Understanding the Biology of Ageing: What Can Slow It Down, and Can NAD+ Supplements Really Help?

Ageing is a natural biological process involving gradual changes to cells, tissues and organs, but research increasingly shows that the rate and effects of biological ageing can be influenced by factors such as exercise, nutrition, sleep and other lifestyle behaviours. This article explores the biology of ageing, the hallmarks of ageing, evidence around longevity advice and the growing interest in anti-ageing supplements such as NAD+. 

The insights provided in this article are from Yusra Serdaroglu Aydin MSc RD, Vivere's Head of Nutrition with a background in nutrition, food engineering and culinary arts. Her approach is grounded in science and shaped by a strong understanding of personalised nutrition and the human microbiome, with a focus on food-first guidance and separating evidence from hype.

The strongest evidence for slowing the effects of biological ageing currently supports exercise, a nutritious diet, good sleep and not smoking, while NAD+ supplements can raise NAD+ but there is limited human evidence that they slow ageing or extend lifespan.

• What causes biological ageing? 

Biological ageing is driven by interconnected cellular changes including DNA damage, mitochondrial decline, epigenetic drift and the accumulation of senescent cells.

• What is the most effective way to slow ageing? 

Building and maintaining cardiorespiratory fitness alongside a healthy diet, not smoking, moderating alcohol intake, sleeping well and staying physically active has stronger evidence for healthy ageing than relying on a single supplement.

• Do NAD+ supplements reverse ageing? 

NAD+ supplements and precursors such as NR can raise NAD+ levels, but current human research has shown modest effects and no proven reversal of ageing or extension of lifespan.

• Can I raise NAD+ without supplements? 

Regular exercise can support natural NAD+ maintenance, with research linking physical activity with muscle NAD+ levels and increased activity of the NAMPT enzyme involved in NAD+ recycling.

• What should I prioritise for longevity? 

Everyday habits that influence several biological processes at once should form the foundation of healthy ageing, with supplements considered an optional extra rather than a replacement for lifestyle measures.

Biological ageing occurs as multiple interconnected processes gradually affect the way cells maintain DNA, produce energy, respond to damage and communicate with one another.

The concept of the hallmarks of ageing provides a useful framework for understanding these processes. Rather than treating ageing as the result of one single cause, the framework describes a collection of biological mechanisms that interact with one another.

The original 2013 framework identified nine hallmarks of ageing, helping researchers organise a complex field of molecular biology into a set of interconnected processes. These included genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion and altered intercellular communication [1].

The framework was expanded in 2023 to recognise twelve hallmarks of ageing, reflecting developments in ageing research and a broader understanding of how biological ageing occurs [2].

The López-Otín framework is particularly useful because it does not simply list things that change with age. A hallmark should meet criteria indicating that it is associated with ageing, that experimentally changing it can accelerate ageing and that modifying it can potentially alter the ageing process.

Genomic instability refers to the increasing vulnerability of genetic material to damage and errors as we age.

DNA is continually exposed to internal and external sources of damage. Cells have sophisticated repair systems to identify and correct problems, but these systems are not perfect. Over time, accumulated damage can affect cellular function and contribute to age-related changes.

Mitochondria are often described as the energy-producing structures within cells and their function becomes increasingly important as we age.

Mitochondrial dysfunction can affect energy production and increase cellular stress. Because mitochondria are involved in many essential cellular processes, mitochondrial decline can influence the function of tissues throughout the body.

Epigenetic changes influence how genes are switched on and off without changing the underlying DNA sequence.

As we age, patterns of gene regulation can change. This process is sometimes described as epigenetic drift and can affect how cells respond to their environment and maintain normal function.

Cellular senescence occurs when cells enter a state where they stop dividing but remain metabolically active.

Senescent cells can accumulate with age and release signalling molecules that influence surrounding tissues. This is one reason senescent cells are an important area of ageing research.

These mechanisms should not be viewed in isolation. DNA damage can influence cellular senescence, mitochondrial dysfunction can contribute to cellular stress and changes in nutrient sensing can affect energy metabolism. The twelve-hallmark framework therefore emphasises the interconnected nature of biological ageing rather than a single root cause.

You cannot currently stop ageing altogether, but evidence suggests that lifestyle behaviours can influence several processes associated with healthy ageing and reduce the risk of many age-related diseases.

The distinction between slowing ageing and preventing ageing is important. Ageing is a normal 

biological process. However, people can influence aspects of their health, physical function and disease risk as they get older.

