The Science of Aging Explained: The 12 Hallmarks of Aging

Body aging consists of a series of interconnected processes. Recent biomedical research has identified the "Hallmarks of Aging"—the biological mechanisms that drive the aging process at the cellular level.

Key finding: Biomedical research has identified twelve fundamental mechanisms underlying cellular aging—from epigenetic alterations to microbiome dysbiosis (López-Otín et al., 2013).

Table of Contents

1. Epigenetic Alterations
2. Loss of Proteostasis
3. Impaired Autophagy
4. Deregulated Nutrient Sensing
5. Mitochondrial Dysfunction
6. Cellular Senescence
7. Stem Cell Exhaustion
8. Altered Intercellular Communication
9. Chronic Inflammation
10. Microbiome Dysbiosis
11. Genomic Instability
12. Telomere Shortening
13. Overview of the 12 Hallmarks
14. References

Epigenetic Alterations

Our genome consists of long DNA strands wrapped around protein spools called histones. These histones are equipped with chemical modifications that regulate whether genes are switched on or off. Together, these regulatory mechanisms form the epigenome. As we age, the epigenome changes, potentially impairing the precise coordination of gene activity. One of the best-studied groups of enzymes influencing the epigenome are the sirtuins. Nutrition, medications, and lifestyle modifications can also alter the epigenome.

Learn more about these regulatory mechanisms in our article on Sirtuins, AMPK and mTOR.

Loss of Proteostasis

The primary function of genes is to produce proteins. These proteins regulate virtually all chemical reactions within the cell and must be folded into precise three-dimensional structures to function correctly. With age, epigenetic damage increasingly leads to protein misfolding, causing proteins to lose their normal function. The process responsible for maintaining proteins in their correct structure is known as proteostasis.

Impaired Autophagy

Autophagy is a cellular process that breaks down damaged or dysfunctional cellular components and recycles their building blocks—essentially serving as the cell's recycling system. This function is vital for maintaining cellular health and preventing the accumulation of toxic waste. As we age, autophagy declines, allowing damaged proteins and organelles to accumulate. This contributes to the development of age-related diseases such as neurodegenerative disorders and cancer.

Deregulated Nutrient Sensing

When nutrients are abundant, cells prioritize growth and proliferation. When nutrients become scarce, the body shifts its focus toward maintenance and repair. Research has investigated strategies such as calorie restriction and certain medications that mimic nutrient deprivation. In animal studies, these approaches have improved both healthspan and lifespan.

Mitochondrial Dysfunction

Mitochondria are the "powerhouses of the cell," but they also generate free radicals, known as reactive oxygen species (ROS), which can damage cells. A more recent concept suggests that these reactive oxygen species may serve an important signaling function by triggering cellular stress responses that enhance maintenance and repair mechanisms in cells, tissues, and organs (López-Otín et al., 2013).

Cellular Senescence

Cellular senescence is a process in which cells permanently stop dividing. With advancing age, these senescent cells accumulate and release harmful signaling molecules into their surrounding environment. One major cause of cellular senescence is the shortening of telomeres—DNA sequences located at the ends of chromosomes that are essential for chromosome stability and many biological processes. Telomere shortening is closely associated with aging.

Recent studies in genetically modified mice, in which researchers selectively eliminated many senescent cells, have demonstrated significant health benefits, including increased lifespan. Current research is focused on developing drugs that selectively target and remove these senescent cells.

Good to know: The targeted elimination of senescent cells is considered one of the most promising anti-aging strategies in modern research. Learn more in our article on Anti-Aging: Promising Developments.

Stem Cell Exhaustion

The body's ability to regenerate tissues and organs depends on healthy stem cells. These cells can differentiate into various cell types and replicate when needed. As we age, stem cell reserves become depleted, and aging stem cells gradually lose their regenerative capacity.

Altered Intercellular Communication

Communication between cells and tissues is essential for maintaining normal bodily functions. Hormones, for example, serve as important signaling molecules. Age-related chronic inflammation—likely resulting in part from senescent cells—can significantly impair or disrupt this communication. Restoring proper intercellular communication may improve health, for example by reducing chronic age-related inflammation.

Chronic Inflammation

Chronic inflammation is another hallmark of aging, characterized by persistent low-grade inflammatory activity throughout the body. Unlike acute inflammation, which provides a rapid and effective defense against threats such as infections, chronic inflammation remains active over long periods. It is often triggered by age-related factors including senescent cells, DNA damage, and dysfunctional mitochondria. These inflammatory processes can impair cellular and tissue function and increase the risk of age-related diseases such as Alzheimer's disease, diabetes, and cardiovascular disease.

Microbiome Dysbiosis

The gut microbiome plays a crucial role in human health and the aging process. As we grow older, the composition of the intestinal microbiota changes—a process known as dysbiosis. These changes may weaken the immune system, promote chronic inflammation, and impair nutrient absorption. Dysbiosis has also been associated with age-related diseases such as diabetes, cardiovascular disease, and neurodegenerative disorders.

Learn how nutrition can specifically support gut health in our article Nutrition for Longevity and Gut Diversity.

Genomic Instability

The genome—our complete genetic material—is responsible for the proper functioning of the body. External and internal stressors, such as pollution and free radicals, continuously damage DNA within our cells. Cellular repair mechanisms normally detect and correct this damage. However, with increasing age, DNA damage accumulates faster than repair systems can keep up. Cancer is one possible consequence of unrepaired DNA damage. Organisms with impaired DNA repair mechanisms exhibit signs of accelerated aging.

Telomere Shortening

Telomere shortening is a specific form of genomic instability. Telomeres are repetitive DNA sequences that protect the ends of chromosomes and prevent them from being mistaken for broken DNA strands. They are considered key determinants of biological aging. Telomeres shorten naturally with each cell division and through DNA-damaging processes. Once they reach a critically short length, the cell permanently loses its ability to divide. Telomerase, an enzyme located in the cell nucleus, can prevent telomere shortening and may even restore telomere length.

Your biological age—including telomere length and DNA methylation profile—can now be measured directly using the bioAge Test by neotes. Learn how you can actively influence your epigenetic clock in our article Improving Biological Age: Resetting the Epigenetic Clock.

Overview of the 12 Hallmarks

References

1. López-Otín C, Blasco MA, Partridge L, Serrano M. The Hallmarks of Aging. Cell. 2013 Jun 6;153(6):1194–1217. doi: 10.1016/j.cell.2013.05.039. ncbi.nlm.nih.gov/pmc/articles/PMC3836174