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01. How to Lower Your Biological Age? What Epigenetic Tests and Scientific Studies Reveal
Biological age: what can it tell us, and what can it not?
Imagine you are 50, but a test puts your biological age at 43. Is that good news? Perhaps — but first we need to know what the test measured, how accurate it is and what its result means.
The question “how to lower your biological age” is a recurring topic in biohacking and longevity. The scientific answer is more complex than a list of substances or habits. A change in a score, a slower pace of ageing and a longer life are three different outcomes.
Longevity: more years of health, strength and independence
What is biological age? It is an estimate of the age that the condition of your body corresponds to, based on selected measurements. Your age in years is counted from birth. Biological age can be estimated from blood results, measures of physical abilities or chemical marks on DNA. Two people of the same chronological age may therefore have different estimated biological ages. The result depends on the method used, because different tests capture different aspects of ageing. [1] [3]
The goal is to retain mobility, memory, physical capacity and independence for as long as possible. What matters is how a person actually functions and how their health develops over time.
The starting point is everyday habits: regular walking and strength training suited to your health, a varied diet with an appropriate energy intake, enough protein and fibre, good sleep and not smoking. Looking after vascular and metabolic health also matters — monitoring blood pressure, blood glucose and blood lipids, and addressing abnormalities with a doctor in good time. You can start without a biological age test.
CALERIE and DO-HEALTH show that some markers of biological ageing can be influenced. Later in this article, we explain exactly what changed and what these findings mean. [1] [2]
Chronological age, biological age and the pace of ageing
Chronological age is the number of years since birth. Biological age is an estimate from a particular test. The test may assess blood results, physical abilities or changes within cells. Different tests can therefore give different biological ages. [1]
| Measure | What question does it answer? |
|---|---|
| Chronological age | How much time has passed since birth? |
| Estimated biological age | What age do the measurements correspond to according to this test? |
| Pace of ageing | How quickly are age-related changes occurring according to this test? |
Imagine a car journey: biological age is roughly like how far you have already travelled. The pace of ageing is like your driving speed. Driving more slowly does not mean travelling backwards. In the same way, slower ageing does not, on its own, mean becoming younger.
How do scientists estimate age from DNA?
DNA carries tiny chemical marks. Their patterns change throughout life. Scientists use calculations to analyse these changes and estimate biological age or the speed of ageing. These methods are called epigenetic clocks. They are not clocks counting down how much life we have left. [3]
This is different from a standard genetic test. Genetic testing examines the DNA sequence itself, for example particular inherited differences. Epigenetic testing examines chemical marks on DNA. Knowing whether a sample comes from blood or saliva does not, by itself, tell us what a test can reveal.
Why can two tests show different ages?
Each test may use different calculations and examine different marks. The sample, laboratory work and natural changes in the body also affect the result. One test can therefore give a different estimate from another.
A small difference between two results does not necessarily mean that ageing has sped up or slowed down. A method that is useful for studying large groups may not be accurate enough to guide decisions about one person's health. [3]
Can ageing be influenced? What two studies found
Scientists are already studying whether changes in diet or exercise also change measures of ageing. The findings are interesting. However, we need to distinguish between a better test result and actually living longer.
CALERIE: a small slowdown according to one method
In a two-year trial, scientists studied a reduction in calorie intake while maintaining essential nutrients. The original trial enrolled 220 adults without obesity. They were randomly assigned either to reduce their calorie intake or to continue their usual eating habits.
In a later analysis, published in 2023, researchers assessed collected samples using three methods. One estimated how quickly the body was ageing. The other two estimated biological age.
The method measuring the speed of ageing showed a small slowdown in the calorie-restriction group. The other two methods did not show a significant change. [1]
What does this mean? A change in diet influenced one measure of ageing. This does not yet prove that participants became younger or will live longer. Further follow-up is needed to establish effects on disease and lifespan. The result is not a recommendation to starve yourself or severely restrict food.
For curious readers: what are these methods called?
DunedinPACE estimates the pace of ageing – how quickly age-related changes are occurring. PhenoAge and GrimAge provide estimates of biological age that also relate to health risks. Each method assesses a slightly different aspect of ageing, so their results can differ. [1]
DO-HEALTH: small changes after three years
An analysis published in 2025 examined 777 older participants. Scientists studied vitamin D, omega-3 and a simple home exercise programme, separately and together.
Omega-3 supplementation was associated with small favourable changes in three of the four methods used to measure ageing. When vitamin D, omega-3 and exercise were combined, their benefits added together in one method. [2]
For selected results, the difference amounted to roughly three to four months over the three-year follow-up. This is a difference in estimated biological age, not proof that people gained extra months of life. Results in this group also do not guarantee the same effect for everyone.
For curious readers: what exactly do these numbers mean?
The authors reported a difference of 2.9–3.8 months over three years for selected estimates. The greater combined effect of all three approaches was seen with PhenoAge. This was a later analysis of samples from a selected group of participants in the original trial. [2]
| Finding | What it does not establish |
|---|---|
| One measured indicator improved. | The entire body has demonstrably become younger. |
| A group achieved a more favourable average result. | Every participant benefited equally. |
| Only some methods showed an improvement. | All measurement methods will show the same change. |
| A study lasted two or three years. | An effect on total lifespan has been confirmed. |
Light and ageing: what are scientists studying?