Lifestyle measures are particularly valuable because one behaviour can affect several biological systems simultaneously. Exercise, for example, can influence cardiovascular fitness, muscle health, metabolic function and mitochondrial biology.

Exercise, diet, not smoking, moderating alcohol intake and good sleep have considerably stronger evidence for supporting healthy ageing than most commercial longevity supplements.

Cardiorespiratory fitness is one of the clearest examples. A large study involving 122,007 adults found that higher cardiorespiratory fitness was associated with lower mortality, with the researchers finding no clear upper limit to the benefit as fitness increased [3].

A separate analysis of more than 750,000 US veterans also found that progressively higher levels of fitness were associated with substantially lower mortality across different age groups and populations [4].

Cardiorespiratory fitness is closely related to the body's ability to use oxygen efficiently. VO2 max is one measure used to assess this capacity. While people have different starting points and physical limitations, improving fitness can be a valuable part of long-term health.

For practical guidance, the NHS recommends that adults aim for regular physical activity across the week, including both moderate or vigorous activity and strengthening exercises [5].

Diet is another important part of healthy ageing. The PREDIMED trial found that a Mediterranean-style diet supplemented with extra virgin olive oil or nuts reduced major cardiovascular events compared with a control diet in people at high cardiovascular risk [6].

Smoking remains one of the clearest modifiable threats to long-term health. Stopping smoking can reduce the risk of serious diseases and is one of the most valuable changes a person can make for their health [7].

Alcohol also deserves consideration. The UK Chief Medical Officers advise that to keep health risks from alcohol to a low level, both men and women should not regularly drink more than 14 units per week [8].

Sleep is similarly important for overall health, although the relationship between sleep and longevity is complex. Consistently getting sufficient, good-quality sleep supports normal physical and cognitive function and forms part of a broader healthy lifestyle.

Autophagy, sirtuin activation and caloric restriction are important areas of longevity research, but promising mechanisms do not automatically translate into longer human lifespan.

Autophagy is a cellular recycling process that helps cells remove and reuse damaged or unnecessary components. It has attracted considerable attention because changes in cellular recycling are associated with ageing and because interventions that influence autophagy have extended lifespan in some animal models.

Sirtuins are another group of proteins involved in cellular regulation. They are influenced by cellular energy status and have roles in processes including gene regulation, stress responses and metabolism.

Caloric restriction has also produced interesting results in laboratory animals. In humans, however, the evidence is more nuanced. The CALERIE trial found that two years of moderate calorie restriction in healthy adults improved several cardiometabolic risk markers, although this does not demonstrate that calorie restriction extends human lifespan [9].

This illustrates an important principle in longevity science: improving a marker associated with ageing is not the same as demonstrating longer life.

“When it comes to longevity, I would always recommend starting with the basics before looking for hacks. Daily movement, a varied whole-food-based diet, adequate protein, good sleep and not smoking have a much stronger evidence base than most longevity supplements. Supplements can have a role, but I see them as an addition to those foundations rather than a substitute for them.”

NAD+, or nicotinamide adenine dinucleotide, is a coenzyme involved in energy metabolism and cellular processes including DNA repair and regulation of cellular stress, but there is currently no evidence that NAD+ supplements reverse human ageing.

NAD+ is found throughout the body and is involved in numerous biochemical reactions. It exists in different cellular forms and participates in the transfer of electrons during metabolic reactions, making it important for mitochondrial energy production.

NAD+ is also consumed by enzymes including sirtuins, SIRT1 to SIRT7, and PARP enzymes. Sirtuins are involved in cellular regulation while PARPs have important roles in responding to DNA damage.

Research indicates that NAD+ availability can decline with age. This has led to significant interest in whether restoring NAD+ levels could influence age-associated cellular changes [10].

The important distinction is between raising NAD+ and reversing ageing. A supplement may increase a biological marker without producing the broad changes required to reverse biological ageing.

Taking NAD+ itself orally is not necessarily equivalent to increasing NAD+ inside cells because NAD+ can be broken down within the digestive system. The delivery method is therefore important. That is why Vivere uses liposomal delivery in its NAD+ capsules, aiming to improve the absorption of NAD+ and reduce its breakdown during digestive transit.

For this reason, much of the current research has focused on NAD+ precursors, which are compounds the body can use to produce NAD+.

Two compounds that have attracted particular attention are nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN).

