Phytoestrogen

A phytoestrogen is a plant-derived xenoestrogen (a type of estrogen produced by organisms other than humans) not generated within the endocrine system, but consumed by eating plants or manufactured foods.[1] Also called a "dietary estrogen", it is a diverse group of naturally occurring nonsteroidal plant compounds that, because of its structural similarity to estradiol (17-β-estradiol), have the ability to cause estrogenic or antiestrogenic effects.[2] Phytoestrogens are not essential nutrients because their absence from the diet does not cause a disease, nor are they known to participate in any normal biological function.[2] Common foods containing phytoestrogens are soy protein, beans, oats, barley, rice, coffee, apples, carrots (see Food Sources section below for bigger list).

Its name comes from the Greek phyto ("plant") and estrogen, the hormone which gives fertility to female mammals. The word "estrus" (Greek οίστρος) means "sexual desire", and "gene" (Greek γόνο) is "to generate". It has been hypothesized that plants use a phytoestrogen as part of their natural defense against the overpopulation of herbivore animals by controlling female fertility.[3][4]

The similarities, at molecular level, of an estrogen and a phytoestrogen allow them to mildly mimic and sometimes act as an antagonist of estrogen.[2] Phytoestrogens were first observed in 1926,[2][5] but it was unknown if they could have any effect in human or animal metabolism. In the 1940s and early 1950s, it was noticed that some pastures of subterranean clover and red clover (phytoestrogen-rich plants) had adverse effects on the fecundity of grazing sheep.[2][6][7][8]

Chemical structures of the most common phytoestrogens found in plants (top and middle) compared with estrogen (bottom) found in animals
  1. ^ "Isoflavones". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis. October 2016. Retrieved 6 August 2022.
  2. ^ a b c d e Yildiz F (2005). Phytoestrogens in Functional Foods. Taylor & Francis Ltd. pp. 3–5, 210–211. ISBN 978-1-57444-508-4.
  3. ^ Hughes CL (Jun 1988). "Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens". Environmental Health Perspectives. 78: 171–4. doi:10.1289/ehp.8878171. PMC 1474615. PMID 3203635.
  4. ^ Bentley GR, Mascie-Taylor CG (2000). Infertility in the modern world: present and future prospects. Cambridge, UK: Cambridge University Press. pp. 99–100. ISBN 978-0-521-64387-0.
  5. ^ Varner JE, Bonner J (1966). Plant Biochemistry. Academic Press. ISBN 978-0-12-114856-0.
  6. ^ Bennetts HW, Underwood EJ, Shier FL (1946). "A specific breeding problem of sheep on subterranean clover pastures in Western Australia". Australian Veterinary Journal. 22 (1): 2–12. doi:10.1111/j.1751-0813.1946.tb15473.x. PMID 21028682.
  7. ^ Cunningham IJ, Hogan KG (1954). "Oestrogens in New Zealand pasture plants". N. Z. Vet. J. 2 (4): 128–134. doi:10.1080/00480169.1954.33166.
  8. ^ Johnston I (2003). Phytochem Functional Foods. CRC Press Inc. pp. 66–68. ISBN 978-0-8493-1754-5.