD+ injections vs IV vs oral explains how they differ in practical terms.

Sensible expectations, and when to speak to a clinician

So where does this leave you? A balanced view is that NAD+ is a genuinely important molecule with a well-understood role in energy and cellular maintenance, and that raising NAD+ is a legitimate and active area of research. At the same time, the human evidence is not yet strong enough to promise improvements in energy or slower ageing, and anyone claiming otherwise is running ahead of the science.

Setting sensible expectations helps. If you choose to explore NAD+, it is reasonable to view it as something being studied for potential wellbeing support, not as a proven energy fix or anti-ageing treatment. It is also worth remembering the less glamorous but far better-evidenced foundations of energy and healthy ageing: regular physical activity, good-quality sleep, a balanced diet, not smoking, and managing stress. These have decades of solid human evidence behind them.

Persistent tiredness is also worth taking seriously rather than self-treating. Ongoing fatigue can have many causes, some of them straightforward to identify and address, such as low iron, thyroid problems, poor sleep, or low mood. Reaching for a supplement can sometimes delay finding out what is actually going on. If you feel constantly low on energy, speaking to your GP or an NHS service is a sensible first step.

If you are considering NAD+ specifically, it makes sense to do so with professional input rather than on the strength of marketing alone. A clinician can talk through your medical history, any medicines you take, and whether an option is appropriate for you, and can set realistic expectations about what is and is not known. If you want to understand the practical side, our guide to NAD+ injections: safety and side effects is a useful companion. Ultimately, a UK-registered clinician will advise based on your individual circumstances, which is the right footing for any decision about your health.