As more people look for ways to stay younger for longer, the supplement industry has moved beyond creams and cosmetic fixes to something more ambitious: products that claim to slow ageing by acting on cellular processes.
Among the most heavily marketed compounds are NAD+, NMN and resveratrol, often described as supporting cellular repair, energy production and healthy ageing. But what do they actually do, where are they being used, and how strong is the evidence?
To make sense of the claims, it helps to separate three things: the molecule NAD+, the compounds sold to raise it, and the products, such as supplements, creams and serums, that contain them.
Nicotinamide adenine dinucleotide, or NAD+, is a coenzyme found in all living cells. A coenzyme is a helper molecule that allows enzymes to carry out chemical reactions in the body. NAD+ plays an essential role in energy metabolism, DNA repair, inflammation and the activity of a family of proteins involved in cellular stress responses.
NAD+ levels tend to decline with age, although this decline is complex and may vary between tissues. Lower NAD+ availability has been linked to reduced mitochondrial function, meaning reduced activity in the cell structures that help produce energy. This is one of the biological changes associated with ageing.
NAD+ in creams and serums
NAD+ has begun appearing in skincare creams and serums, but the evidence is even less developed here than it is for supplements.
While NAD+ is important for skin-cell energy and repair, it remains unclear whether topical NAD+ in ordinary creams can penetrate the skin in sufficient amounts to produce meaningful anti-ageing effects.
Better-established ingredients, such as sunscreen, retinoids and niacinamide, currently have much stronger evidence for improving visible signs of skin ageing.
NAD+ precursors as supplements
Because NAD+ itself is not thought to be absorbed efficiently when swallowed, much research has focused on NAD+ precursors. Precursors are compounds the body can convert into another substance. In this case, they are compounds the body can convert into NAD+. Two of the best known are nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR).
In animal studies, NAD+ precursors have produced promising results. Older mice given these compounds have shown improvements in energy metabolism, insulin sensitivity and aspects of physical function. Some studies have also reported improvements in healthspan and lifespan-related measures in animal models, although these findings vary by model and do not translate neatly into humans. These results have helped drive enormous commercial interest, but turning promising mouse studies into meaningful benefits for people has proved far harder.
Human clinical trials suggest that NMN and NR can raise NAD+ levels, or related markers of NAD+ activity, in blood and tissues. However, the strongest evidence is for changes in blood, while evidence for meaningful effects in specific tissues is still limited.
Some small studies have reported possible benefits for metabolic health, including insulin sensitivity in specific groups. Others have explored potential effects on muscle mass, but recent reviews have not found convincing evidence that NMN or NR preserve muscle mass or function in older adults.
When researchers look at outcomes that matter more directly to everyday ageing, such as strength, cognition, frailty or biological age, the picture is much less clear. Biological age is a contested estimate of how old the body appears at a cellular or molecular level. One major problem is that ageing unfolds over a long period, while most supplement trials last only weeks or months.
Resveratrol
Resveratrol is another compound often promoted for anti-ageing, but it is different from NMN and NR. It is not an NAD+ precursor. It belongs to a group of natural plant chemicals called polyphenols and is found in red grapes, berries and peanuts.
In laboratory and animal studies, resveratrol has been associated with lower levels of inflammation and improved mitochondrial function, meaning better activity in the parts of cells that help produce energy.
The difficulty is that resveratrol has poor oral bioavailability. This means much of what is swallowed is broken down or modified before it can reach tissues in the form and concentration used in laboratory experiments. This creates a large gap between what resveratrol can do in cells in a dish and what a supplement is likely to do in the human body. So far, human trials have not shown convincing evidence that resveratrol slows ageing, and findings on cardiovascular and anti-inflammatory benefits remain mixed.
Resveratrol may interact with some medications, especially anticoagulant and antiplatelet drugs, often described as blood-thinning medicines. High doses can also cause side effects such as gastrointestinal symptoms. Anyone taking regular medication, managing a chronic condition, pregnant or breastfeeding should seek medical advice before taking high-dose supplements.
So, are NAD+, NMN and resveratrol the elixir of youth? No. The key distinction is between biological plausibility and proven benefit. These compounds are not biologically implausible: they act on real pathways involved in energy production, stress responses and cellular maintenance. But affecting a pathway is not the same as slowing ageing in a person.
In humans, the evidence so far suggests possible benefits in limited contexts, but major questions remain about long-term safety, optimum doses and who is most likely to benefit. The science is plausible, but the marketing often turns “this affects a process associated with ageing” into “this supplement will keep you young”.
For now, the best-supported ways to support healthy ageing remain far less glamorous: regular exercise, good sleep, a balanced diet, avoiding smoking, limiting alcohol and managing long-term health conditions. Supplements may eventually prove useful, but at present, the evidence for staying younger for longer is much stronger for everyday habits than for anti-ageing products.
