# 17α-Estradiol

17α-Estradiol is a mirror-image form of the main estrogen, 17β-estradiol. The technical word is a 'stereoisomer'. But it has far weaker feminizing effects. So it barely acts like estrogen in your body. In the NIA Interventions Testing Program, it reliably extended median lifespan in male mice. The likely routes are the brain and the metabolism. How it works is still not clear. And there is no human longevity data. It is not approved or proven as an anti-aging therapy for people.

## Sources

- Harrison DE, Strong R, Allison DB et al.. (2014). Acarbose, 17-α-estradiol, and nordihydroguaiaretic acid extend mouse lifespan preferentially in males. Aging Cell. https://doi.org/10.1111/acel.12170
- Harrison DE, Strong R, Reifsnyder P et al.. (2021). 17-α-estradiol late in life extends lifespan in aging UM-HET3 male mice; nicotinamide riboside and three other drugs do not affect lifespan in either sex. Aging Cell. https://doi.org/10.1111/acel.13328

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_Canonical: https://longevity-switzerland.com/en/glossary/17-alpha-estradiol · Part of Longevity Cities · Updated 2026-06-22_