Cycloastragenol

The human evidence is one randomised telomere trial, one independent randomised trial that did not measure telomeres, one small eye pilot, and two uncontrolled observational cohorts.

⚠️ The randomised telomere trial is the one everything rests on, and it has five problems visible in its own text ^[3]. The dose response inverts: 8 mg gained an estimated 530 base pairs at a year while 32 mg was null at every timepoint, and the authors write that they do not know why the high-dose group behaved randomly. The placebo group lost 290 base pairs per year against an expected 50 to 150, and against the study's own cross-sectional estimate of 50, so much of the separation comes from an anomalous control arm. The authors concede their assay reads longer than other methods. The raw observed change was 0.24 kilobases, not the headline 0.53, which is a model-estimated interaction term. And two authors were employed by the seller, the patent inventor was a consultant, and the trial physician ran an anti-ageing clinic.

The only independent randomised study found improvements in cholesterol, waist circumference and an inflammatory marker in metabolic syndrome ^[5]. ⚠️ It did not measure telomere length or telomerase at all, so it is evidence about metabolic markers rather than telomere biology.

The two observational cohorts are uncontrolled, combine the compound with a supplement pack and physician counselling, and lost up to 72 percent of participants ^[4].

⚠️ The seller's own 500-person randomised trial, registered in 2016 and due to complete in 2017, has never reported. A separate trial of cycloastragenol itself in Alzheimer's disease completed in 2018 and has posted no results.

The available safety data is reassuring in its narrow way and much thinner than its reputation suggests.

In mice, dietary supplementation improved glucose tolerance, bone and skin measures without significantly increasing overall cancer incidence ^[2]. The rodent no-observed-adverse-effect level is above 150 mg per kilogram per day. In the one randomised human trial, 97 people took it for a year with no clinically significant changes in liver, kidney or metabolic markers ^[3].

Several laboratory findings argue against the obvious worry that a telomerase activator promotes cancer: it did not raise telomerase in a tumour cell line, did not change the rate of viral transformation of normal cells, and did not immortalise primary immune cells, which still senesced after about thirty divisions ^[1].

⚠️ One frequently quoted safety claim should be read carefully. A paper reports that over five years and roughly 7,000 person-years of use, no adverse events were attributed to the product by physicians licensed to sell it. The people judging causality were the people selling it. That is not pharmacovigilance.

There is no controlled long-term safety dataset and no human cancer-incidence data of any kind.

Astragalus has been used in Chinese medicine for centuries, and interest in its triterpenoids sharpened around 2000 when a screen of traditional-medicine extracts at Geron, a telomere biology company, identified compounds that raised telomerase in cultured cells. The resulting patent, filed in 2003, names cycloastragenol and astragaloside IV explicitly. The compound entered public awareness not as a drug but as TA-65, a supplement sold by a company spun out of that programme, and its scientific record has been shaped by that route ever since: the key papers share authors with the patent and the seller, the definitive trial was never published, and the compound has never been developed on a drug track. It remains the most credible molecule in a field where most claims have none.