Genistein - an agent of endocrine disruptive effects and relief of menopausal disorders
Phytoestrogens can have both positive and negative effects.
Depending on your age, sex and occupation, you may have different associations with the term 'phytoestrogen'. For the young environmental or health scientist, it may be associated with endocrine disruptive effects; while for the middle-aged female, it may signify relief from menopausal disorders.
Phytoestrogens are non-steroidal compounds naturally produced by plants that have the ability to elicit weak estrogenic or anti-estrogenic effects by interacting with endocrine receptors due to the similarity of the compounds to 17β-estradiol. There are four main compound categories causing phytoestrogenic effects: flavonoids, lignans, coumestans and stilbenes. The flavonoids is one of the largest and most studied groups with more than 10,000 compounds, and can be further divided into six subclasses: flavonols, flavones, flavanones, flavanols, anthrocyanins and isoflavones. The function of the flavonoids in the plants is thought to be protection against ultraviolet irradiation and defense against pathogens and insect pests. Phytoestrogens are found in many different plants, mainly legumes.
Genistein is one of the most well-known phytoestrogens. It is especially characteristic of soy beans, but can also be found in smaller amounts in e.g. red clover. It has further been detected in the aqueous environment in relation to agricultural activity and waste water. In soy, it is predominantly found as the inactive glycoside genistin, which can be hydrolyzed by acid and β-glycosidase in the human gut or environment to yield genistein. It belongs to the compound class isoflavones due to the 3-phenyl-1-benzopyran-4-one backbone; the specific location of the phenyl group distinguishes the isoflavones from the flavones.
Besides its role in hormonal regulation, genistein has been shown to have positive effects in relation to osteoporosis, cardiovascular diseases and as an antioxidant, while its role in breast cancer prevention is debatable. The potential endocrine disruptive effects include malformations in the ovary, uterus and prostate, early puberty, reduced fertility and reproductive tract cancers. Especially infants appear at risk when fed soy formula as a replacement for breastfeeding.
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Photo credit, from left to right:
- Edamame beans: By Tammy Green (aka Zesmerelda) from Chicago Upscale Dining + Lounge Republic Pan-Asian Restaurant [http://www.republicrestaurant.us/ in Ontario & Rush Street, Chicago, Illinois 60611] (Flickr) [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
- Soy nut: By Midori (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
- Mature soybean on plant: By Vijayanrajapuram (Own work) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
ESR4 Bettina Gro Sørensen