Soy Protein Isolates of Varying Isoflavone Content Exert Minor Effects on Serum Reproductive Hormones in Healthy Young Men,

Dillingham, Barbara L.; McVeigh, Brianne L.; Lampe, Johanna W.; Duncan, Alison

doi:10.1093/jn/135.3.584

Cited by 47 publications

(32 citation statements)

References 55 publications

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“…The overall increase in PSA over time was most likely to aging of the participants. Unlike previous studies (Gardner-Thorpe et al, 2003;Dillingham et al, 2005), the present study observed no effect on serum testosterone levels. The short duration and limited sample size may have prevented a substantial effect due to soy foods.…”

Section: Discussioncontrasting

confidence: 99%

“…In animal studies, evidence has emerged that prepubertal soy exposure may be more protective than adult intake (Lamartiniere et al, 2002). Some studies have suggested that soy may also affect other sex hormones, such as DHT, estrone and estradiol (Habito et al, 2000;Nagata et al, 2000;Dillingham et al, 2005). Moreover, isoflavones may protect against prostate cancer through non-hormonal mechanisms (Wang et al, 2003;Hedlund et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…A randomized double-blind intervention study of a dietary supplement containing soy isoflavones, phytosterols, and other nutrients noted a significant reduction in circulating testosterone, dihydrotestosterone (DHT), and free prostate-specific antigen (PSA) levels among prostate cancer patients (Kranse et al, 2005). An intervention with soy protein isolate showed significantly lower serum DHT levels and a decreased DHT/testosterone ratio at the end after a low soy and a high soy diet as compared to the control diet (Dillingham et al, 2005). Few nutritional interventions have investigated the influence of soy foods rather than supplements on sex hormones in men although whole foods are more likely to avoid toxicities connected with extremely high isoflavone doses (Ryokkynen et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men

et al. 2006

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Background: Low prostate cancer incidence and high soy intake in Asian countries suggest a possible protective effect of soy foods against prostate cancer. The goal of this pilot study was to evaluate the feasibility of a randomized, crossover soy trial among men and to investigate the effects of daily soy intake on serum prostate-specific antigen (PSA) and testosterone levels. Methods: We randomized 24 men to a high or a low soy diet for 3 months. After a 1-month washout period, the men crossed over to the other treatment. During the high soy diet, the men consumed two daily soy servings; during the low soy diet, they maintained their usual diet. During the entire study each man donated four blood samples and five overnight urine samples. Dietary compliance was assessed by soy calendars, 24-h dietary recalls, and urinary isoflavone excretion measured by highpressure liquid chromatography with photodiode array detection. Blood samples were analyzed for serum testosterone and PSA by radioimmunoassay. When necessary, variables were log transformed. Two sample t-tests compared the two groups before each study period. Mixed models incorporating the repeated measurements were used to evaluate the effect of the soy diet on urinary isoflavone excretion and serum analytes. Results: Twenty-three men aged 58.777.2 years completed the study. The compliance with the study regimen was high according to self-reported soy food intake and urinary isoflavone excretion. No significant between-group and within-group differences were detected. During the high soy diet, dietary isoflavone intake and urinary isoflavone excretion increased significantly as compared to the low soy diet. A 14% decline in serum PSA levels (P ¼ 0.10), but no change in testosterone (P ¼ 0.70), was observed during the high soy diet in contrast to the low soy diet. Conclusion: The high adherence as shown by three measures of compliance in this pilot trial demonstrated the feasibility of an intervention based on soy foods among free-living men.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men

et al. 2006

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“…Both these studies conveyed the lack of a protective role of isoflavone on prostate cancer risk in healthy men. Dillingham et al [58] studied the effect of soy protein isolates on reproductive hormones in young men 20 to 40 years of age. They randomized 35 healthy men to receive either milk protein isolate or low-isoflavone soy protein isolate (1.64 ± 0.19 mg isoflavones/day) or high-isoflavone soy proteins isolate (61.7 ± 7.35 mg isoflavones/day) for 57 days in a randomized crossover design.…”

Section: Human Trials Of Phytoestrogens and Prostate Health And Diseasementioning

confidence: 99%

Phytoestrogens and their Potential Role in Prostate Cancer Prevention and Treatment

Kolukula¹

2011

J Cancer Sci Ther

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Phytoestrogens are hormonally active compounds present in plant foods that are being studied extensively for their potential roles in hormonally-sensitive neoplasms such as prostate cancer. We postulate that the evidence for a protective role of phytoestrogens is not conclusive enough for a general recommendation for their use as dietary supplements, but phytoestrogens can be considered for therapeutic use in prostate cancer patients under certain circumstances. A literature review was performed to study the evidence regarding the chemopreventive role of phytoestrogens in healthy men, the protective role in early prostate cancer, and a possible therapeutic role in advanced prostate cancer patients. Dietary supplementation with phytoestrogens for chemoprevention of prostate cancer is still a debatable subject. Numerous pre-clinical in vitro studies have been promising, and novel molecular mechanisms of action for phytoestrogens continue to be identified. However, human clinical trials including studies done on prostate biomarkers and on the effects of phytoestrogens on steroid hormones are complicated by the possibility of local paracrine effects in prostatic tissue by phytoestrogens that are steroid-like in structure. Their interaction with multiple enzymes represents a paradigm for the complexity of phytoestrogen effects and a window into a potential reason that study results are inconsistent or difficult to explain. A final outcome of the phytoestrogen effect in the intact human may be difficult to discern because these agents can inhibit or induce enzymes, destroy cancer cells, yet will have intrinsic estrogenic effects themselves. Larger multi-center, multi-national, randomized controlled trials are needed before definitive recommendations can be made on the usefulness of phytoestrogens for chemoprevention and therapy for prostate cancer. However, combinations of phytoestrogens with radiation therapy and other antioxidants in advanced or metastatic prostate cancer can be considered because there are limited effective therapy options for this group of patients.

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“…We did not evaluate isoflavone content, as a correlation between the content and effects on testosterone has not been consistent (2)(3)(4)(5). Instead, we assessed the effect of this product on estrogen receptor-a and estrogen receptor-h in an in vitro assay.…”

Section: Effect Of Soy Protein On Testosterone Levelsmentioning

confidence: 99%

Effect of Soy Protein on Testosterone Levels

Goodin¹,

Shih²,

Gallo³

et al. 2007

Cancer Epidemiology, Biomarkers &Amp; Prevention

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Soy Protein Isolates of Varying Isoflavone Content Exert Minor Effects on Serum Reproductive Hormones in Healthy Young Men,

Cited by 47 publications

References 55 publications

Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men

Serum prostate-specific antigen but not testosterone levels decrease in a randomized soy intervention among men

Phytoestrogens and their Potential Role in Prostate Cancer Prevention and Treatment

Effect of Soy Protein on Testosterone Levels

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