Cycloastragenol

Also called CAG, astramembrangenin, TA-65 (related commercial product).

Best grade D across 4 graded outcomes Botanical Last checked Oct 21, 2026

The short answer

From 11 sources

Cycloastragenol is a triterpenoid from Astragalus root. Its human data come from TA-65, a commercial telomerase activator that reviews describe as a cycloastragenol derivative. Small trials reported longer telomeres, better macular function and better cholesterol markers, and a 12-month trial after heart attack missed its primary immune endpoint. None tested hard clinical outcomes, and a review flags a possible tumour-growth concern.

Every graded outcome on this page

4 rows · line = participants

Grade DLeukocyte telomere length over 1 yearTelomeresn 117
Grade DImmune ageing and inflammation after a heart attackImmune ageingn 90
Grade DCardiovascular and inflammation markers in metabolic syndromeCholesteroln 40
Grade DMacular function (microperimetry) in early age-related macular degenerationEye healthn 38

Key facts

Human evidence base: Trials tested TA-65, a commercial derivative; no trial cited here tested pure cycloastragenol by name^7,1
Telomere trial: Low dose (250 U/day) lengthened telomeres over 12 months in 117 adults; the high dose did not differ significantly from placebo¹
Metabolic syndrome: 16 mg/day for 12 weeks raised HDL and lowered TNF-α versus placebo in 40 adults⁴
Animal safety: No adverse effects in rats up to 150 mg/kg/day for 91 days; not mutagenic in bacterial tests⁵
Cancer question: A 2026 review notes telomerase modulation may suppress or, in some contexts, promote tumour growth⁷

What it is

Cycloastragenol is a triterpenoid from Astragalus root, sold as a telomerase-activator supplement.

How it works

Proposed

Cycloastragenol and TA-65 are described as small-molecule telomerase activators; in cell culture, low nanomolar TA-65 levels moderately activated telomerase in skin, connective-tissue and immune cells. Reviews also describe anti-inflammatory signalling effects (NF-κB, Nrf2, NLRP3) from preclinical work, and note that poor bioavailability limits clinical use.^2,6

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Cycloastragenol forms compared

2 forms

Cycloastragenol forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 forms	TA-65 (proprietary Astragalus-derived telomerase activator)	(generic ingredient)
Absorption in people	In pilot pharmacokinetic studies, single 10–50 mg doses reached plasma levels similar to those that activated telomerase in cell culture.²	A 2025 review identifies pharmacokinetic limitations (low bioavailability) as a barrier to clinical use; no human absorption study of generic cycloastragenol is cited here.⁶
GI tolerance	No adverse events were attributed to a program including 10–50 mg/day of TA-65 in its first year of data.²	Rat studies found no adverse effects up to 150 mg/kg/day; human safety data come only from TA-65 trials.⁵
Studied for	Telomere length, immune-cell profile, macular function, metabolic markers	No human trials of the generic ingredient cited here

TA-65 (proprietary Astragalus-derived telomerase activator)
Absorption in people
In pilot pharmacokinetic studies, single 10–50 mg doses reached plasma levels similar to those that activated telomerase in cell culture.²
GI tolerance
No adverse events were attributed to a program including 10–50 mg/day of TA-65 in its first year of data.²
Studied for
Telomere length, immune-cell profile, macular function, metabolic markers
Cycloastragenol (generic ingredient)
Absorption in people
A 2025 review identifies pharmacokinetic limitations (low bioavailability) as a barrier to clinical use; no human absorption study of generic cycloastragenol is cited here.⁶
GI tolerance
Rat studies found no adverse effects up to 150 mg/kg/day; human safety data come only from TA-65 trials.⁵
Studied for
No human trials of the generic ingredient cited here

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

4 graded outcomes, largest study first

4 graded outcomes: 2 improved, 2 mixed. The largest, a 2016 randomized trial of 117 people on leukocyte telomere length over 1 year, found mixed results.

By sizeTable

1Leukocyte telomere length over 1 year

Mixed · Grade D · RCT, 117 people, 2016

Relatively healthy cytomegalovirus-positive adults aged 53–87

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Leukocyte telomere length over 1 year	Mixed	117	Grade D · RCT, 2016	Relatively healthy cytomegalovirus-positive adults aged 53–87
Immune ageing and inflammation after a heart attack	Mixed	90	Grade D · RCT, 2023	Heart attack patients over 65 (median age 71), UK
Cardiovascular and inflammation markers in metabolic syndrome	Improved	40	Grade D · Crossover RCT, 2018	Adults with metabolic syndrome
Macular function (microperimetry) in early age-related macular degeneration	Improved	38	Grade D · RCT, 2016	Patients with early age-related macular degeneration

Every graded row

4 rows

Form tested

Showing 4 of 4 outcomes. Human trials only.

