Introduction Phytoestrogens and diet Effects and properties Dosage Mechanism of action Side effects
Mechanism of action
As anticipated, even though they do not have a steroid structure, phytoestrogens have numerous structural similarities with estrogens produced by the ovary and with anti-estrogenic drugs ( tamoxifen ). These particular characteristics allow it to interact with estrogen receptors.
Thanks to their structural ambivalence, phytoestrogens can exert both estrogenic and anti-estrogenic effects, in relation to the activated receptor, the tissue considered and the levels of circulating estrogens. More specifically, when the endogenous estrogens, therefore produced by the body, are high, the phytoestrogens exert antagonistic actions (they slow down their activity). On the contrary, when the level of endogenous estrogens is low, the phytoestrogens enhance its action, occupying and stimulating, even if weakly, their specific receptors.
The antiestrogenic action is favored not only by the receptor block, but also by the inhibition of the aromatase enzyme (lower conversion of androgens into estrogens) and by the increased hepatic synthesis of SHBG (with consequent reduction in the amount of free estradiol ).
The biological action of these “plant hormones” is very important, since the estrogens produced by the body are involved in the onset of various disorders and diseases. More in particular:
if present in excess, sex hormones and especially estrogen, can increase the incidence and promote the progress of some types of cancer, such as breast, prostate , uterus and ovarian cancers .
Hot flashes and other disorders associated with climacteric are a consequence of hormonal imbalances (decreased estrogen and alterations in the release of pituitary gonadotropins ).
Estrogen protects against cardiovascular disease and osteoporosis .
As for the antioxidant action , this is particularly high for the isoflavones genistein and dadzein (contained mainly in soy and derivatives). These substances are able to neutralize free radicals and prevent oxidative damage .
Fiotestrogens and Diet
Intake and absorption
The amount of phytoestrogens taken with the diet varies enormously from person to person, in relation to the consumption of certain foods . It is known, for example, that in Asian populations the consumption of phytoestrogens is particularly high, thanks to a diet traditionally rich in soy and derivatives. This particular eating habit has been linked to the lower incidence of breast cancer and menopausal symptoms recorded in Asian women.