Geroprotectors: Supplements That Slow the Biology…

A geroprotector is a compound that slows the biological processes of aging itself—as distinct from treating a specific age-related disease. The concept is relatively new in formal scientific terminology but ancient in practice: humans have sought anti-aging interventions throughout history. What is new is a rigorous mechanistic framework for evaluating whether a compound targets fundamental aging biology versus simply treating downstream symptoms. The hallmarks of aging framework—genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication—provides the modern standard.

Why Geroprotectors Matter

Treating individual diseases one at a time is less efficient than targeting their shared upstream causes. A person who avoids heart disease through statins still dies of cancer or dementia at similar ages. But a true geroprotector—one that slows the underlying biology of aging—delays multiple diseases simultaneously. This is sometimes called the "geroscience hypothesis," and the TAME trial testing metformin is the most significant attempt to prove it in humans.

Metformin

Metformin is the most extensively studied potential geroprotector. Epidemiological data shows diabetics on metformin outlive non-diabetics not on the drug. Mechanistically, metformin activates AMPK, inhibits mTORC1, reduces mitochondrial ROS, and modulates the gut microbiome in ways associated with metabolic health. The TAME trial will determine whether these effects translate to delayed aging in non-diabetics.

Rapamycin

Rapamycin extends lifespan in every organism tested where it has been tried, including mice started on it at middle age. It inhibits mTORC1, inducing autophagy and reducing protein synthesis. At low intermittent doses (1-6 mg/week), some physicians prescribe it off-label for longevity. Natural partial mimetics (berberine, EGCG, curcumin, AKG) provide weaker but accessible alternatives.

NAD+ Precursors

NMN and NR address a fundamental aspect of aging biology—declining NAD+—that affects sirtuins, DNA repair, mitochondrial function, and circadian rhythms. They are among the best-characterized geroprotector candidates with robust human pharmacokinetic data and emerging functional evidence.

Senolytics

Fisetin, quercetin, and dasatinib-quercetin address cellular senescence—one of the most established hallmarks of aging. Reducing senescent cell burden reduces the SASP, decreases inflammation, and improves tissue function in multiple organ systems.

Spermidine

Spermidine addresses proteostasis decline and aging through autophagy induction. Population data links dietary spermidine to longevity, and small human trials support cognitive and cardiovascular benefits. Doses of 1-10 mg/day represent a low-risk, evidence-consistent intervention.

Alpha-Ketoglutarate

AKG targets epigenetic aging through TET enzyme cofactor support and mTOR inhibition. A human RCT showing reduced biological age makes it one of the few supplements with direct epigenetic clock data.

Lithium

Lithium at low doses (far below psychiatric doses) extends lifespan in C. elegans, Drosophila, and has been associated with reduced dementia rates in population studies correlating regional lithium levels in drinking water with cognitive outcomes. The mechanism involves GSK-3beta inhibition, which supports autophagy and reduces tau phosphorylation. Low-dose lithium orotate (1-5 mg/day) is available as a supplement.

FAQ

What makes a supplement a geroprotector versus just an antioxidant? Antioxidants scavenge free radicals—a downstream symptom of aging. Geroprotectors address upstream mechanisms: NAD+ decline, mTOR overactivation, senescence accumulation, epigenetic drift. A compound can have antioxidant properties (like quercetin) and also be a geroprotector if it addresses fundamental aging biology, but simply being an antioxidant does not qualify a compound as a geroprotector.

How do I know if a geroprotector is working in my body? Biological age clocks (epigenetic, methylation-based) are the most direct measure. Blood biomarkers including inflammatory cytokines, insulin sensitivity, NAD+ levels, and senescence markers (p16 in T-cells) serve as proxies. Functional measures—grip strength, VO2 max, cognitive scores—are the most clinically meaningful endpoints.

Is there a recommended geroprotector stack? The longevity science community has not standardized a protocol. A common evidence-based stack includes NAD+ precursor (NMN or NR), berberine or metformin, resveratrol or pterostilbene, spermidine, and periodic senolytic pulses with fisetin and quercetin. This covers multiple hallmarks of aging with overlapping but not fully redundant mechanisms.

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Geroprotectors: Supplements That Slow the Biology of Aging