Two caveats govern every page on this site. (1) Telomere length is a contested aging biomarker — it is measured differently by different methods, varies between tissues, and "longer" is not straightforwardly "healthier"; changing a telomere-length or telomerase-activity number in a trial is not the same as slowing human aging. (2) Activating telomerase is not risk-free — telomerase is silenced in most somatic cells and reactivated in most cancers, so its activation raises an unresolved cancer-risk question. Tellingly, the only FDA-approved telomerase drug — imetelstat (RYTELO, 2024) — inhibits telomerase to treat cancer (lower-risk MDS), the opposite direction from the anti-aging "activation" narrative.
○ Evidence tier 3 — Human RCT — telomere-length / telomerase-activity biomarker endpoint

Record

DesignRandomized, double-blind, placebo-controlled trial (telomere-length biomarker)
N117
DOI10.1089/rej.2015.1793
Citation statusdoi verified via Crossref 2026-07-12 (Rejuvenation Res 2016;19(6):478-484, Salvador et al., 'A Natural Product Telomerase Activator Lengthens Telomeres in Humans: A Randomized, Double Blind, and Placebo Controlled Study'). COMMERCIAL COI: authors affiliated with T.A. Sciences, Inc.; C.B. Harley listed as consultant/co-inventor. PMID/NCT not separately fetched (DOI is the confirmed primary identifier).

Five-qualifier claim

Species / population117 relatively healthy cytomegalovirus-positive adults aged 53–87 (randomized, double-blind, placebo-controlled).
Exposure, route, scheduleOral TA-65, low dose (250 U/day) or high dose (1000 U/day), for 12 months.
Comparator / durationPlacebo-controlled, double-blind, randomized; 1-year duration.
Endpoint / numeric resultLow-dose TA-65 significantly increased median telomere length (+530 ± 180 bp over 12 months, p=0.005) while placebo lost length (−290 ± 100 bp, p=0.01). The high dose (1000 U) showed only a non-significant trend.
What it did NOT establishTelomere length is a contested biomarker, not a clinical or lifespan outcome. The unusual dose-response (low dose worked, high dose did not) and the authors' commercial interest in TA-65 both temper interpretation. No healthy-aging or lifespan benefit is established.

Primary reference

https://doi.org/10.1089/rej.2015.1793

Exact identifier confirmed against the primary record via Crossref/ClinicalTrials.gov where stated in the citation status; anything marked needs_primary_fulltext is not yet confirmed.