The research question is therefore not simply whether a product contains NAD+. It is whether the compound reaches the relevant biological pathways, increases NAD+ availability and produces meaningful improvements in health or function.

In Great Britain, the regulatory position differs between NAD+ precursors, food supplements and injectable products, so consumers should check exactly what they are buying and how it is legally supplied.

Nicotinamide riboside has an authorised novel food status for use under specified food supplement conditions. The Food Standards Agency's regulatory information provides a useful starting point when checking novel foods and authorised uses [11].

NMN has a different regulatory position and is not authorised for use in food supplements in Great Britain in the same way as authorised nicotinamide riboside.

The MHRA provides guidance on the supply of unlicensed medicinal products known as "specials" [12].

Consumers should therefore be cautious about claims made online. Prescription-only medicines should be supplied through the appropriate healthcare channels and should not be publicly advertised as though they were ordinary food supplements. A pharmacist or GP can provide appropriate advice where there is uncertainty about a product.

Human clinical trials show that NR and NMN can increase NAD+ availability, but the evidence for meaningful anti-ageing outcomes remains limited and does not currently demonstrate lifespan extension.

One of the largest randomised trials of nicotinamide riboside found that NR increased whole-blood NAD+ levels in a dose-dependent manner, with the highest dose producing an increase of up to 142% [13].

This is important evidence that an NAD+ precursor can affect its intended biological pathway. It does not, however, establish that taking NR makes a person biologically younger.

Another randomised trial found that NR was well tolerated, increased NAD+ and was associated with modest reductions in blood pressure and arterial stiffness [14].

Other research has been less encouraging. One NR trial found that although NAD+ metabolites increased, there were no significant improvements in insulin sensitivity or lipid measures [15].

Together, these findings demonstrate the gap between a measurable molecular effect and a clinically meaningful outcome.

Exercise may support the body's own NAD+ maintenance systems, providing a biological reason to prioritise movement before considering NAD+ supplements.

Research in physically active older adults found that higher muscle NAD+ was associated with physical activity and better muscle function [16].

Another study found that exercise training increased NAMPT, an enzyme involved in the NAD+ salvage pathway that helps recycle NAD+ in muscle [17].

This does not mean exercise works by simply increasing one molecule. Physical activity has wide-ranging effects on cardiovascular health, muscle function, metabolic health, mitochondrial function and physical fitness.

“Movement is one of the most accessible ways to support the biology behind healthy ageing. Exercise can support NAD+ pathways while also improving cardiovascular fitness and muscle function. For me, that makes movement an important step to consider before adding supplements.”

The distinction between animal and human evidence is particularly important. Laboratory studies can investigate specific pathways under tightly controlled conditions. Human ageing is considerably more complex and influenced by genetics, environment, behaviour, nutrition, physical activity, sleep and disease.

A supplement can therefore produce a promising molecular change without necessarily producing the dramatic anti-ageing effect suggested by marketing.

NAD+ precursors can be considered an optional extra by some people, but they should not be treated as an anti-ageing shortcut or a proven treatment for ageing.

The current evidence gives us a reasonable basis for saying that compounds such as NR can raise NAD+ levels in humans. It gives us much less evidence for saying that they slow biological ageing, reverse age-related decline or extend human lifespan.

This distinction matters when interpreting longevity products.

If a product increases NAD+, that is a measurable biochemical effect. If a product improves a health outcome, that is more clinically meaningful. If a product extends a healthy human lifespan, that would represent a much stronger level of evidence.

At present, NAD+ precursors have not established that final outcome.

Vivere takes an evidence-led approach to longevity, putting food and lifestyle first while viewing supplements as a considered addition rather than a replacement for healthy habits.

The aim should be to build a sustainable foundation around nutrition, movement, sleep and other established health behaviours. This approach also allows people to make more informed decisions about supplements without assuming that every new longevity product represents a breakthrough.

Vivere's approach to personalised health combines individual insights with nutrition and lifestyle guidance. More information about the philosophy behind the service can be found through the Vivere About Us page.

The hallmarks of ageing are interconnected biological processes that help researchers explain why cells and tissues change as we get older.

The original framework published in 2013 described nine hallmarks of ageing, while the updated 2023 framework expanded this to twelve hallmarks. These include genomic instability, mitochondrial dysfunction, epigenetic alterations and cellular senescence alongside other biological processes.

The hallmarks should not be considered independent causes. They interact with one another and can be influenced to varying degrees by genetics, environment and lifestyle.

