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Review Of The Most Commonly Used Herbal Supplements For “Prostate Enlargement”: Where Is The Evidence?
Mahdi Zangi, M.D., Michelle Kim, M.D., Reza Nabavizadeh, B.S., Maryam Yavari Bejestani, B.A., Shahin Tabatabaei, MD.
Massachusetts General Hospital, Boston, MA, USA.
BACKGROUND: Herbal supplements are widely used by patients with BPH, yet little is known about the efficacy of these products and their scientific evidence. We describe the ingredients of herbal supplements marketed for BPH and review its scientific evidence.
METHODS: We conducted a search of all Amazon products using the search term “prostate enlargement.” Out of the 85 products found, 41 were identified as herbal supplements claiming to relieve BPH symptoms. Information including product name, company, price, claimed effects, consumer satisfaction, active and inactive ingredients were extracted from each product. 2,400 pages of Google Scholar were used to research for evidence behind ingredients (4 pages per ingredient). We categorized scientific evidence for each ingredient into human (systematic reviews, randomized-control trials, cohorts, case-controls, epidemiology), animal, and in vitro (cellular/molecular) studies.
RESULTS: Out of 41 products, 34 (82.9%) were produced by American companies. The price per month of supply ranged from $2.63 to $319.98 (Median: $ 26.47). Less than half (46.3%) had a money back guarantee. Thirty-six products were reviewed by customers with satisfaction score ranging from 3.1 to 5 out of 5 (mean: 4.38± 0.55). 14 (34.1%) products did not even list ingredients on the nutrition fact table and therefore were excluded from this study because of lack of data. 11 (26.8%) products did not list inactive ingredients. The most commonly used ingredients were Saw palmetto (74.1%), zinc (74.1%), Lycopene (51.9%), β-Sitosterol (51.9%), Pygeum Africanum (44.4%), and Stinging Nettle (44.4%).
A total of 60 different ingredients were identified, out of which 10 showed clinical efficacy in human studies (8 RCTs, 1 systematic review, and 1 case-control). 9 showed benefits in animal study models and 1 product had ingredients with only molecular and in vitro evidence of efficacy. 35 ingredients had no scientific evidence and 5 had conflicting evidence. Out of the 27 products that listed their ingredients, 25 had at least one scientifically proven ingredient based on human studies. Only 1 product had an ingredient with systematic review level of evidence and all other 24 products had at least one ingredient with RCT level of evidence. One product had ingredients only shown to be effective based on animal studies. One product did not contain any ingredient known to be effective for BPH. For these 27 products, the average number of ingredients scientifically proven to be effective based on human, animal, and in vitro/molecular studies was 2.93 (±1.86), 1.3 (±1.44), and 0.07 (±0.27), respectively.
There was no statistically significant correlation between number of effective ingredients and monthly supply cost or consumer satisfaction.
CONCLUSIONS: Herbal supplements are widely available and heavily advertised to patients with BPH symptoms. They enjoy the lack of scrutiny and accountability that are mandatory for FDA-approved medical therapies. These products are quite diverse in their active and inactive ingredients with scant scientific evidence supporting their efficacy. Physicians, specially urologists, should be more familiar with these products given their widespread use and play a more active role in educating their patients in this regard.
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