Biological age test: unlocking the secrets of longevity

Feb 5, 2024

Key takeaways

  • Biological age is a reflection of our health as we age. 

  • By testing our biological age we can better predict and prevent age-related health issues. 

  • Biological age can be determined by various tests such as: epigenetic clocks, telomere length measurement, biomarkers, and physical and mental functioning. 

  • Biological age is a complex and multifaceted concept. No single test can provide a perfectly accurate measurement, but AI algorithms can analyse various data points to help predict it.

  • Results from biological age tests can guide personalised health recommendations based on our unique biological, lifestyle and medical profile.

Why biological age matters

Results from biological age tests can guide personalised health recommendations based on our unique biological, lifestyle and medical profile.Anti-ageing practices have been around since time began. Even in ancient times, humans tried to unlock the secrets to longevity and how to increase healthspan. Only recently has it become possible to measure biological age. Although no single test can provide a perfectly accurate measurement, there have been significant advances in the precision of biological age testing. Individual tests can be combined to get a more accurate output that better predicts age-related health concerns. The results can be used to generate personalised health recommendations that help prevent disease and premature ageing. 

Quality of life 

Our goal should be to enhance our quality of life as we age. We can't control our chronological age, but biological age considerations can contribute to focused strategies that promote healthy ageing, allowing us to maintain physical and cognitive function, independence and overall well-being for longer. 

Further research 

Understanding biological ageing plays a crucial role in advancing longevity research. It helps scientists identify factors that contribute to the ageing process, potentially leading to the development of more impactful interventions to extend healthy lifespans. The more knowledge gained in the field of biological ageing, the better chance of developing successful therapies and recommendations. 

Methods of testing biological age 

Blood tests

Certain biomarkers in the blood are indicative of our rate of biological ageing. Levels of certain proteins, hormones and other substances, change with chronological age. They can tell us how well certain organs are functioning and what our disease risk is. It is important to retest the blood every six months in order to assess what is ‘normal’ for you and how any personal lifestyle changes or interventions are working. 

Saliva tests

Saliva tests help calculate biological age because they allow us to analyse DNA methylation - a process that changes the activity of the DNA and genomes. Measuring telomere length in saliva can also be used to assess cellular ageing because telomere (the protective caps at the ends of chromosomes) shortening is associated with increased biological age. 

Stool tests

Assessing digestive health and gut microbiome composition is a key component of measuring biological age and determining longevity. Increasing evidence suggests that gut microbiome changes play a strong role in age-related diseases (2).  

How to test your biological age 

Every testing provider generates your biological age calculation differently. 

Blood test

  • Schedule your blood test for the morning. 

  • Avoid strenuous exercise for 48 hours before your test. 

  • Refrain from alcohol, smoking and recreational drug use for 24 hours before your blood test. 

  • Fast for 12 hours before the blood collection, but stay hydrated by drinking water or herbal tea. 

  • Take a 12-hour break from your usual supplementation routine prior to your blood test. 

  • Continue taking prescribed medications. 

 Following these instructions will help produce more accurate test results. Food or drinks, other than water, can temporarily raise blood sugar, blood lipids and cholesterol. Drinking water helps prevent dehydration which can raise haematocrit, albumin and creatinine levels. Even supplements can interfere with the accuracy of tests. Biotin supplements, for example, interfere with immunoassays, which are just a number of biochemical tests that measure the concentration of certain markers in your blood (19).

Saliva test

A saliva- test kit requires taking a swab from the inside of your cheek or collecting a small amount of saliva in a tube. In order to achieve the most precise and reliable results:

  • Avoid putting things in your mouth: refrain from eating, drinking, smoking, chewing gum or brushing your teeth 30 minutes before your saliva test. 

  • Remove any lip makeup - wipe off your lipstick, lip balm or lip liner. 

  • If you usually have trouble producing saliva, gently massage your cheeks.

Stool test

Antibiotics, gastrointestinal infection may lower the diversity and balance of good versus harmful bacteria. It’s advisable to wait for two months before collecting a stool sample to allow your microbiome to stabilise if you have recently had or have taken: 

  • Gastrointestinal infection 

  • Abdominal surgery 

  • Antibiotics (excluding topical treatments like eye drops or skin cream) 

  • NSAIDs (excluding occasional use of over-the-counter painkillers) 

Types of biological age testing

Various tests for biological age have been developed, but there’s no one test that can predict healthspan and longevity. Currently, a combination of biological age tests, alongside data-based algorithms and medical expertise remain the best method of predicting biological age. 

Biomarkers and cellular age 

Blood biomarkers

Some tests use a combination of biomarkers to estimate biological age. These may include levels of certain proteins, inflammatory markers and nutrients in the blood that change as we age. For example, chronic inflammation is associated with ageing and age-related diseases (6). Tests that measure inflammatory markers like C-reactive protein (CRP) or interleukin-6 (IL-6) provide information about the molecular level amount of inflammation in our bodies.

Glycan age 

Glycans are sugar molecules found on the surface of cells. A glycan age test evaluates molecular changes in glycans to estimate the biological age of cells. It essentially looks at the state of your immune system and inflammation by assessing the level of chronic inflammation, which is directly influenced by lifestyle (19). 

Proteomics and metabolomics

Proteomics and metabolomics are advanced biological tests that analyse your cell proteins and metabolites, small molecules that are involved in various cellular processes, such as energy production, growth and maintenance of healthy cell structures (22).

