Epigenetic age tests

In large groups, the clocks work as research tools. The first multi-tissue clock estimated age from 353 methylation sites across most human tissues [1]. Later clocks trained on health data rather than age alone, PhenoAge and GrimAge, predicted death, heart disease and cancer better than age did [2] [3], and DunedinPACE, built from 20 years of decline in one birth cohort, predicted illness, disability and death [4]. A meta-analysis found that each 5 years of extra methylation age went with an 8 to 15% higher risk of death, while links with specific diseases were inconsistent [5].

For one person, the numbers are noisy. Technical noise alone moved six popular clocks by up to 9 years between repeat runs of the same sample [6], so a change of a few years between two consumer tests may be measurement error. Different clocks and companies can also disagree, and there are no shared standards between companies [7].

In trials, healthy habits move the clocks only a little. Two years of calorie restriction slightly slowed DunedinPACE but not other clocks [8], and 3 years of omega-3 slowed several clocks by about 3 to 4 months [9]. No study has shown that lowering a clock score lengthens life, and none has tested whether personal testing improves health. These are not diagnostic tests; even Bryan Johnson's page calls biological age claims preliminary [10].

• The sample is a blood draw, finger prick or cheek swab, so the physical risk is small. The main risk is acting on a noisy number.
• Repeat runs of the same sample can differ by years on popular clocks, and different clocks or companies can give one person different ages.
• These tests do not diagnose disease. A young score does not replace standard checks such as blood pressure, cholesterol, blood sugar and cancer screening.
• Many people who share their results have ties to test sellers: David Sinclair co-founded Tally Health, Steve Horvath founded a nonprofit that holds licenses to several of his clocks, and Mike Lustgarten shares TruDiagnostic discount codes.
• Results are health data. Check how a company stores, shares and deletes your sample and results before you buy.