Photobiomodulation (PBM for short) uses light of specific wavelengths to influence biological processes. Scientists are also studying whether it could help preserve certain abilities in older age.
In a study involving 55 healthy older adults, researchers applied light to the outside of the head. They observed an improvement in a more demanding working-memory task. Working memory is the ability to briefly hold information and work with it, for example when doing mental arithmetic. [4]
Another study involved people over 50 with mild difficulties in memory and other thinking abilities. The group receiving the real light application improved more on a test than the group receiving a simulated application. Blood levels of a protein called BDNF also increased. This protein is involved in the ability of nerve cells to adapt and change their connections. [5]
In an experiment on mice with accelerated heart ageing, light reduced some harmful changes in the heart and blood vessels. More of the mice that received light survived during follow-up. This result concerns mice, not people. [6]
What do we know, and what remains uncertain? The findings give scientists reasons to continue studying this approach. They do not yet show that light reduces biological age or extends human life. Results depend on the specific way light is applied. The studied application through the head cannot automatically be equated with use inside the nose, blood irradiation or another device.
Read more in article 03: Mitochondria and ageing.
What should you ask before buying a biological age test?
A number alone is not enough. Before paying for a test, find out what its result can tell you.
- What does the test measure? Does it estimate biological age or the speed of ageing?
- How has it been checked? Is there a study showing its accuracy and whether repeating it produces similar results?
- How far off could the result be? Could a difference of several years occur without any real change in health?
- Who is it suitable for? Has it been checked in people your age and using the same type of sample, such as blood or saliva?
- What does an improvement mean? Has a better number been shown to relate to better health?
- Who will explain the result? And how does the company protect the information obtained from your sample?
When a company sells both the programme and the test: a better result after completing the programme does not, on its own, prove rejuvenation. The number may change naturally or because of measurement differences. Independent checks matter.
What does this research mean for everyday life?
Biological age tests help scientists study ageing. In everyday life, what matters most is our ability to walk, think, work and manage daily activities. A better number on a test is not enough. Discuss health concerns and examination results with a doctor.
You can start with the everyday habits outlined in the introduction and monitor changes in fitness, strength and daily functioning. Later articles in the series explore exercise, nutrition, mitochondria and other areas of research. For each topic, we explain what scientists found and what it could mean for everyday life.
What do we still need to find out?
- Whether a better test result means fewer illnesses or more years in good health.
- Which methods are sufficiently accurate for monitoring an individual.
- How long changes persist and whether they can be replicated in other groups.
- What long-term benefits and risks the approaches under investigation may have.
Frequently asked questions
How can I find out my biological age?
Some tests assess blood results; others examine chemical marks on DNA. Each uses its own calculations. The result is an estimate, not the exact age of every organ. Before buying, find out what the test measures and how accurate it is.
If a test shows five years less, have I become younger?
The test has calculated a lower age. This alone does not mean that all your organs have become younger, that your risk of illness is lower or that you will live longer.
Does it make sense to compare results from two companies?
If the companies use different tests, their numbers may not be directly comparable. Differences can arise from the calculations or sample processing. Even with the same test, results can fluctuate a little.
Do these studies prove that I should start taking supplements?
No. The studies examined specific approaches in selected groups of people. Their findings do not guarantee the same effect for you and are not a personal recommendation to take supplements.
Is biological age the same as genetic susceptibility to disease?
No. These are different questions requiring different tests. An estimate of biological age does not replace targeted genetic testing or the diagnosis of disease.
Sources and research from around the world · 6 publications
- Waziry R. et al. 2023. Effect of long-term caloric restriction on DNA methylation measures of biological aging in healthy adults from the CALERIE trial. Nature Aging. Original research analysis. Read the study.
- Bischoff-Ferrari H. A. et al. 2025. Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation clocks of biological aging in older adults from the DO-HEALTH trial. Nature Aging. Original research analysis. Read the study.
- Apsley A. T. et al. 2025. From population science to the clinic? Limits of epigenetic clocks as personal biomarkers. Epigenomics. Expert perspective, not an intervention study. Read the publication record.
- Yang et al. 2025. Transcranial photobiomodulation improves functional brain networks and working memory in healthy older adults: An fNIRS study. Randomised, single-blind, sham-controlled crossover study in 55 healthy older adults. Read the publication record.
- de Oliveira et al. 2024. Transcranial photobiomodulation increases cognition and serum BDNF levels in adults over 50 years: A randomized, double-blind, placebo-controlled trial. Randomised, double-blind, placebo-controlled study in mild cognitive impairment; 93 participants enrolled and 76 completed the study. Read the publication record.
- Experimental study, 2023. Photobiomodulation therapy mitigates cardiovascular aging and improves survival. Research on cardiovascular ageing and survival in a mouse model, not evidence of extended human lifespan. Read the publication record.
Author’s note: The selected studies illustrate the topic; this is not a systematic review of the entire literature. This article is educational and does not replace individual medical advice. New findings will be added with an update date.
KINGRAY AcademyWith love for the body. With respect for science.
