- A "biological age" is meant to measure how healthy people's cells and organs are.
- Many people are trying to slow down their biological clocks by using supplements, medicines, and lifestyle changes.
The buzzy term "biological age" suggests there may be a more complex and precise, scientific answer to the straightforward question "how old are you?" — one that can't simply be answered by measuring the amount of time a person has spent on Earth.
Longevity scientists, doctors, and geneticists are starting to coalesce around the idea that it's possible people may have a "biological age" which can be different from their "chronological age," the number measured from the day they were born.
According to the National Institute on Aging, our "biological age means the true age that our cells, tissues, and organ systems appear to be, based on biochemistry."
But the idea that there is one, specific, numeric biological age to pinpoint for each of us is still controversial, in large part because it is difficult to say for sure that there's a "normal" way our cells should look at any given age, or that being "biologically young" is actually any different from staying healthy and fit as we age.
"The core concept is that not everyone who's been on Earth the same number of years is equally healthy," longevity researcher Martin Borch Jensen, the co-founder of Gordian Biotechnology, told Insider.
Here's what we know about biological age — and what we don't:
The people who claim they reverse-aged their cells
Dr. Mark Hyman, a family physician who is the founder of the UltraWellness Center, recently told Insider he's — biologically speaking, 43 years old — a full 20 years younger than what the official timekeeping records would suggest. Hyman credits the youthful vibe his cells appear to have to a daily regimen that includes morning meditation, breakfast smoothies, and strength training.
45-year-old biotech founder Bryan Johnson spends about $2 million a year on special pills, smoothies, plus a team of more than 30 doctors and health experts, in an elaborate quest to reverse his aging. According to a recent Bloomberg profile, Johnson claims recent tests suggest his heart is like a 37-year-old's, his skin looks 28, and his lungs are like a teenager's.
Then there was the 69-year-old Dutch man who tried to subtract 20 years from his legal age in 2018, because he said he "feels" younger. (A court said no way.)
The problem with all of these calculations, Jensen said, is that there is not and has never been any scientific consensus around the definition of a true biological age.
"Is your lung function more important than your skin, or less important — what about your blood inflammation levels?" he said. "How do we weigh all these things? Nobody knows. You can sort of wave your arms and say, 'well look, this person, they're in really good shape, so they're probably younger,' but it's not quantitative."
Science is racing to catch up
So far, no one has figured out how to definitively reverse or slow human aging — though it has been achieved in other organisms.
"There is no reason to doubt that that is possible, given we can do it in multiple other species," Jensen said.
The field of biological aging research in humans has progressed immensely over the past decade. Recent studies have used blood tests to try to predict when a person may develop age-related diseases and decline, such as heart disease or memory loss.
But two important questions remain unanswered: can we use such markers to effectively determine everyone's exact biological age? And, can we target those tell-tale aging markers to make people younger again?
Some private companies have already started offering pricey at-home spit tests that purport to tell you just how biologically old you are. But many experts are still cautious about that promise, in part because of what Jensen calls the long "history of BS in the aging field," which goes back many thousands of years.
Searching for the elixir of youth in weight-loss drugs, diet, and meditation
Dr. Nir Barzilai suspects that it may be possible to "target aging" and bring down one's biological age with drugs like metformin and rapamycin.
"We all have biological age and chronological age," Barzilai, a researcher hoping to develop a whole new class of US Food and Drug Administration-approved anti-aging treatments, called geroprotectors, recently told Insider. "Somebody who's 50 can be 40, biologically, or 60."
Both drugs could slow down aging at the cellular level, thereby reducing the onset of cancers, dementias, and type 2 diabetes. But, so far the research is inconclusive. While some people are trying to use metformin to slow aging, so far, no geroprotector drugs have been FDA-approved for that purpose.
Other anti-aging practices that have been shown to have an impact on peoples' longevity and healthspan include eating well, exercising, meditating, and maintaining strong community ties with family, friends, and spouses. In this regard, being biologically young may just be a proxy for social privilege — not everyone has equal access to the clean air, fresh drinking water, ample leisure time, and healthful foods that make life easier on our DNA.
Scientists think part of the reason these practices work to keep people alive for longer than their peers is because they help maintain the fitness of our cells.
Biological age is just a fancy new way to talk about health, some experts say
For now, any attempts to precisely quantify a person's biological age should be treated as novelty numbers — they're an oversimplification of what we know (and don't know) about how aging works inside the body.
Just because you're old, healthy, and your tissue and cell health suggests you're ready to keep on living life for many more years to come doesn't mean you're magically young again. Your health status could just mean you've got genes that age well, and that as a result, you're less likely than your peers to die soon.
Jensen hopes that, in the future, scientists will not only be able to "measure stuff in your blood" that can predict disease onset, but that there will also be treatments developed that "broadly affect multiple diseases," so people can continue living healthier lives until their death. On Monday, a group of bipartisan lawmakers from New York, Texas, California, and Florida started a new congressional longevity caucus aimed at doing just that.
"There's no evidence that that's impossible," Jensen said. "We're not there yet," he cautioned, but "we should go for it."