What are the Signs and Symptoms of NAD+ Deficiency to look out for?

Nicotinamide adenine dinucleotide (NAD+) has become an increasingly popular topic in discussions about healthy ageing, energy production and cellular health. Many people are now asking whether low NAD+ levels could explain symptoms such as tiredness, reduced concentration or slower recovery. 

In this article, Vivere's Head of Nutrition, Yusra Serdaroglu Aydin, a dietitian with a background in nutrition, food engineering and culinary arts, shares evidence-informed insights into what NAD+ is, whether NAD+ deficiency is recognised as a medical condition and the practical ways you can support healthy NAD+ levels. Her approach is grounded in science and shaped by a strong understanding of personalised nutrition and the human microbiome.

There is currently no recognised medical condition called NAD+ deficiency in healthy adults, but NAD+ levels naturally decline with age and can be supported through healthy lifestyle habits.

• Is NAD+ deficiency a recognised medical diagnosis? 

No, there is currently no recognised medical condition called NAD+ deficiency in otherwise healthy adults.

• Does NAD+ deficiency cause symptoms? 

Many symptoms people associate with low NAD+ are non-specific and may have a wide range of possible causes.

• How do you support healthy NAD+ levels? 

Healthy NAD+ levels are best supported through regular exercise, quality sleep, a balanced diet, avoiding smoking and limiting alcohol.

• Can you test NAD+ levels at home? 

Yes, some companies offer finger-prick tests to measure NAD+ levels. The sample is collected at home and then sent to a laboratory for analysis. Other tests assess NAD+ levels using a blood draw carried out at a clinic. 

• Can you self-diagnose low NAD+ levels? 

If you experience persistent fatigue or other unexplained symptoms, you should speak to your GP rather than self-diagnosing low NAD+.

No, NAD+ deficiency is not currently recognised as a standalone medical condition in healthy adults.

NAD+ is an essential coenzyme found inside every living cell where it helps convert nutrients into usable energy and supports hundreds of biological processes. Because of its important role in metabolism and cellular function, it has attracted significant scientific interest over recent years.

However, despite growing public awareness, there is no established diagnosis known as "NAD+ deficiency" for healthy people. Researchers recognise that NAD+ levels can vary between individuals and naturally decline as we age, but this is different from having a defined deficiency disorder.

Confusion often arises because people experience symptoms such as tiredness, poor concentration or reduced stamina and wonder whether NAD+ is responsible. These symptoms are extremely common and may instead relate to factors such as poor sleep, stress, nutritional deficiencies, illness, medication, hormonal changes or mental health conditions.

Rather than assuming NAD+ is the cause, it is important to consider your overall health and seek appropriate medical advice if symptoms continue.

People commonly associate low NAD+ with tiredness, brain fog, slower recovery and reduced physical performance, although these symptoms are not ospecific to NAD+.

Interest in NAD+ has grown alongside research into healthy ageing, leading many people to wonder whether everyday symptoms reflect declining cellular energy. Commonly discussed symptoms include:

• Persistent tiredness

• Reduced energy levels

• Difficulty concentrating

• Brain fog

• Lower exercise performance

• Slower recovery after physical activity

• Reduced resilience during periods of stress

• Feeling less mentally sharp than usual

Although these symptoms can affect quality of life, none of them confirms that your NAD+ levels are low.

For example, chronic fatigue may result from inadequate sleep, iron deficiency, vitamin deficiencies, thyroid disorders or other medical conditions [1] [2] [3]. Brain fog can occur during periods of stress, poor sleep or illness. Likewise, reduced physical performance may simply reflect reduced activity levels or ageing itself.

Because these symptoms overlap with many other conditions, they should always be considered within the wider context of your health rather than being attributed to NAD+ alone.

There is currently no widely accepted at-home test that can accurately diagnose low NAD+ levels.

Some private laboratories offer specialised NAD+ testing using blood samples, but these tests are not routinely used within standard healthcare. Researchers are still working to understand what constitutes healthy NAD+ levels across different ages and populations.

Even if a laboratory reports an NAD+ measurement, interpreting the result is not always straightforward. NAD+ exists inside cells throughout the body, and a single blood measurement may not fully reflect what is happening within individual tissues.

