Gli isoflavoni (fitoestrogeni vegetali contenuti nella ad es. nella soia) ad esempio regolano naturalmente la produzione ormonale corporea.
Gli isoflavoni sono simili nella loro struttura agli estrogeni nel corpo umano e quindi aggiungere la soia alla nostra dieta può essere un modo di aumentare i livelli di estrogeni.
Hanno un vantaggio decisivo rispetto agli ormoni chimici : manifestano il loro effetto solo in caso di carenza di estrogeni.
Questo effetto equilibratore è particolarmente utile per le donne che desiderano sia assicurarsi un corretto e regolare equilibrio ormonale.
Gli isoflavoni della soia bloccano anche la ricezione di estrogeni pericolosi e cancerogeni di origine chimica, aiutando così a proteggere il seno (e il corpo in generale) dai rischi di tumori. Ci sono numerosi studi clinici sugli effetti di prevenzione del cancro degli isoflavoni della soia.
Uno studio clinico controllato ha valutato l'effetto degli isoflavoni sul metabolismo osseo, per verificare il loro effetto protettivo contro la perdita di massa ossea tipica delle donne in menopausa. La ricerca si è svolta su 40 giapponesi apparentemente sane ed in menopausa, divise in due gruppi. Per 10 settimane, il primo gruppo ha assunto 37,3 mg al giorno di isoflavoni, il secondo un placebo. All'inizio e al termine dello studio, è stata fatta la valutazione dell'eliminazione con l'urina degli isoflavoni e del calcio. Si è visto che i soggetti del gruppo isoflavoni avevano un'eliminazione di calcio nettamente inferiore a quella delle donne del gruppo placebo. L'eliminazione degli isoflavoni con le urine era invece superiore nelle donne che li prendevano, e questo indica che erano stati correttamente assorbiti. Non sono stati notati effetti collaterali degni di nota. Lo studio conferma che l'ingestione continuata degli isoflavoni, anche a dosi basse come quelle utilizzate in questa ricerca, è capace di ostacolare la perdita della massa ossea nella donna in menopausa. Dosi più elevate dovrebbero consentire di ottenere risultati ancora migliori, specialmente combinando gli isoflavoni con l'inulina, che ne favorisce l'assorbimento intestinale.
Nelle donne asiatiche ad esempio vi è una incidenza bassissima di alopecia androgenetica post-menopausale, a causa di una alimentazione ricca di soia.
I fitoestrogeni (ad esempio quelli contenuti nella soia) possono proteggere efficacemente gli uomini dal carcinoma della prostata e le donne dalle malattie legate alla produzione di estrogeni quali il carcinoma della mammella, l'endometriosi, la mastopatia fibrocistica (cioè la malattia fibrocistica del seno), i fibromi dell'utero ed i disturbi della menopausa. La bassa percentuale di queste patologie tra le donne giapponesi potrebbe essere dovuta al loro forte consumo di cibi a base di soia, specialmente di tofu. In effetti, le donne asiatiche non hanno neppure un termine nelle loro lingue per le "vampate di calore" - non sanno proprio cosa siano!
Gli isoflavoni hano dimostrato di inibire la crescita di cellule umane di cancro al seno e al polmone. In aggiunta, un uso regolare delle proteine della soia (fagioli di soia, tofu, bevande di soia, ecc.) può abbassare il colesterolo nel sangue e i livelli di trigliceridi dal 10 al 15 per cento., soprattutto in persone con livelli elevati di lipidi.
I fitoestrogeni (genistein e daidzein) dalla soia come alternative potenziali alla tradizionale terapia ormonale sostitutiva particolarmente perché possono essere protettivi contro il cancro al seno e sono antiestrogeni per l'endometrio ovviando così al bisogno della progestina.
Per proteggere le ossa della donna in menopausa oltre all'uso di fitoestrogeni (con debole azione estrogenica) a volte si abbinano calcio, vitamina D3, inulina (prebiotico derivato dalla cicoria che facilita l'azione degli isoflavoni).
Gli isoflavoni possono essere somministrati per lunghi periodi, anche nel periodo post-menopausa, per renderli ancora più efficaci è bene aiutare l'organismo a trasformare i glicosidi (la forma in cui gli isoflavoni sono presenti nelle piante) in veri e propri fitoestrogeni. Questa trasformazione avviene ad opera dei batteri intestinali e l'inulina, una fibra vegetale che ha un positivo effetto regolatore sulla flora intestinale.
Ci sarebbe il bisogno di ulteriori studi clinici ampi e controllati per incentivarne l'utilizzo.
Prodotti che contengono i fitoestrogeni sono : borragine, finocchio, soia, promensil, triko ok donna, wonderup (il miglior mix di fitoestrogeni).
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