Chronological Vs. Biological Age and Why Chronological Age Matters Less
Although you may consider your age to be the number of candles on your birthday cake each year, how fast our cells and organs are aging is another story—and this is the key difference between chronological and biological age. While chronological and biological age tend to line up during our younger years, they can drift further apart as we grow older.
With an accelerated biological age, you’re more likely to experience an earlier onset of age-related diseases and bodily decline. Conversely, maintaining healthy habits throughout life can keep you biologically young regardless of chronological age. In this article, we’ll dive deeper into why chronological age doesn’t matter as much when it comes to healthspan and lifespan and some of the critical factors influencing biological age.
Chronological Vs. Biological Age
If you’ve ever met a 65-year-old who looks two decades younger—or, conversely, a 45-year-old who looks like they’re headed for retirement—you can intuitively understand the difference between biological and chronological age. Although biological age is primarily internal, much of it can show up externally in how aged or frail our faces and bodies appear.
As opposed to the chronological age that measures the number of years you’ve spent on earth, biological age assesses damage and dysfunction to cellular markers. Researchers use a multitude of biological methods to indicate how quickly your cells, organs, and tissues are deteriorating, ranging from telomere length to epigenetic changes to serum biomarkers.
Although chronological age is undoubtedly important—you wouldn’t expect an 85-year-old and 25-year-old to have the same health status, for example—it seems to matter much less than our biological age when it comes to how well we age. With the understanding that people age at different rates internally, many researchers are now looking to biological age to understand longevity better.
Factors That Influence Biological Age
While some things are out of our control when it comes to aging (like genetics), many other factors within our control influence biological age. The choices we make every day can impact various cellular and physiological processes that either speed up or slow down the aging process, meaning much of aging is within your control.
Foods high in refined sugar or carbohydrates, highly processed ingredients, or excessive saturated fats can promote pro-inflammatory pathways that lead to oxidative stress and accelerated aging. The reverse—avoiding these foods and adding those rich in fiber, monounsaturated fats, omega-3 fats, protein, and antioxidants—can reduce biological age.
Nutrients found in these foods support cellular health and help maintain DNA integrity. For example, omega-3s benefit cell membrane health and can ward off a loss of telomere length following stressful events.
In a clinical trial, specific dietary and lifestyle changes were found to impact biological age in middle- to older-aged men. Remarkably, this short 8-week study reversed biological age by over three years, providing the first-ever evidence in a human trial that nutrition and lifestyle habits alone can turn back the aging clock. The diet was rich in polyphenols (like curcumin, EGCG in green tea, quercetin, and rosmarinic acid in herbs), berries, beets, cruciferous vegetables, herbs, spices, and moderate amounts of high-quality animal proteins like grass-fed beef, eggs, and liver.
Like diet, a solid exercise routine can reduce biological age and improve just about every aspect of health. In addition to lowering oxidative stress and promoting healthier inflammatory pathways, exercise has been linked to the preservation of telomere length.
In a meta-analysis of almost 1,000 participants, exercise was found to be beneficial for telomere length—especially aerobic exercise that lasted for more than six months.
Similarly, in research with mice, a combination of resistance and endurance exercise reduced skeletal muscle biological age by 10%.
Stress and Mental Health
In a study of 3,000 people, researchers combined data from five biological clocks to determine which factors accelerated internal aging. Somewhat surprisingly, a major determinant of increased biological age was found to be the presence of mental health or mood disorders, especially depressive symptoms.
Chronic stress is also known to increase aspects of biological age, especially DNA damage, telomere length, cellular senescence, and inflammatory responses.
Chronic health conditions and accelerated aging are a “chicken or the egg” scenario—does the health condition lead to increased biological age, or do factors like telomere loss and DNA damage lead to disease development? The answer is likely both, or somewhere in the middle, as things like oxidative stress or inflammatory imbalances can cause both chronic health conditions and hallmarks of aging like mitochondrial dysfunction and telomere attrition. Many chronic diseases can also damage organs and tissues, reducing their functionality, accelerating biological age, and furthering health complications or conditions.
In the previously mentioned study of 3,000 people, accelerated biological age was also associated with higher BMI (Body Mass Index) and several chronic disease states, including those related to endocrine and metabolic health. People with a cluster of symptoms, including higher blood pressure and blood sugar, excess body fat, and increased waist circumference and triglycerides, were also tied to advanced biological aging.
Sleep is vital for cellular repair processes, removing damaged cells and cell parts to slow aging. Without adequate sleep, dysfunctional cells can remain in the body, creating oxidative damage.
Research suggests that shorter sleep duration is associated with shorter telomeres. Some studies have found an inverse correlation between the number of hours slept per night and telomere length in certain populations, and others have shown that short sleep accelerates epigenetic age.
Smoking and Alcohol
Most people are aware that smoking and drinking excessive alcohol are not the healthiest choices—but it goes far beyond lung and liver health. Smoking and alcohol use can increase oxidative stress, DNA damage, and inflammatory markers while also weakening the immune system, causing organ dysfunction, and interfering with critical metabolic processes.
While chronological age undoubtedly matters when it comes to longevity, biological age matters more. With more and more research and technologies to determine aspects of biological age emerging, it should soon be simpler and more accessible for everyone to assess their internal age—and, with it, their risk for age-related diseases and mortality. As we gain more knowledge about our biological ages, we can focus on lifestyle modifications and interventions within our control to slow down the aging process and lengthen our healthspans and lifespans.
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