DunedinPACE
DunedinPACE is a blood test that reads chemical marks on your DNA to estimate how fast you are ageing, and it is sold direct to consumers as a biological-age score. In studies it predicts disease and death across groups of people, but one person's reading shifts from day to day, so it can't yet guide individual decisions.
Treat it as optional, and never change treatment on the result alone. If you test anyway, use a provider that names its published clock and runs it in an accredited lab, and keep the provider, sample type, time of day and fasting state the same every time.
What it is
DNA-methylation clocks read chemical tags on DNA that shift with age and try to measure ageing itself: the rate at which a person's biology is drifting from their age in years. Three generations now exist, with sharply different uses:
| Generation | Examples | Trained on | What it is good for |
|---|---|---|---|
| First | Horvath, Hannum | Age in years | Little beyond estimating your age |
| Second | GrimAge, PhenoAge | Mortality and clinical blood markers | Predicting death and disease in groups |
| Third | DunedinPACE | The rate of organ-system decline within one birth cohort | Tracking the pace of change in research trials |
DunedinPACE was built on a long-running study of New Zealanders all born in 1972–1973, the Dunedin study, by tracking 19 organ-system markers at four timepoints over two decades.[1] Because everyone in it was born within the same year, it sidesteps the generational differences that muddle clocks built across age groups, such as leaded petrol, vaccination history and diet.
The output is a single number. A score of 1.0 means one biological year per calendar year; below 1.0 means slower ageing (0.85 is 15% slower than the calendar); above 1.0 means faster. In its development paper, DunedinPACE's links with disease and death were similar in size to GrimAge's.[2]
Precise in the lab, unstable in you
DunedinPACE gives nearly the same number when the same blood sample is run twice: an intraclass correlation (a reliability score where 1.0 is perfect agreement) of 0.96 across 36 repeat runs.[3] That is lab precision, not stability in the person.
- It moves within hours or days. When the same people were re-sampled around meals, acute stress, air-pollution exposure or a change of altitude, most clocks were only low-to-moderately stable, and DunedinPACE was among the less stable ones.[4]
- Year-to-year changes tend to reverse. In 899 generally healthy older adults (average age 70) tested yearly, DunedinPACE did not change on average over two years, and across the clocks studied, one-year rises tended to reverse the next year.[5]
- No accuracy standard exists. There is no agreed standard yet for when a clock is accurate enough to guide one person's care.[6]
So a change between two personal results a year apart can easily be noise. Clocks can detect average effects across a trial group, but none is validated for tracking one person, and testing more often only samples more noise.
What has moved it in trials
A slower clock predicts, but doesn't prove, a longer or healthier life: these are surrogate markers, not hard outcomes. Only a few randomised trials have shown a clock slowing, all as secondary analyses with small effects.
- Omega-3. In a trial in adults over 70, 1 g of omega-3 a day slowed three clocks, by about 1% on DunedinPACE. Vitamin D and exercise on their own moved none, and the three combined added up on only one clock (PhenoAge).[7]
- Calorie restriction. Two years of calorie restriction, in which people achieved about half the prescribed 25% cut, slowed DunedinPACE by 2–3% but did not move PhenoAge or GrimAge.[8]
- Semaglutide. The GLP-1 drug slowed DunedinPACE by about 9% over 32 weeks in a small trial in 84 people with HIV-associated fat gain.[9]
The wider science of the clocks is on Epigenetic alterations.
Buying a test
The commercial clock-testing market is uneven on analytical quality. Before paying, ask the provider which published clock algorithm it reports, whether the assay runs in an accredited clinical laboratory, and what its test-retest reliability is on repeat samples from the same person.
Then keep every repeat test with the same provider and the same sample type. Absolute scores are not comparable across platforms: in some clocks, the same person's estimate differed by almost 30 years between a cheek-swab or saliva sample and blood.[10] A change of vendor or sample destroys the only thing the test was for.
What to do
- Don't treat it as part of a health check. It is a research measure; the midlife lab panel covers the tests that change decisions.
- If you test, standardise everything: the same provider, sample type, time of day and fasting state.
- Don't retest often. More frequent results mostly sample day-to-day noise.
- Don't change treatment on the result alone.
Further reading
- Belsky DW et al. DunedinPACE, a DNA methylation biomarker of the pace of aging. eLife 2022.[11]
- Sehgal R et al. Biological Versus Technical Reliability of Epigenetic Clocks and Implications for Disease Prognosis and Intervention Response. Aging Cell 2026.[12]
- Hamaya R et al. Longitudinal changes in epigenetic measures over 2 years: methodological implications. Geroscience 2026.[13]
- Bischoff-Ferrari HA et al. 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. Nat Aging 2025.[14]
- Apsley AT et al. Cross-tissue comparison of epigenetic aging clocks in humans. Aging Cell 2025.[15]