# The biological age test you can buy, and whether to buy one

Source: https://onco.cc/technologies/rejuv-measure-consumer-biological-age-tests/  
OnCo record `rejuv-measure-consumer-biological-age-tests` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

You can send saliva or blood to a company and be told your biological age. The underlying science is real and is described in the records on biological ageing after treatment; the test you can buy is not that science. Repeat measurements of the same sample can differ by years, no result changes any treatment, and nothing you can do in response has been shown to change what happens to you.

## Summary

This belongs on the measurement page rather than the frontier page because the question people actually ask is a measurement question: should I buy one, and what would I do with the answer.

The short answer, with the reasons.

The technical noise is larger than the effect people want to detect. Testing the reliability of six prominent epigenetic clocks, Higgins-Chen and colleagues found that "technical noise produces deviations up to 9 years between replicates for six prominent epigenetic clocks, limiting their utility". Their fix, computing principal components from CpG-level data before predicting age, brought most replicates within 1.5 years. A consumer result that does not state which version of which clock was used, and does not report a replicate, cannot be interpreted. If a person is told they are three years older than their calendar age, that is well inside the published replicate variation of the unimproved clocks.

The underlying measurement is unevenly reliable at the probe level. Sugden and colleagues correlated repeat measurements of the same DNA samples on the standard methylation arrays in 350 blood samples and found that "the reliability of each of these measurements is not equal, and little consideration is paid to consequences for research", with unreliable probes generating an unknown volume of false negatives. That is a problem for research and a larger one for a single consumer result with no replicate.

No result leads to an action with evidence behind it. No clock is a validated clinical test, none guides a treatment decision, and whether moving a clock changes any outcome has never been tested. That is stated on the biological ageing record elsewhere on this front and applies with more force to a consumer product, which is typically not even the same clock as the one in the published cohorts.

The survivor-specific problem. The cohorts that found accelerated epigenetic ageing in survivors measured specific clocks in specific populations with matched controls. A consumer kit result in one person has no such comparison and cannot be read against that literature. A survivor who buys one and is told they are biologically older has learned nothing they can act on, and may be frightened by a number that is within measurement noise.

What a person could do instead with the same money and the same motivation. The measurements on this page that have evidence behind them and are either free or nearly so: grip strength, a timed chair stand, a six-minute walk, blood pressure, and a blood count and biochemistry panel through ordinary care. The one intervention on this front with a randomised survival benefit is structured exercise after adjuvant chemotherapy for colon cancer, and it requires no test to start.

What would change this grade. A clock with published test-retest reliability on the exact assay sold, a published reference range for cancer survivors, and at least one trial showing that acting on the result changes an outcome. None of those exists at the time of writing, and the grade here is insufficient rather than harm because the test itself does no physical damage; the risk is the money, the false reassurance and the alarm.

## Fields

- Kind: Technology
- Status: emerging
- Last checked: 2026-10-02
- Tags: rejuvenation; survivorship; evidence:insufficient; objective; biological-ageing
- Principle: A consumer biological age result is a point estimate from a regression model applied to a noisy array measurement, reported without a confidence interval, without a stated reference population, and usually without naming which published clock it approximates. Every one of those omissions is necessary to interpret the number, and their absence is what makes the result uninterpretable rather than merely uncertain.
- Strengths: The underlying research literature is real, large and well documented; A reliability fix exists and is published, so a better consumer test is technically possible
- Limitations: Up to nine years of deviation between replicates for prominent clocks before the reliability correction; Array probe reliability is uneven and rarely reported; No clock is a validated clinical test and none guides a decision; No evidence that changing a clock reading changes an outcome; Consumer products rarely state which clock, which assay or which reference population

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Epigenetic_clock
- Higgins-Chen et al., A computational solution for bolstering reliability of epigenetic clocks: implications for clinical trials and longitudinal tracking (Nature Aging 2022): https://doi.org/10.1038/s43587-022-00248-2
- Sugden et al., Patterns of reliability: assessing the reproducibility and integrity of DNA methylation measurement (Patterns 2020): https://doi.org/10.1016/j.patter.2020.100014

## Connected records

- technologies: [Epigenetic age after cancer treatment](https://onco.cc/technologies/rejuv-age-epigenetic-clocks/), [Frailty and late effects in survivors](https://onco.cc/technologies/rejuv-age-frailty-and-late-effects/), [Measuring muscle and fat on scans the patient already had](https://onco.cc/technologies/rejuv-measure-body-composition/), [Structured exercise programmes after curative treatment](https://onco.cc/technologies/structured-exercise-survivorship/), [Telomere length after treatment](https://onco.cc/technologies/rejuv-age-telomere-length/), [Walking, gripping and standing up: the tests that take five minutes](https://onco.cc/technologies/rejuv-measure-functional-tests/), [What actually works after treatment](https://onco.cc/technologies/rejuv-frontier-what-works/)
- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Hodgkin lymphoma](https://onco.cc/cancers/hodgkin-lymphoma/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- fronts: [Recovery & Rejuvenation](https://onco.cc/fronts/rejuvenation/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- terms: [Late effects and survivorship toxicity](https://onco.cc/terms/late-effects/), [Quality of life](https://onco.cc/terms/quality-of-life/)
- bottlenecks: [Biomarkers are not validated or standardised](https://onco.cc/bottlenecks/b-biomarker-validation/), [Misinformation and unproven therapies](https://onco.cc/bottlenecks/b-misinformation/), [Survivorship and late effects are neglected](https://onco.cc/bottlenecks/b-survivorship/)

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