History
In 1923 Edgar Allen and Edward Doisy at Washington University injected fluid from pig ovarian follicles into rats and triggered estrous cycles, the first proof of an ovarian hormone. In 1929 Doisy and Germany's Adolf Butenandt independently isolated crystalline estrone from pregnant women's urine, and in the 1930s estradiol, the most potent form, was identified. Premarin, derived from pregnant mares' urine, was approved for menopause in 1942, popularizing hormone therapy, and the first contraceptive pill, approved in 1960, combined estrogen with a progestin.
What it does
Estrogen drives breast development and the menstrual cycle at puberty and thickens the uterine lining before ovulation. It helps bone-building cells maintain density, keeps blood vessels supple, lowering cardiovascular risk before menopause, and affects skin collagen, vaginal tissue and memory and mood. In men, some testosterone is converted to estradiol by the aromatase enzyme and used for bone and sperm production. When estrogen plunges at menopause, hot flashes, poor sleep and vaginal dryness appear as part of menopause, and osteoporosis risk rises, while estrogen-fed endometriosis usually eases.
The hormone therapy debate
In 2002 the US Women's Health Initiative reported that estrogen plus progestin raised the risk of breast cancer, heart attack, stroke and blood clots, and hormone-therapy prescriptions worldwide fell by nearly half. Later analyses noted the participants' average age was 63, and a "timing hypothesis" gained ground: started before 60 or within ten years of menopause, benefits often outweigh risks. Bodies such as the North American Menopause Society now advise the lowest effective dose for people with troublesome symptoms after weighing individual risk. Plant phytoestrogens like soy isoflavones are weak and variable and can't replace treatment.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- What are the symptoms of low estrogen?
- Hot flashes, night sweats, insomnia, vaginal dryness, irregular periods and mood changes are typical, with bone loss over the long term. If your periods stop at a young age, see a doctor.
- Does eating soy or pomegranate raise estrogen?
- Soy isoflavones act like a weak estrogen but don't raise your own levels; evidence for pomegranate is even thinner.
Sources reviewed: 2026-10-26
References
- Allen, E., & Doisy, E. A. (1923). An ovarian hormone: preliminary report on its localization, extraction and partial purification, and action in test animals. JAMA, 81(10), 819–821.
- Writing Group for the Women's Health Initiative Investigators (2002). Risks and benefits of estrogen plus progestin in healthy postmenopausal women. JAMA, 288(3), 321–333.
- The 2022 hormone therapy position statement of The North American Menopause Society. Menopause, 29(7), 767–794.