Exercise, nutrition, smoking, alcohol intake and other behaviours can influence several processes associated with healthy ageing, which helps explain why lifestyle remains so important.

You cannot currently stop normal ageing, but you can influence factors associated with health and functional ageing.

Higher cardiorespiratory fitness is strongly associated with lower all-cause mortality, while a Mediterranean-style diet has demonstrated cardiovascular benefits. Not smoking, moderating alcohol intake and getting good-quality sleep are also important components of a healthy lifestyle.

These habits are particularly valuable because they can act on multiple ageing-related processes rather than targeting one biological pathway.

Both NMN and NR are NAD+ precursors, but their regulatory status and evidence base differ.

Human clinical trials have shown that NR can raise NAD+ levels and NR is authorised for sale as a novel food under specified conditions in Great Britain. NMN is not permitted for use in food supplements in the same way.

Anyone considering an NAD+ precursor should therefore check the regulatory status, ingredients, intended use and source of the product rather than assuming that all NAD+ supplements are equivalent.

NAD+ supplements and precursors can increase NAD+ levels, but there is currently no convincing evidence that they reverse human ageing.

Clinical trials have demonstrated biological effects including increases in NAD+ availability, with some studies reporting modest effects on cardiovascular measures. Other studies have found little or no significant improvement in metabolic outcomes.

For this reason, NAD+ products are better viewed as an optional extra rather than a proven anti-ageing treatment.

A diet for healthy ageing should provide a broad range of nutrients from varied foods while supporting cardiovascular, metabolic and muscle health.

A varied plant-based diet can provide fibre, vitamins, minerals and plant compounds. Vegetables, fruit, pulses and wholegrains can form the foundation of meals, while foods such as fish and olive oil can contribute beneficial fats.

Adequate protein is also important, particularly as maintaining muscle becomes increasingly important with age. Suitable sources include fish, poultry, eggs, pulses, dairy products and other protein-rich foods according to individual dietary preferences and requirements.

B vitamins also contribute to normal physiological processes. Niacin, also known as vitamin B3, is involved in normal energy-yielding metabolism and contributes to normal functioning of the nervous system [18].

A food-first approach can help provide these nutrients as part of a balanced diet without relying on individual supplements to compensate for an otherwise limited eating pattern.

“The science of ageing is complex, but that complexity should not make healthy ageing feel unnecessarily complicated. The hallmarks of ageing give us a valuable framework for understanding processes such as DNA damage, mitochondrial decline, epigenetic drift and the accumulation of senescent cells, while also showing how closely these processes are connected. 

From a practical perspective, the strongest message is that everyday habits can act on many of these processes at once. Exercise and cardiorespiratory fitness support physical function and metabolic health, while a varied plant-based diet, adequate protein, good sleep, not smoking and moderate drinking provide a strong foundation for long-term health. 

Our understanding of natural NAD+ maintenance is also developing, with research suggesting that exercise can influence NAD+ recycling pathways. NAD+ precursors such as nicotinamide riboside are scientifically interesting and can raise NAD+ levels, but the current human evidence remains modest and does not demonstrate life extension or reversal of ageing. They may therefore be considered by some people as an additional option, but they should not replace the free longevity tools that are already available to us every day. 

Being a discerning consumer means looking beyond exciting claims, understanding the strength of the evidence and keeping the basics at the centre of any approach to healthy ageing.”

Vivere helps you take control of your health with personalised insights from state-of-the-art gut microbiome testing, nutritional guidance, science-backed supplements, Liposomal NAD capsules, NAD injections and expert support. Sign up today and start living better, for longer.  

[1] The original 2013 hallmarks paper

[2] The 2023 hallmarks of ageing framework

[3] A large study linking cardiorespiratory fitness to longer life

[4] A 750,000-person analysis of fitness and mortality

[5] NHS physical activity guidelines

[6] The PREDIMED Mediterranean diet trial

[7] NHS stop smoking support

[8] The UK Chief Medical Officers' drinking guidelines

[9] The CALERIE calorie-restriction trial in humans

[10] A major review of NAD+ metabolism in ageing

[11] The FSA novel food register

[12] MHRA guidance on unlicensed "specials" medicines

[13] The largest randomised trial of nicotinamide riboside

[14] A randomised NR trial reporting modest cardiovascular effects

[15] An NR trial that found no major metabolic benefit

[16] A human study linking exercise, NAD+ and muscle function

[17] Research showing exercise raises the NAD+ salvage enzyme NAMPT

[18] NHS guidance on B vitamins including niacin