Have you heard any of the buzz about NAD supplements? NAD is a molecule that sits at the heart of energy production and DNA repair. Our levels of NAD can decline with age, which has led to the idea that this could be one cause of many age-related diseases, chronic inflammation and cognitive decline. Enter the concept of boosting NAD levels by supplementing with NAD itself or its precursors, called NMN and NR. In this post, I’ll explain what the NAD family of molecules are and critique the clinical evidence to see how it stacks up in relation to the health claims.
NAD (nicotinamide adenine dinucleotide) is getting a lot of attention as the next big anti-ageing supplement. The reason why is that NAD is a critical component of how we generate cellular energy, repair DNA and regulate biological pathways linked to ageing. We make NAD naturally in our bodies from the B-group vitamin niacin, or we can produce it from the amino acid tryptophan.
Levels of NAD can decline with age, which has fuelled interest in how supplementation with NAD may help with ageing, especially considering NAD’s central role in energy production and cellular repair.
Falling NAD levels with age are explained by lower rates of its biosynthesis together with increased demand because of its importance in so many cellular reactions. Tissues such as the brain, heart and muscle have high metabolic demands so need a lot of NAD. And it is these same tissues that show the greatest signs of defects with ageing which increases our risk of dementia, heart disease and loss of muscle mass and strength.
But it is important to say straight out that just because NAD levels fall with age doesn’t automatically mean it is the reason for many of the health problems that occur with ageing. Wrinkles are certainly a sign of ageing, but we don’t say that wrinkles cause many of the health problems of ageing. So, is there any truth to the NAD supplementation and healthy ageing story? Time to dive in further.
Let’s look firstly at the different ways that NAD levels can be boosted with supplements. Now, don’t go looking for a bottle of NAD at your local health supplement store because the oral form of NAD has poor absorption and tends to be broken down in the gut. Instead, the popular ways to try and boost NAD levels come from taking its precursors. Two of the more popular ones are NMN and NR.
NMN supplements
NMN stands for nicotinamide mononucleotide, and it is the direct metabolic precursor to NAD. You’ll find NMN naturally in small amounts in foods like avocados, broccoli and tomatoes, but at levels much lower than what have been used in supplementation clinical trials.
At least in animals, NMN supplementation seems to improve mitochondrial function, improve insulin sensitivity and support cardiovascular and cognitive health. In human clinical trials, there is research that shows that it increases physical ability in older people as well as improves markers of vascular health. Don’t get too excited because the effects when they are seen are very modest and usually are not statistically significant.
In a recent review of the clinical trials with NMN, there was very little benefit seen on blood glucose and lipids despite blood levels of NAD being clearly elevated. The authors of the review went on to say that the wider claimed benefits of NMN supplementation are exaggerated. I would completely agree with this.
So, while it’s great news if you’re a rodent that taking NMN can be of benefit, the different physiology of humans and the overly cautious need to use lower doses of NMN in human trials means that the potential benefits are smaller.
Interestingly, prior to December of 2025, NMN was illegal to be sold commercially in Australia, but the TGA has now reversed their stance and it is approved for sale. In the United States, up until October of 2025, it was technically banned, but the FDA has just changed their assessment and NMN can now lawfully be sold as a supplement.
NR supplements
The legal status of another NAD precursor called NR (nicotinamide riboside) is clear. NR is approved for commercial sale in both Australia and the United States and has been for some time.
Just like the case for NMN, animal studies with NR point to a benefit for ageing, but the human clinical trials have yet to show any robust anti-ageing effects, with very mediocre results in the few trials done so far.
A nice summary of the NR research field was given in a 2023 review paper that could critically assess 25 human clinical trials. The conclusion? Let me quote directly from the paper: “Collectively, oral nicotinamide riboside supplementation has displayed few clinically relevant effects, and there is an unfortunate tendency in the literature to exaggerate the importance and robustness of reported effects.” So, there you have that word ‘exaggerated’ again, and just like for NMN, a clear case of hype over real substance at this stage.
Intravenous NAD?
One final way to boost NAD levels is by IV therapy where NAD is given directly via a line into the body. Such a method is expensive and is linked to unpleasant side effects like nausea and chest discomfort. There is still a big question mark over the clinical benefits for anti-ageing using this method.
NAD supplements for muscle mass and function
Losing muscle mass and function is one of the hallmarks of ageing and physical decline. Can NAD supplements help here? Just recently, a review looked at the evidence for taking NMN or NR for its effect on muscle mass and function. And even though the review could include 10 clinical trials with a mostly older population group who should benefit the most from the supplements, the review found little evidence for a benefit on muscle strength or physical function.
It could be that any benefit of NAD supplements on muscle was too small to measure. Or perhaps it also needs exercise to go with it considering most of the trials didn’t include an exercise intervention. But we already know that exercise will have a clear benefit on muscle even without NAD supplements.
So yet another strikeout for the ‘exaggerated’ health claims made about NAD-boosting supplements. They are not a panacea for the metabolic ravages of ageing.
Could there be other benefits of NAD supplements?
Emerging research has explored the potential of NAD precursors in supporting cognitive health, particularly in the context of neurodegenerative diseases. Preclinical studies suggest that boosting NAD levels may enhance neuronal resilience and reduce neuroinflammation, mechanisms implicated in conditions such as Alzheimer’s and Parkinson’s disease.
However, human trials remain limited and have yet to demonstrate clear cognitive benefits from NMN or NR supplementation. So the evidence is insufficient to support widespread use for neuroprotection at this time.
Interestingly, both NMN and NR can selectively stimulate the growth of beneficial bacteria such as Bifidobacterium and Lactobacillus. These genera of bacteria are linked with improved gut health, including improved gut barrier function, reduced inflammation and immune system support. So, this could be one of the mechanisms through which NMN and NR supplements could offer a health benefit. But I could list hundreds of beneficial food components that can favourably alter the gut microbiome, so it is hard to get too excited about this link with NAD precursors considering the cost of the supplements.
What it all means
What to make of all this? Taking NR and NMN supplements will certainly increase NAD levels in humans, but whether this translates into a meaningful clinical benefit is still unclear. Most clinical trials are small, short-term, and often underpowered to detect meaningful clinical outcomes. Add to this the substantial variability in dosing regimens, study populations, and outcome measures, which makes it difficult to draw firm conclusions about health benefits.
Both NMN and NR are generally safe to take at recommended doses as no serious adverse health problems have been reported in clinical trials, but long-term effects require further study. There are still some unanswered safety questions, especially for supplements promoted for their longevity benefits, which would necessitate taking them for many years.
But do you want to know one surefire way to increase your NAD levels naturally? It’s exercise. How it does this is quite simple: the more exercise you do, the more NAD you produce to meet the energy demands. If the health benefits of regular exercise could be put in a pill, then it would be the biggest-selling supplement of all time. Exercise dramatically and consistently cuts the risk of all the metabolic changes and diseases that are linked to ageing, be it in our brain, muscles or blood vessels. And that’s not an exaggeration.
In the quest for longer, healthier lives, the allure of reaching for the latest supplement is strong. Research into the NAD pathway and how to boost this with supplements is ongoing, but for now, the evidence for a meaningful benefit is mostly unproven. And where benefits have been found, they are marginal at best and don’t really stack up to the huge benefits you can bank by getting the foundations right of regular exercise, good nutrition and quality sleep.
Leave a Reply