Why We Age: The 12 Hallmarks of Aging
In 2013, a landmark paper in Cell identified 9 hallmarks of aging. By 2023, the list expanded to 12. These hallmarks represent the biological processes that drive aging — and the targets that longevity science is trying to address.
What Are the Hallmarks?
The hallmarks framework organizes the complex biology of aging into discrete, interconnected processes. Think of them as the "categories of damage" that accumulate over time. Some are causes (primary hallmarks), some are responses to damage (antagonistic hallmarks), and some are the downstream consequences (integrative hallmarks).
Understanding which hallmark a product targets helps you evaluate whether its mechanism is relevant to your goals — and whether the science supports the claim.
Primary Hallmarks (Causes of Damage)
These are the root causes that initiate the aging process.
1. Genomic Instability
DNA accumulates damage over time from radiation, oxidative stress, and replication errors. Repair mechanisms (like PARP enzymes, which require NAD+) become less efficient with age. This is one reason NAD+ precursors like NMN are of interest — they fuel the DNA repair machinery.
Targetable with: NAD+ precursors, DNA repair support
2. Telomere Attrition
Telomeres — protective caps on chromosome ends — shorten with each cell division. When they get too short, cells enter senescence or die. Telomere length correlates with biological age, though whether it's a cause or marker of aging is debated. Omega-3 fatty acids have been associated with slower telomere shortening in observational studies.
Targetable with: Omega-3s (observational evidence), exercise, stress reduction
3. Epigenetic Alterations
DNA methylation patterns, histone modifications, and chromatin structure change with age, altering gene expression in harmful ways. This is the basis for epigenetic age testing — and the core of David Sinclair's "information theory of aging," which posits that aging is fundamentally a loss of epigenetic information. Sirtuins (activated by NAD+) help maintain epigenetic stability.
Targetable with: NAD+ precursors, lifestyle interventions (diet, exercise, sleep)
4. Loss of Proteostasis
The cell's ability to maintain properly folded, functional proteins declines. Misfolded proteins accumulate (think: amyloid in Alzheimer's). Autophagy — the cell's recycling system — is a key proteostasis mechanism. Spermidine is one of the few compounds that reliably induces autophagy.
Targetable with: Spermidine, fasting, exercise
Antagonistic Hallmarks (Responses to Damage)
Initially protective, these become harmful when chronic or excessive.
5. Deregulated Nutrient Sensing
Pathways like mTOR, AMPK, insulin/IGF-1, and sirtuins regulate how cells respond to nutrients. With age, these become dysregulated — cells behave as if nutrients are always abundant, promoting growth over repair. This is why caloric restriction and fasting extend lifespan in animal models: they shift the balance toward repair pathways.
Targetable with: Intermittent fasting, exercise, sulforaphane (Nrf2), spermidine
6. Mitochondrial Dysfunction
Mitochondria — the cell's powerhouses — become less efficient at producing ATP and generate more damaging reactive oxygen species (ROS). This is one of the most directly targetable hallmarks. See our deep dive on Mitochondria, ATP, and Aging. Products targeting this hallmark include CoQ10, Urolithin A, Creatine, and Red Light Therapy.
Targetable with: CoQ10, Urolithin A, PQQ, Creatine, Red Light Therapy, exercise (especially HIIT)
7. Cellular Senescence
Damaged cells that stop dividing but refuse to die become "zombie cells" — they secrete inflammatory factors (the SASP — senescence-associated secretory phenotype) that damage surrounding tissue. Clearing these cells with senolytics is one of the most exciting areas in aging research. Fisetin is the most studied natural senolytic, though human evidence is still emerging.
Targetable with: Fisetin (emerging), dasatinib+quercetin (prescription/research)
Integrative Hallmarks (Consequences)
The downstream effects when primary and antagonistic hallmarks aren't resolved.
8. Stem Cell Exhaustion
The body's regenerative capacity declines as stem cell populations shrink and lose function. This limits tissue repair and immune system renewal. Currently, there are no well-validated consumer products that directly address stem cell exhaustion — this remains a frontier of clinical research.
9. Altered Intercellular Communication
Aging changes how cells communicate, leading to chronic low-grade inflammation ("inflammaging"). This drives virtually every age-related disease. Anti-inflammatory interventions like omega-3s and high-polyphenol olive oil target this hallmark directly.
The 2023 Additions
The 2023 update in Cell added three new hallmarks:
10. Disabled Macroautophagy
Previously part of "loss of proteostasis," autophagy got its own hallmark — recognizing its central importance. The decline in cellular recycling with age is now considered a primary driver, not just a symptom.
11. Chronic Inflammation
"Inflammaging" was elevated from a sub-process to a full hallmark. Chronic, sterile inflammation underlies cardiovascular disease, neurodegeneration, cancer, and metabolic syndrome.
12. Dysbiosis
The gut microbiome changes with age in ways that promote inflammation and reduce beneficial metabolite production (like the conversion of ellagitannins to urolithin A). Microbiome health is increasingly recognized as central to healthy aging.
Which Hallmarks Can You Actually Target?
Not all hallmarks are equally targetable with current consumer products. Here's an honest assessment:
| Hallmark | Consumer Targetability | Best Intervention |
|---|---|---|
| Mitochondrial Dysfunction | High | Exercise, CoQ10, Urolithin A, Red Light |
| Chronic Inflammation | High | Omega-3, EVOO, exercise, sleep |
| Disabled Macroautophagy | Moderate | Fasting, spermidine, exercise |
| Epigenetic Alterations | Moderate | Lifestyle (diet, exercise, sleep), NAD+ precursors |
| Cellular Senescence | Moderate | Fisetin (emerging), exercise |
| Nutrient Sensing | Moderate | Fasting, exercise (free!) |
| Dysbiosis | Moderate | Diet diversity, fermented foods, fiber |
| Genomic Instability | Low | NAD+ precursors (indirect), avoid mutagens |
| Telomere Attrition | Low | Exercise, stress management |
| Stem Cell Exhaustion | Low | No validated consumer interventions yet |
The Honest Truth
Notice that "exercise" appears in almost every row. Regular physical activity — particularly a combination of resistance training and HIIT — remains the single most powerful anti-aging intervention known to science. It targets at least 8 of the 12 hallmarks simultaneously. No supplement comes close. Supplements are, at best, a complement to the basics: exercise, sleep, stress management, and a whole-food diet.