Grade DLeukocyte telomere length over 1 yearTelomeresMixedRCT
n 117 · 2016

Mixed The low dose increased telomere length by 530 ± 180 bp while the placebo group lost 290 ± 100 bp. The high dose showed only a non-significant trend versus placebo.

Design: RCT, n = 117, 2016
Population: Relatively healthy cytomegalovirus-positive adults aged 53–87
Form: TA-65 (Astragalus-derived telomerase activator)
Dose: 250 U/day (low dose) or 1,000 U/day (high dose)
Duration: 12 months
Source: Reference 1 · PubMed 26950204 (opens PubMed)

Grade DImmune ageing and inflammation after a heart attackImmune ageingMixedRCT
n 90 · 2023

Mixed The primary endpoint, the share of late-stage CD8+ TEMRA T cells, did not differ. Total lymphocytes rose by 285 cells/µl versus placebo, hsCRP was 62% lower (1.1 vs 2.9 mg/L), and adverse events were fewer (130 vs 185).

Design: RCT, n = 90, 2023
Population: Heart attack patients over 65 (median age 71), UK
Form: TA-65 vs placebo
Dose: 16 mg/day
Duration: 12 months
Source: Reference 10 · PubMed 37086366 (opens PubMed)

Grade DCardiovascular and inflammation markers in metabolic syndromeCholesterolImprovedCrossover RCT
n 40 · 2018

Improved Compared with placebo, HDL cholesterol was higher and BMI, waist circumference, LDL/HDL ratio and TNF-α were lower during the TA-65 period.

Design: Crossover RCT, n = 40, 2018
Population: Adults with metabolic syndrome
Form: TA-65 supplement
Dose: 16 mg/day
Duration: 12 weeks per period (3-week washout)
Source: Reference 4 · PubMed 29546832 (opens PubMed)

Grade DMacular function (microperimetry) in early age-related macular degenerationEye healthImprovedRCT
n 38 · 2016

Improved Macular threshold sensitivity improved 0.97 dB versus placebo (p = 0.02), and the share of reduced thresholds fell 8.2% versus placebo (p = 0.04).

Design: RCT, n = 38, 2016
Population: Patients with early age-related macular degeneration
Form: Oral TA-65
Dose: Not stated in the abstract
Duration: 1 year
Source: Reference 3 · PubMed 26869760 (opens PubMed)

Lab research: drug-metabolizing enzymes

1 note

A lab finding, not tested in people.

CYP enzymes (lab study): In human liver microsomes, cycloastragenol inhibited CYP3A4 (IC50 13.40 µM), CYP2E1 (15.00 µM) and CYP2C19 (18.46 µM); the authors suggest a potential for herb-drug interactions.¹¹

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

Telomeres changed, function was not tested

The 1-year trial measured telomere length, a lab marker; it did not report clinical ageing outcomes, and only the lower dose was significant.¹

Few independent trials

Three of the human studies cited here share a co-author, C.B. Harley, who consults for TA-65 maker T.A. Sciences; in the 1-year telomere trial, the clinical investigator was supported by company funding and two authors were company employees.^1,2,3

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from 10–50 mg/day of TA-65 in an open-label health program to 16 mg/day for 12 weeks in metabolic syndrome and for 12 months after a heart attack; the 1-year telomere trial reported 250 or 1,000 units a day, a proprietary measure not converted to mg in the abstract. No trial cited here tested a stated dose of pure cycloastragenol. These are research doses, not recommendations.^1,2,4,10

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Cycloastragenol and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Cycloastragenol.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

3 groups

History of cancer: Telomerase activation may, in some contexts, promote tumour growth according to a 2026 review; no long-term human cancer data exist for these products.⁷
Pregnancy, breastfeeding and children: No reliable data. Trials enrolled adults (53–87 years in the telomere trial). LactMed has no cycloastragenol entry, and its astragalus chapter finds no data on astragalus components in breast milk or on safety in nursing mothers or infants.^1,12
People on prescription medicines: In a 2026 lab study with human liver enzymes, cycloastragenol inhibited CYP3A4, CYP2C19 and CYP2E1, which break down many drugs. This has not been tested in people, so the clinical effect is unknown.¹¹

Safety first

5 notes

Short trials, a theoretical cancer question.

Telomerase and tumours: A 2026 review notes telomerase modulation could suppress tumour progression or, in some contexts, promote tumour growth.⁷
Side effects in trials: In a 12-month placebo-controlled trial in 90 heart attack patients, adverse events were fewer with TA-65 than with placebo (130 vs 185).¹⁰
Animal toxicology: In rats, 91 days at up to 150 mg/kg/day caused no adverse effects; a lab chromosome test was moderately positive at one concentration, likely due to poor solubility, and other genotoxicity tests were negative.⁵
Combination products: A 2-year trial arm combining TA-65 with high-dose resveratrol was stopped at month 5 after LDL cholesterol rose; the authors attribute this probably to the resveratrol.⁸
Legal status: TA-65 is sold as a dietary supplement.¹

How to read the label

What to check on the Supplement Facts panel.