Proteomics focuses on the set of proteins within a cell, tissue or organism. It provides insights into your cellular functions, pathways and interactions. Metabolomics examines small molecules, known as metabolites, to understand the metabolic processes, or chemical reactions that occur in your body. These tests are able to highlight underlying physiological conditions to better understand your current health status and biological age.

DNA related tests  

Epigenetic clock tests 

This type of test is based on analysing changes in DNA methylation patterns, which are modifications to DNA molecules that can affect how our genes express themselves. Some methylation markers are inherited, and some occur as a result of our lifestyle and environmental factors. As we age these markers accumulate, which confuses genetic instructions and affects cellular function. This contributes to cellular ageing and increases the risk of developing age-related diseases (3). Researchers have developed various epigenetic clocks, including Horvath's clock, Hannum's clock, DNA PhenoAge, and DNA GrimAge (4). 

Telomere length measurement

Telomeres are the protective caps at the ends of our chromosomes, or long DNA molecules, and they shorten as our cells divide. Shorter telomeres are associated with increased age, so if we test them, we can better predict biological age. Telomere length measurement can be done by a quantitative polymerase chain reaction (qPCR) test, which uses smaller amounts of DNA, and Southern blotting, which detects DNA molecules from a mixture (5). However, it should be noted that telomere lengths may differ among cell types, and further research is required to identify the specific cell types or combinations of multiple tests that yield the most precise measurement of biological age (21).

Physical assessment 

Photo-ageing clock

This is a non-invasive test which takes high resolution images of wrinkles and skin pigmentation to predict age. This can estimate skin ageing based on our exposure to sunlight or environmental damage. Some research has suggested this may estimate age with better accuracy than looking at DNA methylation (20). 

Physical and mental functioning

Decline in physical function - losing grip strength, a slower walking speed, or reduced balance, are common aspects of ageing. VO2 max, also known as maximal oxygen consumption, represents the highest quantity of oxygen we can use during intense physical activity. It’s a reliable measure of cardiovascular fitness and aerobic endurance, which can reflect your biological age. VO2 max needs to be performed on site in a research facility, because of the equipment required to perform the test.

Cognitive decline is another common aspect of ageing. Slower thinking or difficulty maintaining attention, recalling memories or multitasking are all examples of cognitive decline in aging. Cognitive functioning testing in ageing currently requires an assessment by a clinical psychologist. However, incorporating physical and mental function into an accurate biological age result poses challenges because of the equipment and expertise required.

Biological age tests and machine learning

Biological age test research remains dynamic and multidisciplinary. It requires the integration of various scientific approaches and biological tests in order to gain a comprehensive understanding of ageing and effective interventions to slow the process down. Statistical calculations and predictions, including machine learning algorithms, can analyse various data points which can fairly reliably predict biological age. 

Test your biological age with NU  

NU uses a combination of tests that are easy to use, and are available to anyone at a relatively affordable price point.

Blood biomarkers


Chronic inflammation is a characteristic of ageing which occurs with cellular senescence (cessation of cell division), and immunosenescence (the gradual decrease of immune function and inability to filter inflammatory markers) (7). This can create a negative cycle in the body, leading to disease and damaged organs. 

The prevalence of inflammatory markers have been shown to increase with age. This includes serum cytokine, serum TNF-R1, IL-6, CRP, and TNF-R1. When the levels of pro-inflammatory cytokines, or a signalling molecule that promotes inflammation, are higher than normal ranges, it can indicate certain diseases (7). 


High levels of total cholesterol and LDL cholesterol may increase the risk for heart disease and stroke in both men and women (9). Although age has an impact on cholesterol levels, it's not an independent predictor of change, meaning we have some control over balancing these levels with healthy lifestyle changes, including eating more seasonal fruits and vegetables (8). 

Stool test


In general, as we age our microbiome diversity decreases. Several studies have shown that when we have an imbalance of microbiomes, it can lead to changes in health, related to ageing. This includes decreased immune function and changes in body composition and increased risk for age-related disease such as heart disease or osteoporosis, or decreased bone strength (10). Our microbiome also communicates to our brains. Less microbiome diversity as we age, has been associated with poorer cognition, such as slower reaction times and less verbal fluency (11).  Decrease in microbiome diversity can also cause an increase in harmful pathogens.

Specific species also have an impact on health and biological age. Research has suggested that retaining Bacteroids in particular have predicted longer healthspan (12). Species that produce short chain-fatty acid (SCFA) are also linked to better health because they protect our gut and organs. (13). These SCFA are important for overall health because they protect our gut and organs. 

In summary

Biological age tests can identify signs of accelerated ageing or increased risk factors for age-related diseases before clinical symptoms appear. Early detection allows for proactive interventions and lifestyle modifications to address health issues before they become more serious.

Results from biological age tests can guide personalised health recommendations. This may encourage lifestyle choices that are healthier habits include targeted interventions such as specific dietary changes, exercise programs, or other lifestyle modifications based on our unique biological profile.

If you make lifestyle changes in response to NU’s biological age test results, you can use subsequent biological age tests to accurately track progress and monitor the effectiveness of these interventions. This feedback loop can help you to constantly adjust and fine tune healthy behaviours.

While biological age tests can offer valuable insights and motivate us to make positive lifestyle changes, they should be viewed as tools for assessment rather than definitive measures. Consulting with healthcare professionals and considering multiple indicators of health is crucial for a comprehensive understanding of our ageing process.


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