While our birth certificate tells us our chronological age, science offers a way to measure our “biological age,” reflecting the true age of our cells, tissues, and organ systems. This concept is explored through epigenetic aging, a field that examines how behaviors and the environment can lead to changes affecting how our genes function, ultimately influencing this biological age.
The Science of Epigenetic Marks
At the heart of epigenetic aging lies a biological mechanism called DNA methylation. This process involves adding tiny chemical tags, known as methyl groups, to specific points on our DNA, typically at cytosine bases. These methyl groups act like “dimmer switches” or “punctuation marks” on our genetic code, influencing whether a gene is turned “on” or “off,” or how strongly it is expressed. The DNA sequence itself remains unchanged, but its readability for cellular machinery is altered.
As we progress through life, the patterns of these methylation marks undergo predictable changes. Some sites gain methylation, while others lose it, and this shifting landscape of chemical tags reflects the passage of time within our cells. These modifications are a natural part of development and aging, contributing to the diversity of cell functions in the body. However, external factors can also influence these patterns, leading to variations in cellular function and overall aging.
Measuring Biological Age with Epigenetic Clocks
Scientists leverage these changing DNA methylation patterns to develop tools known as “epigenetic clocks.” These clocks are built by analyzing methylation data from thousands of individuals across various ages and tissue types, identifying specific methylation sites that consistently change with chronological age. By examining the methylation status of these particular sites, an algorithm can estimate a person’s biological age.
A significant advancement in this field came from Dr. Steve Horvath, who pioneered one of the first pan-tissue epigenetic clocks capable of estimating age across virtually all human tissues. His clock uses the methylation levels of 353 specific DNA sites to calculate a biological age. This calculated biological age can be either older or younger than an individual’s chronological age, providing a more refined measure of their body’s actual state of aging. The difference between one’s biological age and chronological age is often referred to as “age acceleration,” indicating whether an individual is aging faster or slower than expected. These epigenetic clocks have shown remarkable accuracy, in some cases even predicting mortality better than chronological age alone.
Factors That Influence the Epigenetic Clock
The pace of our epigenetic clock is influenced by a variety of lifestyle and environmental factors.
Diet
What we consume plays a substantial role. Unhealthy diets rich in processed foods can negatively impact epigenetic marks. Conversely, diets common in long-lived populations, characterized by unprocessed foods like raw vegetables and fruits, are associated with more favorable epigenetic health. Macronutrients, micronutrients, and fasting can also affect gene function through epigenetic changes.
Physical Activity
Regular exercise and even mild environmental stressors, such as temperature fluctuations, may enhance cellular resilience and contribute to a slower epigenetic clock.
Chronic Stress
Chronic psychological stress can disrupt DNA methylation patterns and accelerate biological aging. Studies have linked early-life adverse experiences, such as childhood abuse and neglect, to accelerated epigenetic aging later in life. Managing stress through practices like meditation and breathwork can reduce cortisol levels, which may positively impact stress-related gene expression.
Sleep
Insufficient sleep can contribute to unhealthy epigenetic patterns by affecting gene function. Ensuring adequate and restorative sleep is part of a healthy lifestyle that can help maintain epigenetic integrity.
Environmental Toxins
Exposure to various toxins from our environment also impacts the epigenetic clock. Substances like tobacco, alcohol, heavy metals, plastics, and pesticides can induce detrimental epigenetic alterations. Reducing exposure to these harmful agents can help preserve epigenetic health and potentially slow down biological aging.
Health Implications of Epigenetic Age
The biological age determined by epigenetic clocks holds significant implications for an individual’s health trajectory. An accelerated epigenetic age, where one’s biological age is greater than their chronological age, is linked to an elevated risk of developing various age-related diseases. This measure acts as a powerful predictor of healthspan, which refers to the number of years an individual remains in good health, and overall longevity.
Accelerated epigenetic aging is associated with a higher risk of cardiovascular disease, including increased body mass index, elevated triglycerides, lower high-density lipoprotein (HDL) cholesterol, and hypertension, as well as a higher prevalence of cardiovascular events. It has also been linked to the incidence and mortality of several cancers, including breast cancer. Unhealthy epigenetic patterns are connected to an increased risk of neurodegenerative conditions like Alzheimer’s and Parkinson’s diseases. For instance, a five-year increase in DNA methylation age has been associated with a 16% higher mortality risk, even when accounting for chronological age and other health parameters.