The Effect of Phytosterols on Quality of Life in the Treatment of Benign Prostatic Hyperplasia

Craig I. Coleman, Pharm.D., John H. Hebert, Pharm.D., Prabashni Reddy, Pharm.D.


Pharmacotherapy. 2002;22(11) 

In This Article

Abstract and Introduction

In the United States, phytosterols are available as over-the-counter dietary supplements and are promoted as a safe and natural way to maintain a healthy prostate. In men with benign prostatic hyperplasia (BPH), evidence suggests that the agents improve urologic symptoms and flow measures to a greater extent than placebo and to a similar extent as finasteride. The primary goal for treating men with BPH is to reduce lower urinary tract symptoms and increase quality of life (QOL). Therefore, QOL has become an increasingly important end point in clinical trials. We reviewed all seven studies that determined the effect of phytosterols on QOL in patients with BPH. All trials assessed QOL with international prostate symptom score questions. Six studies found phytosterols to have beneficial effects on QOL; however, poor study design limits what can be learned from these evaluations. Most studies included a limited number of patients, and many were not placebo controlled. Since few of them evaluated the effect of phytosterols beyond 6 months, little evidence exists of the agents' long-term efficacy in reducing symptomatology or increasing QOL. Finally, phytosterols have not been adequately compared with -blocking agents, one of the most widely administered and effective pharmacologic treatments of BPH. Larger studies comparing phytosterols with other treatments of BPH such as -blockers should be conducted. In addition, a consensus should be reached as to which questionnaires are best to evaluate potential changes in QOL after treatment of BPH.

Phytosterols are readily available over the counter as dietary supplements in the United States, and are promoted as a safe and natural way for men to maintain a healthy prostate.[1] In 1999 consumers in this country spent over $140 million on saw palmetto (Serenoa repens) alone.[2]Serenoa repens is a dwarf palm tree that grows in the southwest United States. Extracts of the plant contain a mixture of phytosterols such as -sitosterol, campesterol, and stigmasterol, as well as flavonoids and other compounds.[3] Phytosterols used to treat benign prostatic hyperplasia (BPH) are also extracted from Hypoxis rooperi (South African star grass). This extract contains -sitosterol, with lesser amounts of other sterols, and is marketed in Europe under brand names Harzol and Azuprostat.[3] Although both plant-derived extracts contain many phytosterols, -sitosterol often is considered the major active component.[3] The mechanism of action of phytosterols in BPH, although not well described, reportedly includes alterations in cholesterol metabolism; antiestrogenic, antiandrogenic, and antiinflammatory effects; and decreases in sex hormone-binding globulin.[1]

Phytosterols improved lower urinary tract symptoms (LUTS) and urinary flow measures in numerous clinical trials.[1,4] According to a systematic review of 18 randomized, controlled studies of S. repens (alone or in combination with other phytotherapeutic agents) of 4-48 weeks' duration, compared with placebo, men treated with S. repens had decreases in LUTS scores and nocturia and greater improvement in peak urine flow.[1] Compared with finasteride, men treated with S. repens had similar improvements in LUTS scores and peak urine flow rates.[1]

-Sitosterols also are efficacious in the treatment of BPH, improving urinary symptoms and flow measures in four placebo-controlled clinical trials.[4] To date, the efficacy of phytosterols has not been compared with that of -blocking agents in the treatment of BPH.[1,4]

The primary goals of treating BPH are to reduce LUTS and improve quality of life (QOL).[5] Quality of life includes physical, psychologic, and social domains and is a subjective perception of how a disease or treatment affects health status.[6] Despite frequent reports of use of herbal products to promote general health and well-being and to increase QOL, studies mainly focused on clinical outcomes, with QOL evaluated only occasionally as a secondary end point.[7] The American College of Clinical Pharmacy published a white paper that called for additional research on herbal products, listing QOL evaluations as an area in which further investigation is necessary.[8]

Quality of life was evaluated as a secondary end point in a number of clinical trials of -blockers and finasteride, the most efficacious medical treatments for BPH.[9,10] Since they applied several QOL instruments, comparisons among drugs are difficult.[9] Evidence shows, however, that -blockers excel over finasteride, with earlier onset of response, greater improvements in QOL, and fewer sexual side effects.[9] The combination of finasteride with an -blocker (terazosin, doxazosin) appears to improve QOL to a similar extent as the -blocker alone, but to a greater extent than finasteride alone or placebo.[11,12] Finasteride's effect on QOL was most promising in patients with large prostate.[9]


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