phytoestrogens and Feminization

Concerns that the phytoestrogens (isoflavones) in soy may feminize men continue to be raised. Several studies and case-reports describing feminizing effects including lowering testosterone levels and raising estrogen levels in men have been published. For this reason, the clinical data were meta-analyzed to determine whether soy or isoflavone intake affects total testosterone (TT), free testosterone (FT), estradiol (E

Topics: Adolescent; Adult; Aged; Diet; Dietary Supplements; Estrogens; Feminization; Humans; Isoflavones; Male; Middle Aged; Phytoestrogens; Soybean Proteins; Testosterone; Young Adult

Phytoestrogens are present in certain edible plants being most abundant in soy; they are structurally and functionally analogous to the estrogens. Phytoestrogens have been applied for compensation of hormone deficiency in the menopause. At the same time, soy products are used in infant food and other foodstuffs. Furthermore, soy is applied as animal fodder, so that residual phytoestrogens and their active metabolites such as equol can remain in meat and influence the hormonal balance of the consumers. There have been only singular reports on modified gender-related behavior or feminization in humans in consequence of soy consumption. In animals, the intake of phytoestrogens was reported to impact fertility, sexual development and behavior. Feminizing effects in humans can be subtle and identifiable only statistically in large populations.. Phytoöstrogene sind in einigen essbaren Pflanzen enthalten, am reichlichsten in der Soja; sie sind strukturell und funktionell den natürlichen Östrogenen ähnlich. Die Phytoöstrogene werden für den Ausgleich des Hormondefizits in der Menopause verwendet. Gleichzeitig wird die Soja in der Säuglingsnahrung und anderen Lebensmitteln gebraucht. Außerdem wird die Soja als Viehfutter benutzt, sodass die Phytoöstrogene und deren aktive Metaboliten (Equol) im Fleisch verbleiben und die Homöostase der Geschlechtshormone bei den Verbrauchern beeinflussen können. Es gibt nur einzelne Mitteilungen über eine Änderung des geschlechtsassoziierten Verhaltens oder eine feminisierende Wirkung bei Menschen infolge des Sojakonsums. Eine Störung der geschlechtlichen Entwicklung, des Verhaltens und der Fertilität bei Tieren unter der Einwirkung der Phytoöstrogene ist bekannt. Die Feminisierung bei Menschen kann im Einzelfall geringfügig und nur statistisch in größeren Kontingenten nachweisbar sein.

Topics: Animal Feed; Animals; Female; Feminization; Fertility; Humans; Male; Phytoestrogens; Sexual Development; Soy Foods

Under aquaculture conditions, Japanese eels (

Topics: Anguilla; Animals; Female; Feminization; Genistein; Humans; Isoflavones; Male; Phytoestrogens

Evaluation of the potential benefits and risks offered by naturally occurring plant estrogens requires investigation of their potency and sites of action when consumed at natural dietary concentrations. Our investigations have examined the effects of a range of natural dietary concentrations of the most potent plant isoflavonoid, coumestrol, using a rat model and a variety of estrogen-dependent tissues and endpoints. Treatments of immature females demonstrated agonistic action in the reproductive tract, brain, and pituitary at natural dietary concentrations. Experiments designed to test for estrogen antagonism demonstrated that coumestrol did not conform to the picture of a classic antiestrogen. However, coumestrol did suppress estrous cycles in adult females. Developmental actions were examined by neonatal exposure of pups through milk of rat dams fed a coumestrol, control, or commercial soy-based diet during the critical period of the first 10 postnatal days or throughout the 21 days of lactation. The 10-day treatment did not significantly alter adult estrous cyclicity, but the 21-day treatment produced in a persistent estrus state in coumestrol-treated females by 132 days of age. In contrast, the 10-day coumestrol treatments produced significant deficits in the sexual behavior of male offspring. These findings illustrate the broad range of actions of these natural estrogens and the variability in potency across endpoints. This variability argues for the importance of fully characterizing each phytoestrogen in terms of its sites of action, balance of agonistic and antagonistic properties, natural potency, and short-term and long-term effects.

Topics: Animals; Coumestrol; Diet; Dose-Response Relationship, Drug; Estrogen Antagonists; Estrogens; Estrogens, Non-Steroidal; Estrus; Female; Feminization; Gonadotropins; Isoflavones; Luteinizing Hormone; Male; Phytoestrogens; Plant Preparations; Rats; Rats, Sprague-Dawley; Sexual Behavior, Animal; Time Factors