Isoflavones in Treating Watchful Waiting Benign Prostate Hyperplasia: A Double-Blinded,Randomized Controlled Trial

Abstract

Objectives:

This study aims to determine the efficacy and safety of soy isoflavones in controlling the symptoms and signs of lower urinary tract symptoms due to benign prostate hyperplasia (BPH).

Design:

This was a prospective, randomized, double-blind, placebo-controlled pilot study.

Setting:

This trial was conducted at two hospitals in Hong Kong between May 2006 and September 2007.

Participants:

One hundred and seventy-six (176) participants diagnosed with BPH were recruited from outpatient clinics. Participants with lower urinary tract symptoms were recruited through newspaper and radio interviews, posters placed at government outpatient clinics, and a public seminar offered by the investigators.

Interventions:

Participants were randomly assigned to either intervention (40 mg of isoflavones daily from Soylife 40) or placebo groups in a double-blind fashion.

Main outcome measures:

The primary outcome parameter of peak urine flow rate and the second outcome parameters of postresidual urine volume, lower urinary tract symptoms, testosterone, prostate-specific antigen, quality of life, diet, and safety profile (liver and renal function) were collected. All parameters were assessed at baseline, 6 months, and 12 months in a 12-month study period except testosterone, prostate-specific antigen, and safety profile, which were assessed at baseline and at 12 months.

Results:

The peak urine flow rate (Qmax), postresidual urine volume, International Prostate Symptoms Scores (IPSS), and 36-Item Short Form Health Survey (SF-36) significantly improved from baseline to the 12th month within both groups. However, when compared between groups, Qmax (p=0.055) and incomplete emptying subscore in IPSS (p=0.05) were marginally/statistically different between the two groups from the 6th to the 12th months, in addition to the general health domain of SF-36 from the baseline to 12th month (p=0.02) and from the 6th month to the 12th month (p=0.055). Isoflavones were generally safe and well tolerated.

Conclusions:

This randomized control pilot study showed only slight superiority of isoflavones over placebo over 12 months with otherwise surprising beneficial effects in both groups. Tolerability of isoflavones was excellent; thus it has laid foundations for further studies of isoflavones in BPH with focus on dosage and possible specificity of the effect.

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References

Lee

, Cockett

, Cussenot

et al. Regulation of prostate growth. Proceedings of the Fifth International Consultation on Benign Prostatic Hyperplasia. Birmingham, UK: Health Publications, Ltd., 2001; 79–106.

McNeal

. Origin and evolution of benign prostatic enlargement. Invest Urol, 1978; 15:340.

Dreikorn

. Complementary and alternative medicine in urology. BJU Int, 2005; 96:1177–1184.

Chan

, Elkin

, Silva

et al. Total and specific complementary and alternative medicine use in a large cohort of men with prostate cancer. Urology, 2005; 66:1223–1228.

Lee

, Chang

, Jacobs

et al. Complementary and alternative medicine use among men with prostate cancer in 4 ethnic populations. Am J Public Health, 2002; 92:1606–1609.

Wong

, Wong

, Donnan

. Prevalence and determinants of the use of traditional Chinese medicine in Hong Kong. Asia Pac J Public Health, 1995; 8:167–170.

Tacklind

, MacDonald

, Rutks

, Wilt

. Serenoa repens for benign prostatic hyperplasia. Cochrane Database of Systematic Reviews, 2009; 2:CD001423.

Wilt

, MacDonald

, Ishani

et al. Cernilton for benign prostatic hyperplasia. Cochrane Database Syst Rev, 2000; 2:CD001042.

Wilt

, Ishani

, MacDonald

et al. Beta-sitosterols for benign prostatic hyperplasia. Cochrane Database Syst Rev, 2002; 2:CD001043.

10.

Wilt

, Ishani

. Pygeum africanum for benign prostatic hyperplasia. Cochrane Database Syst Rev, 2002; 1:CD001044.

11.

Wong

, Lau

, Leung

et al. The association between isoflavone and lower urinary tract symptoms in elderly men. Br J Nutr, 2007; 98:1237–1242.

12.

Evans

, Griffiths

, Morton

. Inhibition of 5 alpha-reductase in genital skin fibroblasts and prostate tissue by dietary lignans and isoflavonoids. J Endocrinol, 1995; 147:295–302.

