Longevity Testing:
Which Ageing Tests Are Worth It and Which Are Hype

Longevity clinics and online companies now offer a growing menu of tests: epigenetic "biological age" kits, telomere tests, full-body MRI scans, genetic panels, organ age tests and continuous glucose monitors for healthy people. Some are useful, many are unproven, and a few can cause harm. Full-body MRI is a good example: the American College of Radiology doesn't support it for people without symptoms or risk factors, because "there is no documented evidence that total body screening is cost-efficient or effective in prolonging life". In studies of screening scans, about 95% of people had some abnormal finding, about 30% needed further evaluation, and around 1.5-2% had a suspected or confirmed cancer. Epigenetic age tests are valuable research tools, but as their pioneer Steve Horvath says, "It's not yet possible that you can go to different validated labs and get the same readout." Meanwhile, some simple, inexpensive measures are powerful predictors of long life. In a study of 122,007 people, those with elite cardiorespiratory fitness had an 80% lower risk of death than those with low fitness, a bigger difference than for smoking or diabetes. This article explains which tests are worth doing and which to question.

Key numbers

Why more testing isn't always better

A useful test must be accurate and reliable, and its result must lead to an action that improves health. Many longevity tests fall short: they measure something that hasn't been shown to change outcomes, give different results from different laboratories, or uncover harmless findings that lead to anxiety, further tests and procedures. On the other hand, some well-established measures are underused.

Evidence strength

Strong: proven measures that predict health.

• Blood pressure, cholesterol, blood sugar and HbA1c, kidney and liver function: inexpensive, reliable and linked to treatments that reduce disease (see Nutrient Blood Tests).
• Cardiorespiratory fitness: in a 2018 study in JAMA Network Open of 122,007 patients who had treadmill exercise tests, those with elite fitness had an 80% lower risk of death over a median of 8.4 years than those with low fitness. By comparison, smoking was linked to 41% and diabetes to 40% higher risk. The authors concluded that "cardiorespiratory fitness is a modifiable indicator of long-term mortality".
• Guideline-based cancer screening, such as bowel, breast and cervical screening at recommended ages.

Strong: full-body MRI in healthy people isn't recommended. In 2023, the American College of Radiology stated that it does not support total body MRI screening in people without symptoms, risk factors or relevant family history, noting there's "no documented evidence that total body screening is cost-efficient or effective in prolonging life". It warned that scans uncover "numerous non-specific findings that will not ultimately improve patients' health", leading to "unnecessary follow-up testing and procedures, as well as significant expense". Reviews of screening studies have found abnormal findings in about 95% of people, with about 30% needing further evaluation and 91% of lesions turning out to be benign; about 1.5% of people screened had a confirmed cancer. Whether finding these cancers improves survival hasn't been shown. Scans typically cost thousands of US dollars.

Moderate: epigenetic age tests are research tools, not yet personal tools. Epigenetic clocks predict health outcomes in large studies (see Epigenetic Clocks Explained). But for individuals, results can vary with the clock, the laboratory, the measurement method and the sample. Horvath has warned that applying blood-trained clocks to saliva "without correction, the errors can be substantial", and that the tests were "designed for epidemiological studies, not individuals". Early clocks could differ by up to 9 years when the same sample was tested twice, and biological age can rise temporarily during illness or stress (see Can You Reverse Your Biological Age?).

Limited: other popular longevity tests.

• Telomere length tests: described as "premature" by leading researchers, because longer telomeres raise some cancer risks while lowering others (see Telomeres and Ageing).
• Organ age tests: promising in research, but not yet validated for routine clinical use (see Organ Ageing Clocks).
• Direct-to-consumer genetic longevity panels: most longevity genes have tiny effects, and results such as APOE ε4 can cause anxiety without changing what you should do (see The Genetics of Longevity).
• Continuous glucose monitors for healthy people: see Continuous Glucose Monitors Without Diabetes.

Important limitations.

• False reassurance: a "young" test result can lead people to neglect proven prevention.
• Overdiagnosis: finding harmless abnormalities can lead to unnecessary procedures with real risks.
• Cost: many tests are expensive, not covered by insurance, and repeated over time.
• Conflicts of interest: companies selling tests often fund or publish the research behind them.

Recommendations by situation

Practical notes

The most valuable longevity "tests" are often the simplest: knowing your blood pressure, cholesterol, blood sugar, weight, waist size and fitness, and keeping up with recommended cancer screening. These are cheap, reliable and lead directly to actions that prevent disease. Newer tests may become useful as evidence grows, but for now, ask three questions before paying for one: Is it accurate and reliable? Will the result change what I do? Is there evidence that acting on it improves health? Our Longevity Doctors use evidence-based testing tailored to your risks, starting with the free longevity assessment.