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1. Decreases androgen receptor expression.
J Nutr. 2007 Jul;137(7):1769-1775. Links
Isoflavone-Rich Soy Protein Isolate Suppresses Androgen Receptor Expression without Altering Estrogen Receptor-{beta} Expression or Serum Hormonal Profiles in Men at High Risk of Prostate Cancer.Hamilton-Reeves JM, Rebello SA, Thomas W, Slaton JW, Kurzer MS.
Department of Food Science and Nutrition; 5Division of Biostatistics in the School of Public Health 6Department of Urologic Surgery, University of Minnesota, Minneapolis, MN 55455 and 7Department of Urology, Veterans Administration Medical Center, Minneapolis, MN 55417.
The purpose of this study was to determine the effects of soy protein isolate consumption on circulating hormone profiles and hormone receptor expression patterns in men at high risk for developing advanced prostate cancer. Fifty-eight men were randomly assigned to consume 1 of 3 protein isolates containing 40 g/d protein: 1) soy protein isolate (SPI+) (107 mg/d isoflavones); 2) alcohol-washed soy protein isolate (SPI-) (<6 mg/d isoflavones); or 3) milk protein isolate (0 mg/d isoflavones). For 6 mo, the men consumed the protein isolates in divided doses twice daily as a partial meal replacement. Serum samples collected at 0, 3, and 6 mo were analyzed for circulating estradiol, estrone, sex hormone-binding globulin, androstenedione, androstanediol glucuronide, dehydroepiandrosterone sulfate, dihydrotestosterone, testosterone, and free testosterone concentrations by RIA. Prostate biopsy samples obtained pre- and postintervention were analyzed for androgen receptor (AR) and estrogen receptor-beta expression by immunohistochemistry. At 6 mo, consumption of SPI+ significantly suppressed AR expression but did not alter estrogen receptor-beta expression or circulating hormones. Consumption of SPI- significantly increased estradiol and androstenedione concentrations, and tended to suppress AR expression (P = 0.09). Although the effects of SPI- consumption on estradiol and androstenedione are difficult to interpret and the clinical relevance is uncertain, these data show that AR expression in the prostate is suppressed by soy protein isolate consumption, which may be beneficial in preventing prostate cancer.
2. Soy protein is beneficial for cardiovascular health and raising SHBG
The purpose of this study was to determine the effects of soy protein isolate consumption on circulating hormone profiles and hormone receptor expression patterns in men at high risk for developing advanced prostate cancer. Fifty-eight men were randomly assigned to consume 1 of 3 protein isolates containing 40 g/d protein: 1) soy protein isolate (SPI+) (107 mg/d isoflavones); 2) alcohol-washed soy protein isolate (SPI-) (<6> 5.5 mmol/l were given ISP+ for 12 weeks. In this male study there was a significant increase in HDL cholesterol (HDL-C) and SHBG. Soy protein has a cholesterol lowering effect in both women and men. These studies suggest that this effect is independent of isoflavones. Soy protein also reduces SHBG levels in both sexes.
3.Soy lowers DHT and decreases the DHT/Testosterone ratio.
J Nutr. 2005 Mar;135(3):584-91. Links
Soy protein isolates of varying isoflavone content exert minor effects on serum reproductive hormones in healthy young men.Dillingham BL, McVeigh BL, Lampe JW, Duncan AM.
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Inverse associations between soy and prostate cancer and the contribution of hormones to prostate cancer prompted the current study to determine whether soy protein could alter serum hormones in men. Thirty-five men consumed milk protein isolate (MPI), low-isoflavone soy protein isolate (SPI) (low-iso SPI; 1.64 +/- 0.19 mg isoflavones/d), and high-iso SPI (61.7 +/- 7.35 mg isoflavones/d) for 57 d each in a randomized crossover design. Twenty-four-hour urine samples indicated that urinary isoflavones were significantly increased by the high-iso SPI relative to the low-iso SPI and MPI. Serum collected on d 1, 29, and 57 of each treatment revealed that dihydrotestosterone (DHT) and DHT/testosterone were significantly decreased by the low-iso SPI [9.4% (P = 0.036) and 9.0% (P = 0.004), respectively] and the high-iso SPI [15% (P = 0.047) and 14% (P = 0.013), respectively], compared with the MPI at d 57. Other significant effects included a decrease in testosterone by the low-iso SPI relative to the MPI (P = 0.023) and high-iso SPI (P = 0.020) at d 29; an increase in dehydroepiandrosterone sulfate by the low-iso SPI relative to the MPI at d 29 (P = 0.001) and relative to the MPI (P = 0.0003) and high-iso SPI (P = 0.005) at d 57; and increases in estradiol and estrone by the low-iso SPI relative to the MPI at d 57 (P = 0.010 and P = 0.005, respectively). In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone with minor effects on other hormones, providing evidence for some effects of soy protein on hormones. The relevance of the magnitude of these effects to future prostate cancer risk requires further investigation.
So, soy protein isolate consumption (with varying levels of isoflavones, I believe) decreases androgen receptor expression, mildly reduce DHT and the DHT to testosterone ratio, and assists with raising SHBG levels while having positive effects on lipoprotein and cholesterol levels.
The additional benefit to prostate health is quite convincing, as well. I really think that soy products (not necessarily what you'll find at your convenience store) should be a part of the diet of every sufferer of male pattern baldness.
Any additional input would be appreciated. I do know that fermented soy is safer, but I really don't know what affect the fermenation process has on isoflavone levels or if it degrades the soy protein in any way.
