Epigenetic clocks (DNA methylation) measure biological age using saliva or blood and are commercially available without a doctor. The association between a higher methylation age and health risks has been confirmed in large analyses, but applies as a group average, not as a personal prediction. Whether lifestyle changes genuinely lower epigenetic age and thereby reduce health risks has not yet been proven.
What an epigenetic clock tells you is not exactly how long you will live, but how your biological age compares to your calendar age. If your methylation age is running ahead of your actual age, that points to a higher risk compared with people of the same age in the general population. Two large analyses confirm that relationship, although it reflects an average pattern across thousands of people, not a personal prediction.
Measuring is straightforward: commercial providers send out a saliva or blood kit and no doctor is needed. However, the market varies considerably in quality. Choose a provider that is transparent about which method is used and that reports several clocks simultaneously, because different clocks measure something different and sometimes give divergent results for the same person. A single number from a single clock therefore says less than when multiple clocks point in the same direction.
The most useful way to use such a measurement is as a reference point to track trends over time, not as a statement about your future. Whether your epigenetic age truly decreases when you change your lifestyle, and whether that decrease also lowers your health risk, has not yet been proven. The test itself is harmless; the main risk lies in placing too much weight on one number or in the rejuvenation products that are often sold alongside it.
Reasonable evidence, 2 source(s); the direction is likely but not firmly proven.