What is My Biological Age?

Traditional wisdom would have us thinking that how we age is all in our genes. And while that may be one indicator of healthy aging, it certainly isn't the be-all and end-all of how we age. It turns out there are other factors—some you might not even realize—that are tied to the aging process. But how exactly can we get an indicator of where we really stand—and whether our anti-aging efforts are doing as much as we think they are? In other words, how do you determine your "real" age?

Enter biological age lab testing.

What is your biological age?

It seems straightforward, right? Isn't your age just your age? Before we get into the ins and outs of what biological age means and why it's important for you to understand, we might want to talk about aging in general. Specifically, chronological age.

Chronological age is the concept you're probably most familiar with: it's quite literally how long you've existed on this planet, from the day you were born. For example, if you're 65 years old, your chronological age would be 65. If you're 28 years old, your chronological age is 28. Simply put, chronological age encompasses the quantifiable amount of time you've been alive. But that number could be completely different from your biological age.

Your biological age is a lab-based estimate that reflects the accumulated biological stress on your DNA and your body. It tells you whether you are biologically older or younger than your chronological age. Knowing your biological age can help you understand your predicted healthspan (the period of your life free from age-related diseases) and overall life expectancy. It can also help guide you in making choices that keep you young at the cellular level—which is crucial to your longevity!

A combination of factors might contribute to the aging process and how the numbers for biological age are calculated. For example, are you a requisite couch potato or do you never miss a chance to get some physical activity in? Are you surviving on that second cup of coffee to get you through the day or do you get 7-9 hours of sleep each night? Do you follow healthy eating habits and live a lifestyle that actively supports healthy longevity? To put it plainly: everyone ages differently, and your lifestyle choices can impact the rate at which you age.

Can you test your biological age?

While it might sound like an abstract concept in theory, testing your biological age is actually very easy! There are several different tools available that will give you a more comprehensive lowdown on your aging.

While the results may not be reminiscent of a traditional lab test that tests for factors like glucose and cholesterol, the data for most biological age tests are collected in a familiar way—using a blood test. More specifically, a finger stick blood sample. Some tests even offer at-home collection of samples.

How biological age is calculated

There are a variety of tools that can provide a look at your biological age. Some are even as simple as looking at a photograph—like one cohort study of twins in Denmark that discovered perceived age in photographs could provide an accurate estimate of biological age. However, knowing your numbers through epigenetic lab testing is more comprehensive and one of the best ways to discover your closest true biological age. You may want to look out for tools that report on the following:

• Intrinsic biological age

  —This is simply a measure of epigenetic factors that help determine your biological age in comparison to your chronological age. This tool will give you a biological age estimate that will reflect if you are internally older or younger compared to the age your birth certificate says you are!

• Extrinsic immune age

  —This type of tool helps you better understand how your immune cells are aging and how that impacts how you're aging. It measures epigenetic changes in your immune cells and how those changes relate to age-associated weakening of the immune system (also known as immune senescence). A tool that calculates immune age will look at the percentage values of your immune cells and determine how your biological aging is being affected.

• DunedinPACE

  —DunedinPACE is an algorithm that correlates your epigenetic age with physical aging characteristics to give an estimate of your rate of aging. It estimates how well you might do on typical aging metrics (including things like one-leg balance, grip strength, IQ changes from childhood to age 45, and even how your face ages). It also correlates your epigenetic signature with mortality and chronic disease risks. Tests that use the DunedinPACE algorithm will assign you a number that can tell you how many biological years you are aging per chronological years.

• Average telomere length

  —Telomeres are the protective caps at the ends of DNA chromosomes (think about the ends of shoelaces). When cells divide, telomeres shorten. The length of them is important because longer telomeres are commonly associated with longevity. Identifying your average telomere length is an important marker to look for to get a better idea of your biological age—most tests will compare your telomeres directly against others in your chronological age group. 

• Weight loss response

  —Some people respond better to caloric restriction than others and this has been associated with certain epigenetic factors. Thinking about incorporating a low-calorie diet into your lifestyle? Results from a test that reports on weight loss response can help provide insight into how well you may respond to calorie restriction as a weight-loss strategy.

• Exposure to smoking

  —This is important, regardless of whether you're determining your age or not. Smoking not only heightens your mortality risk, but it also negatively impacts your overall health, contributing to things like high blood pressure, heart disease and other chronic diseases, especially lung diseases. A tool like this gives a DNA methylation measure of your exposure to cigarette smoke (be that direct or second-hand) and of your risk of developing smoking-related health conditions.

• Impact of alcohol consumption

  —Similar to smoking (minus secondhand exposure), this kind of test will give you a DNA methylation score of alcohol exposure and compare it against your self-reported drinking frequency and the scores of others who've tested for this.

Are biological age tests accurate?

While biological age tests are reproducible (an important facet of accuracy), it's important to remember that biological age calculators are tools and merely provide an estimate of how you're aging. They should not be taken as the final (or only) word in terms of how you are aging. That being said, testing for these particular markers should be taken seriously, and can help guide you in making positive lifestyle changes. After all, we all want to support healthy aging!

Can biological age be reversed?

While you can't completely slow down the clock on your actual age, you can make choices that can reverse some of those epigenetic biomarkers that contribute to your biological age. And good news! Much like the healthy lifestyle choices you might make to minimize risk of disease and other ailments, reversing biological age uses the same playbook.

Some ways you can take control of your biological aging include:

• Minimizing chronic stress—whether that's from a stressful work or home environment (or both!)
• Prioritizing a healthy diet and optimal amounts of sleep
• Maintaining a healthy weight and getting regular exercise
• If you're a smoker, quitting can help you slow down aging and lower your biological age
• Take charge of your nutrition—address any nutrient deficiencies you may have

Once you've started making these changes and feel like you're taking charge of your health, it might be time to retest. Though testing once a year is a standard recommended time period for follow up, if the efforts you have been making are significant, you can retest after 4-6 months, and reassess any lifestyle changes from there.

References

• Christensen, Kaare, et al. "Perceived age as clinically useful biomarker of ageing: cohort study." BMJ. December 2009. https://pubmed.ncbi.nlm.nih.gov/20008378/
• DePolo, Jamie. "Older Biological Age Compared to Chronological Age Linked to Increased Breast Cancer Risk." BreastCancer.org. February 2019. https://www.breastcancer.org/research-news/biological-vs-chronological-age-and-risk
• Jazwinski, Michal S., et al. "Examinations of the Dimensions of Biological Age." Frontiers in Genetics. March 2019. https://www.frontiersin.org/articles/10.3389/fgene.2019.00263/full
• Wu, Julia W., et al. "Biological age in healthy elderly predicts aging-related diseases, including dementia." Scientific Reports. August 2021. https://www.nature.com/articles/s41598-021-95425-5  
• "What is Epigenetics?" Centers for Disease Control and Prevention. https://www.cdc.gov/genomics/disease/epigenetics.htm
• "What is Your Actual Age?" Northwestern Medicine. June 2022. https://www.nm.org/healthbeat/medical-advances/science-and-research/What-is-Your-Actual-Age