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.
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.
[2][6][7][8] Phytoestrogens mainly belong to a large group of substituted natural phenolic compounds: the coumestans, prenylflavonoids and isoflavones are three of the most active in estrogenic effects in this class.
[2] Mycoestrogens have similar structures and effects, but are not components of plants; these are mold metabolites of Fusarium, especially common on cereal grains,[9][10][11] but also occurring elsewhere, e.g. on various forages.
[14] The key structural elements that enable phytoestrogens to bind with high affinity to estrogen receptors and display estradiol-like effects are:[2] In addition to interaction with ERs, phytoestrogens may also modulate the concentration of endogenous estrogens by binding or inactivating some enzymes, and may affect the bioavailability of sex hormones by depressing or stimulating the synthesis of sex hormone-binding globulin (SHBG).
[citation needed] Phytoestrogens are ancient naturally occurring substances, and as dietary phytochemicals they are considered to have coevolved with mammals.
Studies have been conducted on screening methods for environmental estrogens present in manufactured supplementary food, with the purpose of aiding reproduction of endangered species.
[34] In humans, phytoestrogens are digested in the small intestine, poorly absorbed into the circulatory system, circulate in plasma, and are excreted in the urine.
[1][36][37] Additionally, other epidemiological studies found that consumption of soy estrogens is safe for patients with breast cancer, and that it may decrease mortality and recurrence rates.
[1][38][39] It remains unclear if phytoestrogens can minimize some of the deleterious effects of low estrogen levels (hypoestrogenism) resulting from oophorectomy, menopause, or other causes.
[36] A Cochrane review of the use of phytoestrogens to relieve the vasomotor symptoms of menopause (hot flashes) stated that there was no conclusive evidence to suggest any benefit to their use, although genistein effects should be further investigated.
[1] Some studies showed that isoflavone supplementation had a positive effect on sperm concentration, count, or motility, and increased ejaculate volume.
[54] Plants used that have been shown to contain phytoestrogens include Pueraria mirifica[55] and its close relative kudzu,[56] Angelica,[57] fennel,[28] and anise.
