Believe it or not, your chronological age (the amount of years you’ve been on earth) and your biological age are two very different things. Put simply: Even if two people are 45 years old, they are both engineers, and they live in the same city, one could be aging way faster than the other.
“The question that’s most important to people is not ‘how old am I?’ but ‘how long have I got to live?’ — and biological age attempts to answer that,” says John Beard, PhD, professor and director of the International Longevity Center at Columbia University in New York City.
There are many complex and dynamic biological changes that underpin aging and contribute to your risk of disease and functional decline, Dr. Beard says. “Biological age is about identifying the underlying changes driving all of that.” The bevy of factors include your diet, fitness and exercise, sleep, hobbies, genetics, and stress level. So if you’re 45, but you feel all of 65, your biological age is one clue as to why.
Chronological Age vs. Biological Age
Chronological age is a measure of time, and biological age is a measure of health.
“Biological age is an attempt to estimate an individual’s physiologic age in order to more accurately reflect their functionality and risk of age-related diseases or death,” says Alexandra White, PhD, a cancer epidemiologist at the National Institute of Environmental Health Sciences in Durham, North Carolina.
How Is Biological Age Measured?
This is where things get tricky.
“People have tried to measure biological age by looking at various internal biomarkers or physical manifestations of aging, and there are a lot of them,” says Michal Jazwinski, PhD, director of the Tulane University Center for Aging in New Orleans. Biomarkers can be things like your cholesterol levels, your hormones, or toxins in your major organs, for example.
“If you look at just one of these biomarkers, it probably won’t tell you much,” he explains. “So what a lot of people have tried to do is to take a bunch of these — a dozen or more — and generate an algorithm that combines them into one measure of biological age.”
There are also several DNA-based measures of biological age that are now being studied either alone or in combination with other biomarkers.
Should You Take a Biological Age Test?
Online companies and calculators do offer biological age estimates, but experts say their validity is still shaky at this point. “There are all sorts of people working in different fields — whether telomere length or inflammatory markers — and this work is increasing our understanding and giving us a more nuanced picture of health and aging. But we’re a ways away from identifying some test that tells you everything you want to know,” says Beard.
Various labs offer testing kits that range from $249 to $499 that will measure your epigenetic or biological age, says Steve Horvath, PhD, a professor of human genetics and biostatistics at UCLA in Los Angeles. With that said, there is still no scientific consensus about how to best measure biological age, so be mindful of the tests’ limitations. “My recommendation is to use epigenetic testing for scientific research only at this point.”
If you want to get a helpful assessment of your health status, Dr. Horvath says visiting a doctor and having a thorough exam — weight, blood pressure, a full blood panel that measures your cholesterol and blood sugar — is still the way to go.
“Tests that are commercially available should not be taken to be more meaningful than a doctor’s assessment,” he says. “Getting an epigenetic test may give an individual the wrong answer and cause that person to become overly worried or stressed.”
Could Knowing Your Biological Age Help You Live Longer?
The moonshot hope is that someday biological aging breakthroughs could lead to the development of interventions that stop or even roll back the aging process — either in a specific part of the body or throughout it.
Researchers are looking into various treatments to reverse epigenetic aging, says Horvath. He mentions efforts targeting the thalamus as well as nerve cells in the eye. “No treatment has been approved yet for rejuvenating humans,” he adds. But, hopefully, those are coming.
Experts also say that as measurements of biological aging become more refined, they should help doctors and other care providers offer more effective individualized treatments for their patients.
Beard offers an example. “When it comes to physical activity, we still give people pretty generic advice that may not suit everybody,” he says. Accurate biological age estimates could help researchers better assess different forms of exercise and so help doctors give more useful and specific guidance — more walking for this patient, more high-intensity interval training for that one.
“I think we’re going to go through a transformative period where, rather than looking at people as batches of diseases, we’re going to look more holistically at the underlying drivers of aging and illness,” Beard says.
The concept of biological aging will underpin that transformation, he says. But medical science still has a lot of work to do to take us there.
Tips to (Possibly) Slow Down Your Biological Age
While there’s still no one-size-fits-all approach to turn back time on your biological clock, there are still plenty of ways to support longevity. Scientists have gleaned many insights from the Blue Zones around the world, the areas where a significant portion of residents live past the age of 100.
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