Knowing—and manipulating—your 'biological age' is certainly en vogue right, with longevity bros and our surging wellness era taking centre stage in the public consciousness. But while it may be trendy to be able to tell someone your biological age at a party (hint: it's not your birthday), most common commercial biological aging tests using a spit sample or oral swab may not actually be the best or most accurate way to get the right answer, according to new research.
A study, which was published in January in the journal Aging Cell, breaks down the different methods scientists use to measure biological aging, and suggest that some of these methods are better than others.
Here’s what the study found, plus the best way to learn your most accurate biological age.
Meet the experts: Sandra Narayanan, MD, is a vascular neurologist and neurointerventional surgeon at the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA; Abner Apsley is the lead study author and a doctoral candidate at Penn State.
What did the study find?
The study focused on epigenetic clocks, which are biochemical tests that can measure age based on gene expression, helping you compare your biological age with your chronological age. (Epigenetic clocks, which are usually done with blood tests, look at tissue samples from a large number of people and then look at differences in genetic markers across the lifespan.)
For the study, the researchers analysed 284 tissue samples from 83 people between the ages of nine and 70. Overall, they looked at five types of tissue samples and stacked them up against seven epigenetic clocks.
The researchers discovered that in six of the seven clocks that were tested, oral tissue had less accurate estimates of biological age compared with blood samples. In some situations, the biological ages were up to 30 years off, which is kind of a big deal.
The findings highlight 'the need for careful consideration of tissue type when estimating epigenetic age', the researchers wrote.
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What is biological age?
Biological age is different from your chronological age. 'Chronological age is time since birth and is measured in absolute terms—years', explains Sandra Narayanan, MD, a vascular neurologist and neurointerventional surgeon, of the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA.
But your biological age describes 'subtle' things that happen in your body that influence how old or dysfunctional your cells and tissues are, Dr. Narayanan says. You can think of it like your body's age versus your actual age. And while everyone ages at the same rate chronologically, their bodies and tissues may age at faster or slower rates.
What kinds of tissues are used for estimating biological age?
It depends on how you’re tested. Many commercial tests and studies use oral tissue, like your spit or swabs from the inside of your cheek, says Abner Apsley, the lead study author and a doctoral candidate at Penn State.
But you can also use blood testing to determine biological age, he points out. And based on the study results, it seems like this is the best way to go if you want a really accurate answer.
For this study, they used the following tissues: buccal epithelial, saliva, dry blood spots, buffy coat (part of the blood that contains the most leukocytes), and peripheral blood mononuclear cells.
Why doesn't oral tissue work as well?
Most epigenetic clocks were created using blood tissue, Apsley says, so using oral tissue to try to determine biological age didn’t result in an accurate number, based on the study findings. Basically, using oral swabs and stacking it against data from blood tissue is like trying to compare apples to oranges.
'Because most clocks have been constructed using blood tissue, it follows that blood tissue is generally the most ‘accurate,' Apsley says.
What can my biological age tell me?
In general, an (accurate) biological age can give you a look at your current health, Apsley says. 'Having a higher predicted biological age than chronological age has been shown to be associated with a host of aging-related diseases such as Alzheimer's, cancer, and cardiovascular diseases', he says. 'Knowing that you have a high biological age may be motivating to start practicing more healthy eating and exercise habits, which have been shown to decrease biological age predictions.'
And, of course, if you have a low biological age, you can feel good good about the health habits you already have in place.
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