How to read the label

2 checks

TA-65 is not the same as a cycloastragenol label

Human results come from TA-65; a generic cycloastragenol product is not the tested formulation.^1,7

Label dose vs studied dose

Trial doses were 10–50 mg/day of TA-65, or proprietary units; there is no studied dose for generic cycloastragenol.^1,2,4

Have the bottle? Photograph its Supplement Facts panel and see each line, cycloastragenol included, beside the doses and forms the trials used in Label X-Ray.

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

5 answers

Does it lengthen telomeres?

In one 12-month trial the low dose lengthened telomeres versus placebo, but the higher dose did not reach significance.¹

Is there human data on pure cycloastragenol?

No human trial cited here tested pure cycloastragenol by name; its safety data come from rat studies.^5,6

Is it safe?

Trials of up to a year reported no attributed adverse events, but long-term safety is unknown and a review flags a possible tumour-growth concern.^2,7

Does cycloastragenol interact with medications?

No human interaction studies exist. A 2026 lab study found it inhibits three liver enzymes (CYP3A4, CYP2C19 and CYP2E1) that clear many drugs, so an interaction is possible but unproven.¹¹

Is cycloastragenol the same as TA-65?

Reviews describe TA-65 as a commercial derivative of cycloastragenol. Human trials used TA-65, so their results may not apply to generic cycloastragenol.^7,1

Sources

11 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

11 sources

1A Natural Product Telomerase Activator Lengthens Telomeres in Humans: A Randomized, Double Blind, and Placebo Controlled Study.RCT Rejuvenation Res, 2016 · PMID 26950204
2A natural product telomerase activator as part of a health maintenance program.Open-label trial Rejuvenation Res, 2011 · PMID 20822369
3Evaluation of an oral telomerase activator for early age-related macular degeneration - a pilot study.RCT Clin Ophthalmol, 2016 · PMID 26869760
4TA-65, A Telomerase Activator improves Cardiovascular Markers in Patients with Metabolic Syndrome.Crossover RCT Curr Pharm Des, 2018 · PMID 29546832
5Dietary safety of cycloastragenol from Astragalus spp.: subchronic toxicity and genotoxicity studies.Animal study Food Chem Toxicol, 2014 · PMID 24316212
6Cycloastragenol in inflammation-related diseases: mechanisms, pharmacokinetics, and translational prospects.Review Front Pharmacol, 2025 · PMID 41601951
7Astragalus membranaceus Has Potential Anti-Aging and Anticancer Effects on Skin and Bone.Review Biomolecules, 2026 · PMID 42352330
8The proBNPage reduction (PBAR) trial-results of a randomized, double blind, placebo-controlled, pilot study to fine tune an NT-proBNP-based method to assess the effect of anti-aging treatments.RCT Geroscience, 2026 · PMID 40922000
10Activation of telomerase by TA-65 enhances immunity and reduces inflammation post myocardial infarction.RCT Geroscience, 2023 · PMID 37086366
11In vitro investigation of the effect of cycloastragenol (CAG) on the cytochrome P450 enzyme activities.Lab study Arch Biochem Biophys, 2026 · PMID 42107731
12AstragalusDatabase LactMed (NCBI Bookshelf), 2026 · ncbi.nlm.nih.gov

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026summary, key facts, evidence, studied doses, who should avoid, research notes, safety, FAQ, questions, related	Added a 2023 trial in 90 heart attack patients (primary immune endpoint null, lower hsCRP, D). Added a 2026 lab study showing CYP3A4, CYP2C19 and CYP2E1 inhibition as a research note and a medicines caution (no human interaction data, so the interactions list stays empty). Cited LactMed's astragalus chapter in the pregnancy and breastfeeding note (no cycloastragenol entry). Replaced two FAQ items that repeated auto-generated questions with one on drug interactions; added page questions and the healthy-aging goal hub link. Fact-check: a 2025 TA-65 meta-analysis (PMID 41286474; '8 RCTs, 750 people') was not used: the references it lists as its included trials are mostly not TA-65 RCTs (an open-label program, a Mendelian randomization study, reviews, a trial protocol and the PRISMA statement), so its pooled results cannot be verified.	Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md
Oct 14, 2026all	Independent adversarial review: corrected the shared-author insight (five human studies are cited, not four) and added the TA-65 telomere trial's company ties from its disclosure statement.	Writer: Kymata Health EditorialTrigger: review
Oct 14, 2026all	Initial editorial evidence review (first draft). Every PMID checked against NCBI E-utilities esummary (titles and years taken from the record) and the abstract read for each cited row. Studied doses are reported as research doses, not dosing advice.	Writer: Kymata Health EditorialTrigger: new page

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