Learn what your biological — not just chronological — age means for your health and the steps you can take to slow down the aging process.
Chronological age — the number of years you’ve lived on this planet — is seen as the number one predictor for many chronic diseases and overall mortality. Yet, there are still notable differences in health outcomes between individuals of the same age, says Calen Patrick Ryan, M.Sc., M.A., Ph.D., an associate research scientist at the Robert N. Butler Columbia Aging Center. Some people are fit and independent well into their 80s, while others see considerable declines in their well-being and functioning early on, says Ryan.
Enter: biological age, a metric that attempts to explain those differences in health outcomes associated with aging. “The idea of biological age is that there are processes underlying the changes associated with chronological age,” he explains. “How do you explain that heterogeneity between people, where one person looks old for their age, biologically speaking, and one person looks younger than we'd expect for their age? That's where the idea of biological age comes in.”
What’s more, knowing your biological age could give you a better picture of your health. Here, Ryan explains how biological age is determined and what you can do to potentially lower yours.
How Biological Age is Measured
Biological age can be measured by physiological changes, such as how fast you can walk or how quickly you can stand up from a chair, as well as molecular characteristics, says Ryan. The length of your telomeres (repetitive DNA sequences at the end of chromosomes) is a popular biological aging measurement and predictor. “Telomeres shorten with each cell division, so they get shorter and shorter throughout our lives,” says Ryan. “As they get to a critically short length, they're associated with issues in those cells. When you have many cells that are experiencing those critically short telomeres, you have a system that is aging more quickly than expected.”
A molecular biomarker called the epigenetic clock — also known as DNA methylation age — may also measure biological age, according to an article published in EBioMedicine. Epigenetic age has been shown to predict all-cause mortality independent of risk factors such as age, education, smoking, and physical activity, according to a 2016 meta-analysis published in Aging. And individuals whose epigenetic age is greater than their chronological age have been found to be at an increased risk for death from all causes, per the research.
In other words, biological age, when defined by clinical and molecular biomarkers, predicts overall mortality and aging-related diseases, sometimes more accurately than chronological age, according to Scientific Reports.
How to Slow Biological Aging
Biological aging is a rapidly developing scientific field, and many of the studies conducted thus far have been observational or correlational, says Ryan. “We're just at the cusp now of randomized control trials, which is really the gold standard for assessing the true effect of an intervention,” as you have a control group to compare the treatment group to, he notes. “If you look at a correlational study, for example, you might find that a certain diet might be associated with slower epigenetic age, but that diet might also be associated with [a certain] socioeconomic status, income, education, and a whole host of other things that are very difficult to control in the real world.”
Based on the studies currently available, eating a healthy diet, exercising regularly, and avoiding smoking are linked with improved biological age, says Ryan. Specifically, maintaining a high-quality diet has been associated with slower epigenetic aging, while exercise has been found to increase telomere length, research shows. Even reducing smoking over the course of a month has been shown to reduce biological age. “Some people may respond more or less to some of those interventions, but I think it’s pretty safe to say that everyone's going to respond somewhat,” says Ryan. “And there's very little to lose by exercising or eating better — the risks are extremely low.”
Minimizing caloric intake may also slow biological aging, says Ryan. In a 2023 randomized control trial that Ryan co-authored, participants either ate what they wanted or restricted their caloric intake by 25 percent for two years. “For one measure of epigenetic aging, we found that caloric restriction over a two-year time period was associated with slowing down the epigenetic clock,” says Ryan. “That effect was equivalent to about a 2 to 3 percent reduction in epigenetic age, which is similar in magnitude to reducing the mortality risk by about 10 to 15 percent.”
Of course, genetics do, in part, influence the way and the pace at which people age, says Ryan. “We know that if your parents live long and healthy lives, you're probably going to live a long and healthy life too,” he adds. Your environment also plays a role; for example, having educated parents appears to slow biological aging, says Ryan. “Everybody is different, and how our genes interact with our environment is different, so no one thing is going to work for everybody,” he explains. “But we do know the staples — eating healthy, not smoking, exercising — continue to stand as your best options [to slow biological aging].”
The Caveats
While there are steps you can take that may help slow your biological aging, the jury (read: research) is still out as to whether the effects last. “If somebody goes into a caloric restriction trial for two years and it says that they reduce their mortality risk by 10 to 15 percent, we don't know if that's still going to be true in 10 or 15 years,” says Ryan. “All we know is that we've moved the needle on this measure, which in other studies is strongly correlated with mortality risk and a whole host of health and cognitive outcomes in aging folks."
More research is needed to determine how these lifestyle factors affect people with different genotypes, he notes. And although the biological age measurements researchers test are becoming more accurate, “in some cases, you can take the same measurement from the same drop of blood — not just the same person, the same drop of blood — at the same time, and you might get variation in that [biological age] estimate,” says Ryan. The good news: The main methods that potentially slow biological age are proven to support overall health, so they’re well worth the effort.