13.

Keung

. Dietary estrogenic isoflavones are potent inhibitors of beta-hydroxysteroid dehydrogenase of P. testosteronii. Biochem Biophys Res Commun, 1995; 215:1137–1144.

14.

Campbell

, Kurzer

. Flavonoid inhibition of aromatase enzyme activity in human preadipocytes. J Steroid Biochem Mol Biol, 1993; 46:381–388.

15.

Matzkin

, Soloway

. Immunohistochemical evidence of the existence and localization of aromatase in human prostatic tissues. Prostate, 1992; 21:309–314.

16.

Wang

, Sathyamoorthy

, Phang

. Molecular effects of genistein on estrogen receptor mediated pathways. Carcinogenesis, 1996; 17:271–275.

17.

Adlercreutz

, Markkanen

, Watanabe

. Plasma concentrations of phyto-oestrogens in Japanese men. Lancet, 1993; 342:1209–1210.

18.

Morton

, Chan

, Cheng

et al. Lignans and isoflavonoids in plasma and prostatic fluid in men: Samples from Portugal, Hong Kong, and the United Kingdom. Prostate, 1997; 32:122–128.

19.

Muir

, Nectoux

, Staszewski

. The epidemiology of prostatic cancer: Geographical distribution and time-trends. Acta Oncol, 1991; 30:133–140.

20.

Jacobsen

, Knutsen

, Fraser

. Does high soy milk intake reduce prostate cancer incidence? The Adventist Health Study (United States) Cancer Causes Control, 1998; 9:553–557.

21.

American Urological Association. Guideline on the Management of Benign Prostatic Hyperplasia[updated 2003]www.auanet.org/content/guidelines-and-quality-care/clinical-guidelines.cfm?sub=bph. 2009 May 8.

22.

Nickel

, Fradet

, Boake

et al. Efficacy and safety of finasteride therapy for benign prostatic hyperplasia: Results of a 2-year randomized controlled trial (the PROSPECT study). PROscar Safety Plus Efficacy Canadian Two year Study. CMAJ, 1996; 155:1251–1259.

23.

Chute

, Panser

, Girman

et al. The prevalence of prostatism: A population based survey of urinary symptoms. J Urol, 1993; 150:85–89.

24.

Shi

, Xie

, Gang

et al. Effect of saw palmetto soft gel capsule on lower urinary tract symptoms associated with benign prostatic hyperplasia: A randomized trial in Shanghai, China. J Urol, 2008; 179:610–615.

25.

Cassidy

. Potential risks and benefits of phytoestrogen-rich diets. Int J Vitam Nutr Res, 2003; 73:120–126.

26.

Griffiths

, Morton

, Denis

. Certain aspects of molecular endocrinology that relate to the influence of dietary factors on the pathogenesis of prostate cancer. Eur Urol, 1999; 35:443–455.

27.

Kumar

, Cantor

, Allen

et al. The specific role of isoflavones in reducing prostate cancer risk. Prostate, 2004; 59:141–147.

28.

Lam

, Gandek

, Ren

et al. Tests of scaling assumptions and construct validity of the Chinese (HK) version of the SF-36 Health Survey. J Clin Epidemiol, 1998; 51:1139–1147.

29.

Hebert

, Ockene

, Hurley

et al.

Development and testing of a seven-day dietary recall. Dietary Assessment Working Group of the Worcester Area Trial for Counseling in Hyperlipidemia (WATCH)

J Clin Epidemiol, 1997; 50:925–937.

30.

Abbott Laboratories. HYTRIN—terazosin hydrochloride tablet. North Chicago, IL, 2009[updated 2009]www.rxabbott.com/u4_prescribing_info.cfm. 2009 May 8.

31.

Michel

, Goepel

. Treatment satisfaction of patients with lower urinary tract symptoms: Randomised controlled trials vs. real life practice. Eur Urol, 2000; 38:40–47.

32.

de la Rosette

, Madersbacher

, Alivizatos

et al. Guidelines on Benign Prostatic Hyperplasia. European Association of Urology. 2006. www.urotoday.com/prod/pdf/eau/BPH_August_2004.pdf. 2009 May 8.