Biological age tests, what they measure and how to use one well

What the test is

Your DNA carries chemical tags, called methyl groups, that change in predictable ways as you age. An epigenetic clock reads these tags at many sites and turns them into an estimate of age. One of the first widely used clocks was built from about 8,000 samples and uses 353 sites [1].

Later clocks were trained on health outcomes as well as birthdays. GrimAge was built to predict lifespan, and in large validation data it was strongly associated with time to death, heart disease and cancer [2]. DunedinPACE estimates the pace of ageing, trained on the decline of 19 measures of organ function over two decades in one birth cohort [3].

Why it is done and who it may suit

People use a biological age test to see a broad picture of how they are ageing, and to follow change after altering how they sleep, train or eat. DunedinPACE showed high test-retest reliability and was associated with illness, disability and death, which makes a pace measure a sensible choice for tracking [3].

A test may suit you if you are well, want a baseline to measure against, and would use the result as a prompt to act on what is known to matter, such as activity, sleep, weight and smoking.

Who it is not for

A biological age test does not diagnose any condition, and it does not replace screening or blood tests. If you have symptoms such as unexplained weight loss, chest pain, palpitations or breathlessness, see a doctor first, and in an emergency call 999 in the UK or the local emergency number elsewhere.

It may not suit you if a number above your real age would cause lasting worry, or if you want a single figure to decide on a treatment.

Benefits and limitations

The benefit is a broad summary that responds to change and can be repeated from a simple sample. Several clocks predict illness and death across large groups of people [2].

The limits matter for one person. Technical noise alone produced differences of up to 9 years between repeat measurements for six widely used clocks, and newer computational methods brought most repeats within 1.5 years [4]. Researchers also note the lack of agreed standards for validating ageing biomarkers before clinical use [5], and open questions about what the clocks measure [6].

Read a result as a trend across repeat tests from the same laboratory, and as one input beside measures with firmer evidence, such as blood pressure, cholesterol, blood sugar and fitness.

Risks

The sample is a finger prick, so the physical risk is small. The main risks are false reassurance from a young result, needless worry from an old one, and spending on products that a clock cannot show to work. Because results vary between methods, comparing numbers from different providers can mislead [4].

How you prepare and what to expect

No fasting or referral is needed. You collect a few drops of blood from a finger prick at home, which takes about 5 minutes, and return the card in a prepaid envelope. Results arrive in 2 to 3 weeks after the laboratory receives the sample.

Results and what happens next

Our report includes a biological age read from more than 900,000 methylation markers, a pace of ageing, and age estimates for 11 organ systems. Ask a doctor to read it beside your blood results and history. Where a number stands out, the next step is usually a test with stronger evidence, such as a lipid profile or HbA1c, before any change to treatment.

If you are tracking a change, repeat the test every 6 to 12 months, because methylation shifts slowly. These questions help you get the most from the result.

• Which of my results has the strongest evidence behind it?
• What would change your advice, and what would not?
• Which measures should we repeat, and when?
• Is anything here a reason for a test with firmer evidence?

How The Wellness can help

The epigenetic age test comes as a postal kit, with a self-collect option in London on Saturday afternoons. For a fuller picture, a free longevity consultation by video helps you decide which measures are worth taking, and the Longevity+ blood test adds markers such as ApoB and Lp(a) with a written plan.

Our GMC registered doctors see patients on Baker Street in Marylebone and Eccleston Street in Belgravia, every day of the week.