For most people, testing is unlikely to provide clear answers about symptoms such as tiredness or poor concentration.

If you have ongoing health concerns, your GP may recommend investigations that are more likely to identify common and treatable causes, including blood tests for iron, vitamin B12, folate, thyroid function or vitamin D where clinically appropriate.

The most effective way to support healthy NAD+ levels is by maintaining healthy lifestyle habits that benefit your whole body.

NAD+ is closely linked to cellular metabolism, meaning that many of the habits known to support long-term health also help maintain the biological systems that rely on this important coenzyme.

Rather than focusing on a single nutrient or supplement, consider the bigger picture by:

• Eating a varied, balanced diet.

• Remaining physically active throughout the week.

• Getting enough high-quality sleep.

• Managing stress where possible.

• Avoiding smoking.

• Limiting alcohol consumption.

• Maintaining a healthy body weight.

• Managing existing medical conditions with appropriate healthcare support.

These habits support overall metabolic health, which is far more important than chasing a specific biomarker in isolation.

NAD+ is a naturally occurring coenzyme that plays a vital role in energy production and cellular repair, and research suggests that its levels gradually decline as we get older.

Every cell in your body relies on NAD+ to help convert carbohydrates, fats and proteins into usable energy. It also supports enzymes involved in DNA repair, mitochondrial function and normal cellular communication.

Scientists believe that several factors contribute to lower NAD+ availability during ageing, including increased demand for DNA repair, changes in metabolism and alterations in enzyme activity. While this decline has attracted significant research interest, it is considered part of the normal ageing process rather than evidence of disease.

This is important because many headlines imply that everyone develops an NAD+ deficiency as they age. In reality, ageing is a complex biological process involving genetics, lifestyle, nutrition, physical activity, sleep and environmental influences.

 A major review of NAD+ metabolism in ageing shows that NAD+ is central to energy metabolism and DNA repair, and is consumed by sirtuins and PARPs, with levels changing during ageing [4]. Similarly, research measuring NAD+ decline in human tissue with age found that NAD+ levels declined with age in human tissue samples, alongside changes in oxidative stress markers [5]. However, across seven human cohorts using a validated method, a 2026 study of blood NAD+ across age and lifestyle found that whole-blood NAD+ stayed remarkably stable across age and lifestyle, so it is not a reliable ageing biomarker [6]. 

 Although maintaining healthy NAD+ levels may support normal cellular function, healthy ageing also depends on looking after your cardiovascular health, muscle mass, metabolic health, gut microbiome and overall nutritional status. NAD+ was among the metabolites most reduced in older adults' muscle, and exercise-trained older adults had higher muscle NAD+ in a human study linking NAD+, ageing and muscle function [7]. 

“The key takeaway is that your body makes NAD+ from everyday nutrients and continually recycles it. Rather than focusing on a single test result, it is more useful to support your overall health through good nutrition, regular physical activity, quality sleep and other healthy lifestyle habits. This whole-person approach is exactly what we recommend at Vivere.”

Symptoms such as low energy, reduced concentration and slower recovery are often linked online with low NAD+, but they should not be used to self-diagnose a problem with your NAD+ levels.

NAD+ plays an important role in cellular energy production, which is why researchers are interested in how changes in NAD+ metabolism may affect health as we age. However, experiencing fatigue or reduced performance does not automatically mean your NAD+ levels are low. In fact, ongoing tiredness is a very common reason to see a GP and has many identifiable causes worth checking, according to NHS guidance [8].

Many common lifestyle and health factors can contribute to similar symptoms. These include:

• Poor sleep quality or insufficient sleep.

• High levels of ongoing stress.

• A diet lacking essential nutrients.

• Reduced physical activity.

• Dehydration.

• Excessive alcohol intake.

• Smoking.

• Underlying health conditions.

For example, someone experiencing regular tiredness may assume they need an NAD+ boost when the cause could instead be iron deficiency, vitamin B12 deficiency, thyroid problems or another issue that requires medical assessment.

A personalised approach is important because every person has different nutritional needs, lifestyle habits and health factors. Looking at the complete picture, including diet, exercise, sleep, stress and medical history, is usually more valuable than focusing on one biological marker.

