Biological Age: A Key to Staying Healthy?

Living longer is meaningful only when those additional years are spent in good health. Ideally, healthspan—the period of life free from major disease and disability—should be as close as possible to lifespan.

Biological age is intended to describe how old the body and its cells appear from a functional and molecular perspective. Unlike chronological age, it may provide information about the pace of aging and current cellular health.

Can DNA indicate biological age?

Biological age can be estimated by analyzing DNA methylation patterns. DNA methylation is an epigenetic modification that influences gene activity without changing the underlying DNA sequence.

Specific methylation patterns are associated with chronological age and selected health outcomes. Statistical models known as epigenetic clocks use these patterns to estimate biological age.

Studies of exceptionally long-lived individuals, including supercentenarians, have found that some of them show younger epigenetic age estimates than their chronological age.

Which factors influence biological age?

Genetics plays an important role, but lifestyle and environmental factors also contribute substantially. Relevant influences include:

• Nutrition
• Sleep
• Exercise and daily movement
• Exposure to environmental pollutants
• Smoking and alcohol
• Psychosocial stress
• Social relationships

DNA damage and genomic instability

One hallmark of aging is increasing genomic instability. DNA is continuously exposed to radiation, chemicals, metabolic by-products and oxidative stress. Cells possess repair mechanisms, but these systems may become less efficient with age.

Persistent DNA damage may interfere with normal cellular function and contribute to the development of age-related disease.

Telomere length

Telomeres protect the ends of chromosomes and are often compared with the plastic caps on shoelaces. They become shorter during repeated cell division.

When telomeres become critically short, cells may stop dividing or enter cellular senescence. Telomere length is therefore one of several biomarkers discussed in connection with biological aging. It is not, however, a complete measure of health or lifespan on its own.

The epigenome

The epigenome regulates which genes are active or inactive in response to development, environment and lifestyle. Unlike the inherited DNA sequence, epigenetic patterns can change throughout life.

Exercise, nutrition, pollutants, stress and other factors may influence gene regulation. With age, epigenetic control can become less precise, potentially affecting muscle maintenance, mitochondrial energy production and other cellular processes.

Senescent cells

Senescent cells have permanently stopped dividing but do not immediately disappear. They are sometimes called “zombie cells.” Although senescence can protect against uncontrolled cell growth, the accumulation of senescent cells may contribute to chronic inflammation and tissue dysfunction.

Conclusion

Biological age reflects the interaction of genomic stability, telomeres, epigenetic regulation, metabolism and lifestyle. It is not a single fixed number but an estimate based on selected biomarkers.

Epigenetic testing can provide insight into DNA methylation patterns and may be useful for monitoring long-term lifestyle changes. Results should always be interpreted in context and should not be regarded as a diagnosis or a guaranteed prediction of lifespan.

Sources

• Chen BH et al. DNA methylation-based measures of biological age: meta-analysis predicting time to death. Aging. 2016.
• Gruber HJ et al. Telomeres and age-related diseases. Biomedicines. 2021.
• Benayoun BA, Pollina EA, Brunet A. Epigenetic regulation of ageing. Nature Reviews Molecular Cell Biology. 2015.
• Samarakoon SM et al. Dietary, social and lifestyle determinants of accelerated aging. Ayu. 2011.