Définition
Estrogen is the primary female sex hormone produced mainly by the ovaries. It regulates the menstrual cycle, maintains bone density, supports cardiovascular health, protects cognitive function, and has broad anti-inflammatory effects. Its decline at perimenopause is one of the most impactful biological transitions in women's lives.
Estrogen is not a single hormone but a family of compounds: estradiol (E2) is the most potent form during reproductive years; estriol (E3) predominates during pregnancy; estrone (E1) is the main form after menopause, synthesized in adipose tissue. Estradiol is produced primarily by the ovarian follicles and regulated by the hypothalamic-pituitary-ovarian (HPO) axis.
Estrogen acts on virtually every tissue in the body. In the cardiovascular system: it maintains endothelial function, supports nitric oxide production, and keeps ApoB lower while maintaining HDL — the primary explanation for women's lower cardiovascular disease risk compared to age-matched men during reproductive years, a protection that diminishes rapidly after menopause. In bone: estrogen suppresses osteoclast activity, preserving bone matrix. Bone density can decline 1–3% per year in the early post-menopausal years without estrogen support.
In the brain: estrogen supports neuronal glucose uptake, synaptic plasticity, and serotonin-dopamine balance. Brain fog, mood changes, and memory lapses during perimenopause are direct neurological consequences of declining estradiol. In the gut: estrogen influences microbiome composition through the estrobolome — the subset of gut bacteria that metabolize estrogens. Dysbiosis can impair estrogen recycling and worsen hormonal imbalance.
Estrogen also directly suppresses NF-κB — the master inflammatory transcription factor — explaining its broad anti-inflammatory role. Loss of estrogen protection is a key driver of the inflammaging acceleration seen at menopause.
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