The core challenge of geroscience is measuring aging itself — finding “aging clocks” that precisely reflect biological aging rates, both for scientific research (evaluating intervention effects) and precision health (personalized anti-aging recommendations). In 2013, Steve Horvath’s DNA methylation-based “Horvath Clock” was a milestone in aging biomarker research.
## Major Aging Biomarkers
**DNA Methylation Clocks (Epigenetic Clocks)**: methylation levels at specific CpG sites across the genome change predictably with age. Horvath (2013), Hannum (2013), PhenoAge (2018), and GrimAge (2019) are the major versions; the latter has the strongest all-cause mortality prediction. Commercial testing products: TruAge, Elysium, and domestic Chinese companies offer methylation age testing at various precision levels, from hundreds to thousands of RMB.
**Telomere Length**: the protective caps at chromosome ends shorten with each cell division until reaching the Hayflick limit and cellular senescence. Short telomeres are associated with various age-related diseases, but telomere length testing has high intra-individual variability (large differences across tissues and measurement methods), limiting reliability as an individual biomarker.
**Proteomic Clock**: in 2023, Stanford’s Snyder team and UK Biobank research independently found that the plasma proteome (~3,000 proteins’ dynamic changes) shows three distinct aging acceleration inflection points at ages 34, 60, and 78 — providing direct evidence that “aging is a nonlinear process.”
## Current Evidence for Anti-Aging Interventions
NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) are currently the most popular anti-aging supplements, raising NAD+ levels to activate Sirtuin proteins. Animal (mouse) research results are positive, but human RCT evidence remains limited with smaller effect sizes than animal experiments. Metformin’s anti-aging effects (TAME trial — Targeting Aging with Metformin) are under large-scale validation (ongoing as of 2024). Rapamycin has the strongest longevity evidence in animal experiments to date, but optimal human dosing and long-term safety remain unestablished.
See [Digital Health Overview](https://sunqi.org/digital-health-overview-en/) and [David Sinclair “Lifespan”](https://lifespanbook.com/).
