Cycloastragenol — The Telomerase Activator
Cycloastragenol is a plant-derived compound best known as the active ingredient in the commercial supplement TA-65, which has been shown to activate the enzyme telomerase. By potentially slowing or reversing telomere shortening, it targets a primary hallmark of aging, aiming to preserve cellular function and delay senescence.
Mechanism of Action
Cycloastragenol is a triterpenoid saponin derived from Astragalus membranaceus that acts as a small-molecule telomerase activator. It is thought to transiently upregulate the expression and activity of telomerase reverse transcriptase (TERT), the catalytic subunit of the telomerase enzyme. By enhancing telomerase activity, cycloastragenol helps maintain telomere length, delaying cellular senescence and apoptosis in highly proliferative cells. It may also exert antioxidant and anti-inflammatory effects through the Nrf2 pathway.
Human Trial Evidence
A 2016 randomized, double-blind, placebo-controlled trial of TA-65 (a cycloastragenol extract) over one year showed a modest but significant lengthening of telomeres in cytomegalovirus-positive subjects compared to placebo. Other small trials have reported improvements in metabolic markers and reductions in senescent immune cells, though large-scale, long-term human longevity trials are lacking.
Dosing Protocol
Typical dosing for TA-65 (cycloastragenol) in clinical trials and commercial supplements ranges from 8 to 50 mg per day (often expressed as 250 to 1,000 'units'). It is typically taken orally once daily. Optimal dosing for longevity remains unestablished.
Safety & Contraindications
Cycloastragenol is generally well tolerated in short-term studies, with no severe adverse events reported at standard doses. However, because telomerase activation is a mechanism utilized by many cancers to achieve cellular immortality, there is theoretical concern regarding its long-term use, particularly in individuals with an active malignancy or high cancer risk. Long-term safety data in humans are currently insufficient.