Soy Isoflavones

CautionSuggested

2 studies · 2 recommendations

Last updated: February 1, 2026

Soy Isoflavones – Benign Prostatic Hyperplasia

Caution1 studies

Soy isoflavones show marginal benefit for BPH urinary symptoms over 12 months

A double-blind RCT found only slight superiority of 40mg daily soy isoflavones over placebo for lower urinary tract symptoms in BPH. While the supplement was safe and well-tolerated, benefits were marginal rather than clearly significant, suggesting isoflavones may be considered but should not replace standard care.

Evidence

Isoflavones in treating watchful waiting benign prostate hyperplasia: a double-blinded, randomized controlled trial

Authors: Ho, S, Hui, E, Li, H, Wong, ELY, Wong, WCW, Woo, J, You, JH

Published: January 1, 2012

In this 12-month double-blind, randomized, placebo-controlled trial of 176 men with BPH in Hong Kong, participants received either 40mg daily soy isoflavones or placebo. Peak urine flow rate (Qmax) showed marginal difference between groups (p=0.055) from months 6-12. The incomplete bladder emptying subscore in International Prostate Symptoms Scores (IPSS) reached borderline statistical significance (p=0.05) during the same period. The general health domain of SF-36 quality of life showed significant improvement in the isoflavone group versus placebo from baseline to 12 months (p=0.02). Both groups showed within-group improvements in Qmax, post-void residual volume, IPSS, and SF-36 scores. Isoflavones demonstrated excellent tolerability with no significant adverse effects on liver function, renal function, testosterone, or prostate-specific antigen levels.

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Suggested1 studies

Soy isoflavones may modestly improve urinary symptoms in BPH

Soy isoflavones at 40 mg daily showed slight improvements in urinary flow and symptom scores compared to placebo over 12 months. The supplement was well-tolerated with an excellent safety profile, though benefits were marginal. May be considered as a complementary approach for men with mild lower urinary tract symptoms under watchful waiting.

Evidence

Isoflavones in treating watchful waiting benign prostate hyperplasia: a double-blinded, randomized controlled trial

Authors: Ho, S, Hui, E, Li, H, Wong, ELY, Wong, WCW, Woo, J, You, JH

Published: January 1, 2012

In this double-blind, randomized controlled trial of 176 men with BPH conducted over 12 months, participants received 40 mg daily of soy isoflavones (Soylife 40) or placebo. Peak urine flow rate (Qmax) showed marginal difference between groups from months 6-12 (p=0.055). The incomplete emptying subscore of the International Prostate Symptoms Score (IPSS) reached statistical significance (p=0.05) between months 6-12. The general health domain of SF-36 quality of life showed significant improvement in the isoflavone group from baseline to 12 months (p=0.02). Both liver and renal function safety profiles remained normal. Isoflavones demonstrated excellent tolerability throughout the study period.

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