NAD+ research is promising, but it remains an area of scientific investigation. Supporting healthy NAD+ levels should form part of a wider approach to wellbeing rather than replacing proven healthcare advice.

You should speak to your GP if you experience persistent, unexplained symptoms rather than assuming they are caused by low NAD+.

Occasional tiredness is common and can happen after periods of stress, poor sleep or increased physical demands. However, ongoing symptoms that affect your daily life should be assessed by a healthcare professional.

Speak to your GP if you experience:

• Fatigue that does not improve with rest.

• Unexplained weight changes.

• Ongoing changes in mood.

• Persistent problems with concentration.

• Changes in appetite.

• Shortness of breath.

• Unusual weakness.

• Symptoms that are getting worse over time.

Your GP can discuss your symptoms, review your medical history and recommend appropriate testing if needed.

Healthcare professionals can help identify common causes of symptoms and provide personalised advice. This may include lifestyle recommendations, dietary changes or further medical support depending on your individual circumstances.

NAD+ supplements or treatments should not be used as a replacement for investigating possible underlying health concerns.

A true vitamin B3 deficiency is different from low NAD+ levels and is a recognised nutritional deficiency that can cause specific health problems.

Vitamin B3, also known as niacin, is one of the nutrients your body can use to produce NAD+. Severe niacin deficiency can lead to a condition called pellagra, which is uncommon in countries such as the UK where nutritional intake is generally sufficient. According to the MSD Manuals entry on niacin deficiency, Pellagra is rare where diets are varied and foods are fortified, and appears mainly in specific at-risk groups [9].

Pellagra is traditionally associated with three main symptoms known as the "three Ds":

• Dermatitis, particularly skin inflammation.

• Diarrhoea.

• Dementia, including confusion and cognitive changes.

This is supported by a clinical overview of niacin deficiency that found Pellagra results from severe niacin deficiency and presents with dermatitis, diarrhoea and dementia, with defined risk factors [10].

Severe deficiency may also cause additional symptoms such as weakness, loss of appetite and digestive problems.

Vitamin B3 deficiency is more likely to occur due to specific circumstances, including certain medical conditions, alcohol misuse, poor nutritional intake or problems affecting nutrient absorption.

This is very different from the gradual changes in NAD+ levels that occur naturally with ageing. A person can have normal vitamin B3 intake while still experiencing changes in NAD+ metabolism over time.

If you are concerned about nutritional deficiencies, a healthcare professional can help assess your diet, symptoms and overall health.

At-home NAD+ testing is not currently considered a standard way to assess your health or diagnose NAD+ deficiency.

While NAD+ testing methods exist in research settings and some specialist services, there is currently no commonly used home test that can tell you whether your NAD+ levels are "too low" or explain symptoms such as fatigue [6].

NAD+ is found inside cells throughout the body, making measurement and interpretation complex. A single measurement may not provide a complete picture of how your cells are functioning.

It is also important to remember that a biological marker does not always directly translate into a health outcome. A lower measurement does not necessarily mean someone is unhealthy, just as a higher measurement does not guarantee better health.

Instead of focusing only on NAD+ levels, supporting the processes that influence NAD+ production and use can be a more practical approach. This includes maintaining a healthy lifestyle, eating nutrient-rich foods and staying physically active.

Scientific understanding of NAD+ continues to develop, and future research may help establish clearer ways to assess NAD+ status and its relationship with health outcomes.

“I believe the best long-term approach is to focus on the everyday basics. Our bodies produce NAD+ using vitamin B3 and the amino acid tryptophan, so good nutrition plays an important role in supporting healthy NAD+ production.”

Healthy NAD+ levels are supported by habits that encourage good metabolic health, energy production and overall wellbeing.

Your body naturally produces NAD+ using nutrients from your diet, including vitamin B3. Lifestyle factors can also influence the biological pathways involved in NAD+ metabolism.

"Beyond food, the lifestyle factors matter just as much. Regular exercise is one of the most reliable ways to support your NAD+ system, because it stimulates the pathways that make and recycle it." 

Alongside that, she suggests these evidence-friendly habits.

Regular physical activity supports healthy metabolism and encourages the efficient use of energy within your cells.

