Phytoestrogens in human diet –Risks and Benefits
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1
Aristotle University of Thessaloniki, Department of Pharmacology, Greece
Phytoestrogens are also called dietary estrogens and comprise a diverse group of naturally occurring non–steroidal plant compounds. Because of their structural similarity with 17β–estradiol, they have the ability to mimic estrogenic or/and anti–estrogenic effects on human physiology. Coumestans, prenylated flavonoids, stilbenes, isoflavones and the phytoalexin resveratrol are characterized as the most active compounds in this class. Isoflavones, which are commonly found in soy and red clover, seem to lead the research on the respective field. Lignans have also been identified as phytoestrogens, although they do not belong to flavonoids, while mycoestrogens, some mold metabolites of the fungus Fusarium that are found in pastures, alfalfa and clover, seem to be excluded by researchers, due to their rare presence in human diet. Coumestrol, the most biologically active coumestan, can be found in a variety of legumes, soybeans, brussel sprouts, spinach and clover. Its ability to modulate hormone production lies on the inhibition of aromatase and hydroxysteroid dehydrogenase. 8–Prenylnaringenin is the most abundant prenylated flavonoid, which is found in beer and hop and is known for its estrogenic and antioxidant properties. Isoflavones, being polyphenols, are antioxidants and are mainly found in soybeans as genistein and daidzein. Phytoestrogens exert their effects primarily through binding to estrogen receptors (ER–α and ER–β). The structural elements that enable phytoestrogens to bind with high affinity to ERs are their phenolic ring, their low molecular weight, their optimal hydroxylation pattern, the distance between two hydroxyl groups at the isoflavones nucleus and the ring of isoflavones mimicking a ring of estrogens at the receptors binding site. In the past, phytoestrogenic plants have been used in the treatment of menstrual and menopausal problems, as well as for fertility problems. Nowadays, Pueraria mirifica, kudzu, Angelica, fennel, anise and red cloves are used in this direction, but although they are safe, they do not seem to be effective enough in relieving menopausal symptoms. On the other hand, phytoestrogens seem to have more health beneficial properties, such as the prevention of breast and prostate cancers and osteoporosis, the improvement of cognitive function and the protection against cardiovascular disease, diabetes, inflammation and immunity problems. In the future, metabolic engineering of plants could generate novel and exquisitely controlled dietary sources, while current studies on nutrigenomics by means of microarrays reveal more potential health benefits and risks of the respective substances.
Keywords:
Phytoestrogen,
isoflavone,
soy,
Health,
Diet
Conference:
8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010, Thessaloniki, Greece, 1 Oct - 5 Oct, 2010.
Presentation Type:
Invited speaker
Topic:
Xenobiotics and reproduction
Citation:
Kyriakidis
I
(2010). Phytoestrogens in human diet –Risks and Benefits.
Front. Pharmacol.
Conference Abstract:
8th Southeast European Congress on Xenobiotic Metabolism and Toxicity - XEMET 2010.
doi: 10.3389/conf.fphar.2010.60.00153
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Received:
05 Mar 2011;
Published Online:
04 Nov 2010.
*
Correspondence:
Dr. Ioannis Kyriakidis, Aristotle University of Thessaloniki, Department of Pharmacology, Thessaloniki, Greece, kyriakidis@med.uoc.gr