Men.   To date, there have been very few reported studies examining the effects of phytoestrogens specifically in men. There appear to be no clear gender differences in the bioavailability or metabolism of isoflavones or lignans, and therefore many of the potential benefits attributed to dietary phytoestrogens are probably applicable to men. The hypocholesterolemic effects of soy protein have been demonstrated in many studies of hypercholesterolemic adult men (see, for example, Potter et al. 1993[] ), and these have been discussed above. Two dietary intervention studies searched for evidence of hormonal effects in men, and the results suggested only minimal effects. A study of middle-aged men fed 60 g/d of TVP found no significant hormonal modifications (Cassidy et al. 1998[] ), whereas 60 g/d of a soy isolate beverage had no significant effects on serum cholesterol levels or platelet aggregation (Gooderham et al. 1996[] ). These findings contrast with the significant hormonal effects observed in women from similar intakes of soy foods; the reasons for this gender difference in responsiveness are unclear. Prostatic cancer is responsive to estrogen therapy, and it is known that phytoestrogen intake is higher in countries in which the incidence rates of prostatic cancer and other conditions linked to estrogen exposure (hypospadia, testicular cancers) are low. Analysis of the plasma and prostatic fluid from Asian men (Morton et al. 1997[] ), who have a low risk for prostate cancer relative to European men, found high concentrations of the isoflavones, equol and daidzein; genistein was not measured. This type of data has consequently led to speculation that dietary phytoestrogens may play a role in the reduced risk for prostatic cancer that is evident from some epidemiologic studies. In the absence of solid data from clinical studies, circumstantial evidence in support of this contention comes only from invitro and animal studies. In vitro, the isoflavone, genistein inhibits steroid 5[]-reductase and 17ß-hydroxysteroid dehydrogenase in genital skin fibroblasts (Evans et al. 1995[] , Makela et al. 1995a[] ); these two enzymes are involved in the synthesis of androgens and estrogens. Genistein and biochanin A have both been shown to inhibit the growth of prostatic cancer cells in vitro, irrespective of whether these were androgen-dependent or -independent cell lines (Peterson and Barnes 1991 and 1993[] [] ). The severity and incidence of prostatitis in the lateral lobe of the prostate in a rat model of prostatitis were reduced when the animals were fed a soy-rich diet (Sharma et al. 1992[] ). Inflammation may play a key role in tumor formation by mechanisms involving cytokine release, free radical formation and subsequent DNA damage, and a reduction in the extent of inflammation may in general be considered to be beneficial in reducing cancer risk. In subsequent studies, Pollard and Luckert (1997)[] showed in a rat model that an isoflavone-rich diet reduced the incidence of prostate cancer and prolonged the disease-free period by 27%. However, these effects were observed only if the soy was fed before the induction of cancer. Mice treated neonatally with diethylstilbestrol showed hyperplastic and dysplastic changes in the prostate, which were partially prevented by the addition of soy isoflavones (Makela et al. 1995b[] ). However in adult male animals, no estrogenic or antiestrogenic effects of soy were apparent (Makela et al. 1995c[] ). Studies are necessary and will undoubtedly be carried out to establish whether phytoestrogens exert consistent biological effects in men. This will be particularly important given the current concerns, controversial as they are, concerning the relationship between the declining sperm count and environmental estrogen exposure (Sharpe and Skakkebaek 1993[] ).   Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.