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17α-Estradiol (non-feminizing estrogen)
A 'non-feminizing' stereoisomer of estradiol that extended lifespan in male mice in the NIA aging program — with little estrogenic (feminizing) activity. Honest appraisal: the evidence is entirely animal, the benefit is male-specific (it can harm female reproductive aging), and there are no human data. A research compound, not an approved drug or supplement.
Research compound — not a dietary supplement
17-Alpha-Estradiol is a research compound, not a regulated dietary supplement. It is sold for research or off-label use. The evidence below is largely preclinical (animal and in-vitro) or early-stage, so no evidence score is assigned. This page is provided for transparency and education — it is not a recommendation to use. Consult a qualified healthcare provider, and be aware that purity, dosing, and legal status vary by jurisdiction.
What the evidence says
Most 17-Alpha-Estradiol studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality randomised trials published 1980–2024.
Based on 6 studies · 1 RCT
Confidence
Low confidenceBy outcome
17α-Estradiol reproducibly extended lifespan in male mice with minimal feminizing activity, but the evidence is entirely animal, the benefit is male-specific (and can harm female reproductive aging), and there are no human data — so it is a preclinical-only research compound.
No trials currently enrolling · 2 completed on ClinicalTrials.gov
1 of the completed trials have posted results
Registered trials show research momentum for 17-Alpha-Estradiol, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Aug 2026
17α-Estradiol is the alpha stereoisomer of the main human estrogen 17β-estradiol.
Its interest in geroscience comes from a striking property: in the NIA Interventions Testing Program it extended lifespan in male mice while having minimal classical estrogenic (feminizing) activity — hence 'non-feminizing estrogen.' Mechanistic work suggests it improves metabolic and inflammatory markers of aging in males, reduces adipose-tissue inflammation, and acts partly through estrogen-receptor-beta and brain/hypothalamic signaling, in a way that depends on intact gonads (it largely fails to extend lifespan in castrated males).
The honest evidence picture is narrow: all efficacy data are in mice, the benefit is male-specific (and at least one study found it promotes ovarian aging in females), and there are no human pharmacokinetic, efficacy, or safety studies for longevity.
It is not an approved human drug in most markets (a related compound, alfatradiol, is used topically for hair loss), so grey-market '17α-estradiol' sold for longevity is an unregulated research chemical of uncertain purity, with unknown human dosing and long-term hormonal effects.
The score reflects an interesting, reproducible male-mouse lifespan result with zero human data and real sex-specific caveats.
The alpha stereoisomer has low affinity for classical estrogen receptors, giving metabolic/longevity effects in males with minimal feminization.
Reduces adipose-tissue inflammation and improves insulin sensitivity and metabolic markers in aged male mice.
Effects appear to act partly via estrogen-receptor-beta and brain signaling, and require intact gonads (sex-specific).
How 17-Alpha-Estradiol works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Avoid — benefit is male-specific and it can promote ovarian aging in models.
Avoid — it is still an estrogen stereoisomer with uncharacterized human activity.
Research-use-only; no human validation.
Tip: No human safety data; long-term endocrine effects unquantified.
The current evidence for 17-Alpha-Estradiol is insufficient to assign an evidence score, based on 6 indexed studies. A 'non-feminizing' stereoisomer of estradiol that extended lifespan in male mice in the NIA aging program — with little estrogenic (feminizing) activity. Honest appraisal: the evidence is entirely animal, the benefit is male-specific (it can harm female reproductive aging), and there are no human data. A research compound, not an approved drug or supplement. Representative study: PMID 27312235.
The commonly studied dose of 17-Alpha-Estradiol is No validated human dose. The mouse studies delivered it in food at defined ppm; grey-market oral dosing for longevity is anecdotal and unsupported by any human data.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for 17-Alpha-Estradiol — consistent daily use matters more than the time of day. No validated human dosing or schedule; research-use-only compound.
17-Alpha-Estradiol should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are unknown human hormonal effects. Use caution if any of these apply to you: Pregnancy / breastfeeding; Women (sex-specific harms; promotes ovarian aging in models); Hormone-sensitive conditions.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 6 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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