Exercise places natural demands on your muscles, helping your body adapt and maintain important cellular processes. Both aerobic activities, such as walking, cycling or swimming, and resistance exercises, such as strength training, can contribute to overall health.

You do not need to complete intense workouts every day. Consistent movement that fits into your lifestyle can provide meaningful benefits.

Quality sleep supports many essential processes involved in physical and mental health, including cellular repair and energy regulation.

During sleep, your body carries out important maintenance processes that help you recover from daily demands. Poor sleep quality or insufficient sleep can affect mood, concentration, appetite regulation and energy levels.

Creating a consistent sleep routine, limiting screen use before bed and maintaining a comfortable sleep environment can help support better rest.

Reducing alcohol intake can support metabolic health and help your body maintain normal cellular processes.

Excessive alcohol consumption can affect nutrient absorption, increase oxidative stress and place additional demands on the body. Following recommended alcohol guidelines can help protect your overall health.

A balanced diet provides the nutrients your body needs to support NAD+ production and normal cellular function. Niacin (B3) supports normal energy metabolism and is found in a range of everyday foods according to NHS guidance [11].

 Foods containing vitamin B3 include:

• Poultry.

• Fish.

• Eggs.

• Nuts.

• Seeds.

• Whole grains.

• Legumes.

Plant-rich diets also provide antioxidants, fibre and a wide range of nutrients that support gut health and overall wellbeing.

A healthy gut microbiome is an important part of personalised nutrition because the bacteria living in your digestive system interact with the food you eat and influence many aspects of health. Vivere’s gut test can help you to get an accurate understanding of your gut microbiome health.

Avoiding smoking and protecting your skin from excessive sun exposure can help reduce factors associated with cellular stress.

Smoking introduces substances that can increase oxidative stress within the body, while excessive ultraviolet exposure can contribute to DNA damage in skin cells.

Simple protective habits, such as not smoking and using appropriate sun protection, form part of a wider approach to supporting long-term health.

NAD+ supplements and injections are becoming increasingly popular as people look for ways to support healthy ageing and cellular function, but they should be viewed as part of a wider health approach.

NAD+ supplements are designed to provide nutrients or compounds that may support the body's natural NAD+ pathways. Some products contain NAD+ itself, while others contain NAD+ precursors such as nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN), which the body can use as building blocks in NAD+ production.

Research into NAD+ supplementation is ongoing, with scientists investigating how different approaches may influence NAD+ levels and biological processes linked to ageing, metabolism and cellular health.

It is important to understand that supplements are not a replacement for the foundations of good health. A nutrient-rich diet, regular exercise, quality sleep and healthy lifestyle choices remain essential for supporting the body’s natural processes.

Before starting any supplement, it is advisable to consider your individual circumstances, including your diet, health goals and any existing medical conditions. A healthcare professional can help you decide whether a supplement is suitable for you.

Injectable NAD+ is another approach that has gained attention among people interested in cellular health and wellbeing.

NAD+ injections, such as those provided by Vivere, are designed to deliver NAD+ directly into the body. Research is still developing around their long-term benefits, effectiveness and the best ways to use them.

Injectable products must be used responsibly. They should only be considered with suitable guidance, particularly because injections require careful handling, correct administration and attention to safety standards.

Supporting healthy ageing is not about relying on one solution. The most effective approach combines evidence-informed lifestyle choices with personalised insights that consider your individual needs.

There is currently no widely accepted at-home test that can diagnose NAD+ deficiency.

Although specialist testing methods are available, there is no established home test that can reliably determine whether your NAD+ levels are responsible for symptoms such as tiredness or reduced concentration.

If you are experiencing ongoing symptoms, speaking with a healthcare professional is the best way to identify possible causes and receive appropriate guidance.

NAD+ levels naturally change over time, with ageing being one of the main factors associated with reduced NAD+ availability.

Other factors that may influence NAD+ metabolism include lifestyle habits, nutritional intake, physical activity levels and cellular stress. However, changes in NAD+ levels are part of a complex biological process and do not automatically indicate a health problem.

Supporting healthy habits, including regular movement, balanced nutrition and good sleep, can help maintain overall cellular health.

There is no medically recognised treatment for "fixing" low NAD+ levels in healthy people.

