Maybe age really is just a number.
Once my grandfather got up into his 80s, it became very hard for anyone outside the family to guess how old he really was. He was never stooped like other octogenarians, he retained a lush head of salt-and-pepper hair that he kept neatly combed, and on his long daily walks, he was sure-footed and moved at a brisk clip. He was sharp and articulate too, with impressive comedic timing and a fondness for pranks. Strangers who met him almost always just assumed he was 10 to 15 years younger.
We all know someone like this, a senior who seems just as vibrant and energetic as they did decades before. And we’ve all seen the reverse — someone whose years of hard drinking, smoking, or poor eating habits look to have taken their toll. There’s often a gap between a person’s actual age and how old a person appears to be based on how well their cells and organs function. Longevity researchers have been studying this mismatch for years and have determined that, yes, a person may be 70 based on their birth certificate, but they could have the heart of a 50-year-old or the muscle tone of someone who’s 60.
Gauging how well-preserved a person is, or what’s come to be called their “biological age,” is something scientists have puzzled over for years, says Daniel Belsky, Ph.D., a professor at Columbia University’s Aging Center. One of the earliest attempts to quantify it was in 1969, when Alex Comfort, a British scientist best known for his bestseller The Joy of Sex, proposed a test to measure the rate of aging in humans. In the years since we’ve come a lot closer to creating something akin to a biological age calculator, and a flurry of medical startups have developed their own battery of tests. But how do they work? And are they actually reliable? Here’s what to know.
The hallmarks of aging
Longevity science took a great leap forward when researchers discovered a set of molecular changes in a number of different species that control how fast or slow the body breaks down — called the hallmarks of aging. These include DNA damage; changes to our mitochondria, which you may remember from high school biology is the “powerhouse of the cell”; and telomere attrition. (Telomeres are the protective caps on the ends of our chromosomes. They’re a little like the plastic tips at the end of our shoelaces. They shorten as we get older and eventually can’t keep our shoelaces from unraveling, Mark Hyman, M.D., who Katie spoke with recently about longevity, writes in his new book, Young Forever.)
There are other hallmarks, too — and researchers are still discovering more each year. All of them progress over time, beginning from when we’re very young. As they gradually accumulate (rapidly if you’re chronically stressed or never exercise, or more slowly if you’re maintaining a healthy diet), they cause our tissues and organs to become less resilient and break down. Ultimately, Dr. Belsky explains, that “makes us more vulnerable to disease or disability, and eventually kills us.” The hope is that one day, scientists will be able to create therapies that target these markers and slow the biological clock. Some of these interventions already exist, but don’t go calling your doctor just yet: They’re only available to aging-anxious fruit flies and tiny roundworms called the Caenorhabditis elegans. Scientists have been able to manipulate the genes of these creatures to correct the alterations in their mitochondria, for example, significantly extending their lifespans.
Researchers haven’t quite cracked how to do the same for humans, but Dr. Hyman tells us that these treatments aren’t far off. What is clear, however, is that optimizing our diets, getting the proper amount of sleep, and regularly exercising are simple tasks that act a bit like a fountain of youth on their own. That’s why people like my grandfather, who believed in a diet rich in vegetables grown himself and void of anything too greasy or too sugary, may be years younger than they look.
How do biological age tests work?
There’s been a boom in companies offering to tell you how old you “really” are…for a few hundred bucks. Some of these claim to calculate your biological age using information gathered from a FitBit or other wearable tech, like heart rate or body temperature, or with bloodwork to measure things like your level of inflammation, triglycerides, and cortisol. Segterra, a nutrition company that boasts an impressive roster of MIT and Harvard-trained scientists, has a blood test called InsideTracker that’ll set you back about $250 and promises to analyze more than a dozen biomarkers (physiological indicators that can gauge how healthy you are in the moment and how likely you are to develop certain diseases) and provides customized nutrition, exercise, and supplement recommendations.
Other startups have focused on analyzing your DNA. Dr. Hyman used one that measured the length of his telomeres. (A test he took at 58 told the Pegan Diet author that his biological age was 39.) Telomeres, as we discussed earlier, shorten over time but can also deteriorate faster if you smoke or are under chronic stress. They can lengthen too, a discovery that won a trio of American scientists the Nobel Prize in 2009.
A new generation of age gauges has turned to DNA methylation assessments. Methylation refers to the clusters of atoms, called methyl groups, which glom onto our genes, switching them on or off. Studies show that we may be able to predict how old someone is based on their pattern of expressed and silenced genes. TruDiagnostic will run a blood-based DNA methylation test for $499, while Elysium Health has a saliva test that costs $299.
That’s a lot of dough to spend on something so theoretical (and potentially, extremely depressing — imagine spending hundreds to learn that it’s not just your lower back that seems 20 years older than it should be, but your entire body.) But Michael Roizen, M.D., an anesthesiologist who created one of the first bio age calculators using a questionnaire over 20 years ago, says it may be worth giving one of these tests a whirl, simply to have a rough estimate of how likely you are to develop age-related diseases like dementia or diabetes.
This information can serve as a powerful motivator. Those of us without a medical background may not fully grasp what our lipid panel says about our health, but all of us get what it means when a test says that you may be Gen X on paper, but you’ve got the body of a Baby Boomer. When Dr. Roizen framed it that way to a patient, by telling him that his pack of cigarettes a day had made him eight years older, the man was finally able to quit.
For this reason, Dr. Belsky thinks that getting a biological age reading may one day be part of a routine checkup. For now, he believes that they do provide some value, but it’s best to take your results with a grain of salt.
“I would encourage people to interpret the information they would get from one of these tests in consultation with a healthcare professional, with a healthy degree of skepticism, and a good sense of humor,” he says. “They’re not perfect yet.”
