How do biological age tests work and are they accurate or helpful? : Shots - Health News Learning your DNA age sounds intriguing. But researchers caution the results might make you nervous. And they don't tell you much about what steps to take next.

You can order a test to find out your biological age. Is it worth it?

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In the era of direct-to-consumer testing, people don't have to wait for their doctors to order lab tests. From a few drops of blood or some saliva, it's possible to order up lots of information on ourselves, everything from food sensitivity tests to estimates of your biological age. But is it a good idea? NPR's Allison Aubrey reports.

ALLISON AUBREY, BYLINE: There's a lot of buzz about the idea that your chronological age, which is your actual age, doesn't necessarily match with your biological age, which is an estimate of how quickly or slowly you're aging. There are several ways to test this. At the Longevity Lab at Northwestern University, director Doug Vaughan uses a test called the GrimAge test. He says it's one indicator of your DNA age, something people may be interested in knowing.

DOUG VAUGHAN: I think knowing can provide a person with some additional information about the overall state of their health and provide some prediction for them about what they can look forward to in the years to come.

AUBREY: Of course, no test can tell you exactly how long you'll live. What the test can do is estimate your rate of aging compared to your peers. Scientist Steve Horvath spent years as a researcher at UCLA developing the concept. He explains as we age, changes occur in our DNA, and he found the pattern of these changes can act like a biological clock to estimate the age of a person's DNA.

STEVE HORVATH: You can use methylation, really, to measure time in all cells that contain DNA.

AUBREY: His research has found that people who smoke and those who have metabolic disease, for instance, tend to have accelerated rates of aging.

HORVATH: We spent over 10 years trying to understand what factors accelerate your epigenetic clock, and pretty much any lifestyle factor you know that is bad for you accelerates epigenetic clocks.

AUBREY: Conversely, if you exercise and eat a healthy diet, that slows methylation. Horvath says he developed the clock as a way for scientists to study aging. But the internet had a different idea. Online, there are now several different brands of biological age tests. You can mail off your sample and get results sent directly back to you. Horvath says he worries about the risk of people misinterpreting the results.

HORVATH: If you want to really arrive at an accurate estimate of lifespan, you should include clinical variables like blood pressure, glucose levels, lipid levels.

AUBREY: The results could create anxiety. Scientist Matt Kaeberlein, who is the founding director of the University of Washington's Healthy Aging and Longevity Research Institute, says eventually, these tests may give people specific information they can act on.

MATT KAEBERLEIN: Biological age tests are a part of the equation, but at this point, I don't think they're particularly actionable.

AUBREY: And since there are now multiple different brands and types of tests that haven't been rigorously reviewed by independent scientists, he says he'd be leery of ordering a test from a company that's also marketing anti-aging supplements.

KAEBERLEIN: I'm really worried about the idea of a test of uncertain validity or precision, and then you take the test, and then they tell you to buy their supplement, right? I mean, it really seems problematic to me.

AUBREY: When Dr. Vaughan uses the test in his lab, it's one of dozens of measures used to come up with a more comprehensive, integrative measure of aging.

VAUGHAN: GrimAge itself reflects DNA methylation, and that is certainly malleable. And the fact that it's malleable makes us think that we can potentially slow down the pace of aging in people or even turn back the clock in people.

AUBREY: And that's the true value. The test can help scientists measure whether it's possible to slow aging.

Allison Aubrey, NPR News.

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