J Nutr. 2007 Jul;137(7):1769-1775. Links
Isoflavone-Rich Soy Protein Isolate Suppresses Androgen Receptor Expression without Altering Estrogen Receptor-{beta} Expression or Serum Hormonal Profiles in Men at High Risk of Prostate Cancer.Hamilton-Reeves JM, Rebello SA, Thomas W, Slaton JW, Kurzer MS.
Department of Food Science and Nutrition; 5Division of Biostatistics in the School of Public Health 6Department of Urologic Surgery, University of Minnesota, Minneapolis, MN 55455 and 7Department of Urology, Veterans Administration Medical Center, Minneapolis, MN 55417.
The purpose of this study was to determine the effects of soy protein isolate consumption on circulating hormone profiles and hormone receptor expression patterns in men at high risk for developing advanced prostate cancer. Fifty-eight men were randomly assigned to consume 1 of 3 protein isolates containing 40 g/d protein: 1) soy protein isolate (SPI+) (107 mg/d isoflavones); 2) alcohol-washed soy protein isolate (SPI-) (<6 mg/d isoflavones); or 3) milk protein isolate (0 mg/d isoflavones). For 6 mo, the men consumed the protein isolates in divided doses twice daily as a partial meal replacement. Serum samples collected at 0, 3, and 6 mo were analyzed for circulating estradiol, estrone, sex hormone-binding globulin, androstenedione, androstanediol glucuronide, dehydroepiandrosterone sulfate, dihydrotestosterone, testosterone, and free testosterone concentrations by RIA. Prostate biopsy samples obtained pre- and postintervention were analyzed for androgen receptor (AR) and estrogen receptor-beta expression by immunohistochemistry. At 6 mo, consumption of SPI+ significantly suppressed AR expression but did not alter estrogen receptor-beta expression or circulating hormones. Consumption of SPI- significantly increased estradiol and androstenedione concentrations, and tended to suppress AR expression (P = 0.09). Although the effects of SPI- consumption on estradiol and androstenedione are difficult to interpret and the clinical relevance is uncertain, these data show that AR expression in the prostate is suppressed by soy protein isolate consumption, which may be beneficial in preventing prostate cancer.
2. Soy protein is beneficial for cardiovascular health and raising SHBG
The purpose of this study was to determine the effects of soy protein isolate consumption on circulating hormone profiles and hormone receptor expression patterns in men at high risk for developing advanced prostate cancer. Fifty-eight men were randomly assigned to consume 1 of 3 protein isolates containing 40 g/d protein: 1) soy protein isolate (SPI+) (107 mg/d isoflavones); 2) alcohol-washed soy protein isolate (SPI-) (<6> 5.5 mmol/l were given ISP+ for 12 weeks. In this male study there was a significant increase in HDL cholesterol (HDL-C) and SHBG. Soy protein has a cholesterol lowering effect in both women and men. These studies suggest that this effect is independent of isoflavones. Soy protein also reduces SHBG levels in both sexes.
3.Soy lowers DHT and decreases the DHT/Testosterone ratio.
J Nutr. 2005 Mar;135(3):584-91. Links
Soy protein isolates of varying isoflavone content exert minor effects on serum reproductive hormones in healthy young men.Dillingham BL, McVeigh BL, Lampe JW, Duncan AM.
Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Inverse associations between soy and prostate cancer and the contribution of hormones to prostate cancer prompted the current study to determine whether soy protein could alter serum hormones in men. Thirty-five men consumed milk protein isolate (MPI), low-isoflavone soy protein isolate (SPI) (low-iso SPI; 1.64 +/- 0.19 mg isoflavones/d), and high-iso SPI (61.7 +/- 7.35 mg isoflavones/d) for 57 d each in a randomized crossover design. Twenty-four-hour urine samples indicated that urinary isoflavones were significantly increased by the high-iso SPI relative to the low-iso SPI and MPI. Serum collected on d 1, 29, and 57 of each treatment revealed that dihydrotestosterone (DHT) and DHT/testosterone were significantly decreased by the low-iso SPI [9.4% (P = 0.036) and 9.0% (P = 0.004), respectively] and the high-iso SPI [15% (P = 0.047) and 14% (P = 0.013), respectively], compared with the MPI at d 57. Other significant effects included a decrease in testosterone by the low-iso SPI relative to the MPI (P = 0.023) and high-iso SPI (P = 0.020) at d 29; an increase in dehydroepiandrosterone sulfate by the low-iso SPI relative to the MPI at d 29 (P = 0.001) and relative to the MPI (P = 0.0003) and high-iso SPI (P = 0.005) at d 57; and increases in estradiol and estrone by the low-iso SPI relative to the MPI at d 57 (P = 0.010 and P = 0.005, respectively). In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone with minor effects on other hormones, providing evidence for some effects of soy protein on hormones. The relevance of the magnitude of these effects to future prostate cancer risk requires further investigation.
So, soy protein isolate consumption (with varying levels of isoflavones, I believe) decreases androgen receptor expression, mildly reduce DHT and the DHT to testosterone ratio, and assists with raising SHBG levels while having positive effects on lipoprotein and cholesterol levels.
The additional benefit to prostate health is quite convincing, as well. I really think that soy products (not necessarily what you'll find at your convenience store) should be a part of the diet of every sufferer of male pattern baldness.
Any additional input would be appreciated. I do know that fermented soy is safer, but I really don't know what affect the fermenation process has on isoflavone levels or if it degrades the soy protein in any way.
