The Hallmarks of Aging: Why We Age at the Cellular Level

What are the hallmarks of aging?

Aging can feel like a single, mysterious slide — but biologists have spent decades taking it apart into understandable pieces. In 2013, a landmark paper titled "The Hallmarks of Aging" in the journal Cell proposed a shared vocabulary for the field. Authored by Carlos López-Otín and colleagues, it identified nine cellular and molecular processes that together drive how organisms age. A decade later, in 2023, the same group published an update expanding the list to twelve.

Think of the hallmarks as the "why" behind the visible signs of getting older. They describe what is happening inside your cells and tissues — long before you notice slower recovery, less energy, or changes in strength. Importantly, no single hallmark acts alone. They feed into one another, which is exactly why aging is so complex and why there is no single "switch" to flip.

The twelve hallmarks at a glance

Here is a plain-language map of the hallmarks described in the 2013 framework and its 2023 expansion. Each one is an active area of research.

Hallmark	What it means in plain language
Genomic instability	DNA accumulates damage over time, and repair systems become less reliable.
Telomere attrition	Protective caps on the ends of chromosomes shorten with each cell division.
Epigenetic alterations	The chemical "tags" that control which genes are switched on or off drift with age.
Loss of proteostasis	The cell's system for folding and clearing proteins becomes less efficient.
Disabled macroautophagy	Autophagy — the cell's clean-up and recycling process — slows down.
Deregulated nutrient sensing	Pathways that gauge energy and nutrient availability lose their fine tuning.
Mitochondrial dysfunction	The cell's energy-producing organelles become less efficient and less well-maintained.
Cellular senescence	Damaged cells stop dividing but linger, releasing inflammatory signals.
Stem cell exhaustion	The reserves that regenerate tissues become depleted over time.
Altered intercellular communication	Cells "talk" to each other differently, often with more low-grade inflammation.
Chronic inflammation	A persistent, low-level inflammatory tone ("inflammaging") builds across tissues.
Dysbiosis	The balance of microbes in the gut and elsewhere shifts with age.

The first four were originally grouped as "primary" hallmarks (the sources of damage), followed by "antagonistic" hallmarks (responses that can turn harmful) and "integrative" hallmarks (the downstream consequences you feel). The 2023 update added disabled macroautophagy, chronic inflammation, and dysbiosis to reflect newer evidence.

A closer look at a few key hallmarks

Cellular senescence is a good example of how a protective process can become a problem. When a cell is too damaged to safely divide, it can enter senescence — a kind of retirement that stops it from becoming cancerous. Helpful in the short term, but as these "zombie" cells accumulate, they secrete signals that promote inflammation in surrounding tissue.

Loss of proteostasis and disabled autophagy are about housekeeping. Cells constantly build proteins and must fold them correctly and dispose of damaged ones. When these quality-control systems slow, misfolded proteins and cellular debris build up — a theme that appears across many age-related changes.

Mitochondrial dysfunction and the role of mitophagy

Mitochondria are often called the "powerhouses" of the cell because they generate most of the energy (ATP) your cells run on. Muscle, heart, and brain tissue are especially energy-hungry, which is why mitochondrial health draws so much attention in aging research. As a hallmark, mitochondrial dysfunction refers to the tendency of mitochondria to become less efficient and less well-maintained over time. You can read more about the signs of poor mitochondrial health and how to support mitochondrial function naturally in our related guides.

One reason mitochondria lose efficiency is that the cell's system for recycling worn-out mitochondria — a specialized form of autophagy called mitophagy — tends to decline with age. Mitophagy is essentially quality control: it tags damaged mitochondria for removal so that healthier ones can take their place. If you want the deep dive, see our explainer on what mitophagy is.

This is where Urolithin A enters the conversation. Urolithin A is a compound your gut microbiome can produce from ellagitannins found in foods like pomegranates, walnuts, and certain berries — though many people don't produce meaningful amounts on their own. In a randomized clinical trial published in Nature Metabolism (2019), Urolithin A was shown to influence mitochondrial and cellular health markers in healthy older adults. A more recent trial in Nature Aging (2025) continued to examine its effects in humans. Across this research, Urolithin A has been studied for supporting mitophagy — tying it specifically to the mitochondrial-dysfunction hallmark.

To be clear about the science: Urolithin A is studied in relation to one hallmark — mitochondrial dysfunction, via mitophagy. It is not a solution to aging as a whole, and there is no human evidence that it, or any supplement, extends lifespan. If you're curious about the research, our overview of Urolithin A walks through it in more detail. For a convenient dietary source, some people choose a SOMA Urolithin A gummy — but a supplement is one small piece of a much bigger picture, and you should talk with your healthcare provider before starting anything new.

What you can actually do to support healthy cellular aging

The good news is that the most powerful, best-supported tools are things you already have access to. None of them "stop" aging, but they support the cellular processes described above.

• Move your body regularly. Exercise — especially a mix of resistance training and aerobic activity — is one of the most robust ways to support mitochondrial health and overall cellular function.
• Prioritize sleep. Quality sleep supports the brain's and body's repair and clean-up processes, including autophagy.
• Eat a whole-food, plant-forward diet. Colorful plants supply the polyphenols and fiber that support your microbiome — relevant to the dysbiosis hallmark — and provide the raw materials your body uses to make compounds like Urolithin A.
• Manage stress and stay connected. Chronic stress feeds into inflammation, one of the integrative hallmarks.
• Don't smoke and limit alcohol. Both accelerate several forms of cellular damage.

Supplements can play a supporting role for specific, well-defined purposes — but they work best on top of these fundamentals, not in place of them. Always consult a qualified healthcare provider before making changes, particularly if you take medications or have a health condition.

Frequently asked questions

Are there 9 or 12 hallmarks of aging?

Both numbers are correct depending on the timeframe. The original 2013 Cell paper described nine hallmarks. The 2023 update by the same research group expanded the framework to twelve, adding disabled macroautophagy, chronic inflammation, and dysbiosis based on newer evidence.

Can the hallmarks of aging be reversed?

The hallmarks are a research framework for understanding aging, not a checklist that can be "reversed." Scientists study ways to slow or influence individual hallmarks, but aging is a normal biological process. No supplement or intervention has been shown to reverse aging or extend human lifespan.

How does Urolithin A relate to the hallmarks of aging?

Urolithin A is studied in connection with one specific hallmark: mitochondrial dysfunction. Human trials have examined its role in supporting mitophagy, the process that recycles aging mitochondria. It is not linked to the other hallmarks, and it is not a treatment for aging.

What is the difference between autophagy and mitophagy?

Autophagy is the cell's general recycling and clean-up process for worn-out components. Mitophagy is a specialized form of autophagy focused specifically on removing damaged mitochondria so healthier ones can replace them. Both tend to decline with age.

What is the single best thing I can do to support healthy aging?

There's no single magic lever, but regular physical activity — especially combining strength and aerobic exercise — is among the most consistently supported habits for cellular and mitochondrial health. Pair it with good sleep and a whole-food diet for the biggest impact, and discuss your plan with your healthcare provider.