The most reliable way to support your body's natural NAD+ pathways is through healthy lifestyle habits, including eating a varied diet, exercising regularly, sleeping well and avoiding factors that can negatively affect health.

Some people choose to explore NAD+ supplements or injections, but these should be considered carefully and as part of a wider personalised health strategy. Vivere provides the highest standard of NAD+ injection available.

Constant tiredness is not necessarily a sign that you need an NAD+ boost and may have many other possible causes.

Persistent fatigue can be linked to factors such as poor sleep, stress, nutritional deficiencies, medical conditions or lifestyle changes. If tiredness continues or affects your daily activities, it is important to speak with your GP.

Understanding the reason behind fatigue is more valuable than simply trying to increase one biological compound.

No, the idea that everyone's NAD+ levels fall by exactly 50% by age 40 is an oversimplification.

Research suggests that NAD+ levels may decline with age, but the rate of change can vary significantly between individuals. Factors including genetics, lifestyle, nutrition, physical activity and overall health can influence how NAD+ metabolism changes over time.

Ageing is a complex process involving many biological systems, and NAD+ is only one part of the wider picture.

“NAD+ is an important molecule involved in energy production and cellular processes, and research into its role in healthy ageing continues to grow. While people may associate low NAD+ with symptoms such as tiredness, reduced focus or slower recovery, these signs are not specific enough to confirm an NAD+ problem. Supporting your health through balanced nutrition, regular movement, quality sleep and positive lifestyle choices remains the most effective foundation for maintaining healthy cellular function. Personalised approaches that consider your unique nutritional needs, lifestyle and health goals can help you make informed decisions about your wellbeing.”

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

The information in this article is supported by the following sources.

1. NHS. Iron deficiency anaemia. nhs.uk/conditions/iron-deficiency-anaemia

2. NHS. Vitamin B12 or folate deficiency anaemia. nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia

3. NHS. Underactive thyroid (hypothyroidism). nhs.uk/conditions/underactive-thyroid-hypothyroidism

4. Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology. 2021;22(2):119-141. nature.com/articles/s41580-020-00313-x

5. Massudi H, Grant R, Braidy N, Guest J, Farnsworth B, Guillemin GJ. Age-associated changes in oxidative stress and NAD+ metabolism in human tissue. PLoS ONE. 2012;7(7):e42357. journals.plos.org/plosone/article?id=10.1371/journal.pone.0042357

6. Tretowicz MM, Scantlebery AML, Schomakers BV, et al. Human whole-blood NAD+ levels do not vary with age or lifestyle interventions. Nature Metabolism. 2026;8:1282-1290. nature.com/articles/s42255-026-01537-5

7. Janssens GE, et al. Healthy aging and muscle function are positively associated with NAD+ abundance in humans. Nature Aging. 2022;2:254-263. nature.com/articles/s43587-022-00174-3

8. NHS. Self-help tips to fight tiredness. nhs.uk/live-well/sleep-and-tiredness/self-help-tips-to-fight-fatigue

9. MSD Manual Professional Version. Niacin Deficiency. msdmanuals.com (Niacin Deficiency)

10. Niacin Deficiency. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. ncbi.nlm.nih.gov/books/NBK557728

11. NHS. B vitamins and folic acid. nhs.uk/conditions/vitamins-and-minerals/vitamin-b

12. Food Standards Agency. Regulated products register: nicotinamide riboside, authorised novel food (novel-96). data.food.gov.uk/regulated-products/novel_authorisations/novel-96

13. Medicines and Healthcare products Regulatory Agency. The supply of unlicensed medicinal products ("specials"). GOV.UK. gov.uk/government/publications/supply-unlicensed-medicinal-products-specials

14. Vinten KT, Trętowicz MM, Coskun E, van Weeghel M, Cantó C, Zapata-Pérez R, Janssens GE, Houtkooper RH. NAD+ precursor supplementation in human ageing: clinical evidence and challenges. Nature Metabolism. 2025;7(10):1974-1990. nature.com/articles/s42255-025-01387-7

15. Food Standards Agency. Register of regulated product applications: beta-nicotinamide mononucleotide as a novel food ingredient (RP-2116). data.food.gov.uk/regulated-product-applications/products-list/RP-2116