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If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
What is saw palmetto?
Saw palmetto, also known as Serenoa repens or the American dwarf palm tree, is a plant native to the southeastern United States. Historically, it was an important plant in the culture of Native American tribes that lived in Florida and the lower Mississippi Valley (USDA, n.d.). The leaves were used to make bedding, housing, baskets, ropes, and other important items of daily life. The fruits were also important food sources and herbal medicines for the Seminoles and other tribes in that region (Oomah, 2000). The non-Native settlers also adopted saw palmetto berries as medicine to treat diseases of the reproductive organs, digestive issues, colds, and asthma.
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How does saw palmetto work?
Exactly how saw palmetto is supposed to work is not fully understood. Some researchers think that it can inhibit 5-alpha-reductase (5a-R), an enzyme that converts testosterone to dihydrotestosterone (DHT) (Di Silverio, 1998). DHT is a male sex hormone that’s more potent than regular testosterone. It has a wide range of functions in the body and plays an important role in male development, especially during puberty, including developing the penis, scrotum, testicles, and facial, body, and pubic hair. Unfortunately, it’s also been linked to male pattern baldness and benign prostatic hyperplasia (BPH), otherwise known as an enlarged prostate gland or benign prostatic hypertrophy. Reducing DHT levels is a way that some prescription BPH and hair loss medications (such as finasteride [brand name Propecia; see Important Safety Information]) work.
Saw palmetto and low testosterone
Testosterone, a male sex hormone, has a wide array of effects on the human body. It plays roles in maintaining your sex drive, bone mass, muscle mass, blood cell production, and sperm production. Levels of testosterone naturally drop over time. One large study from the National Institutes of Health (NIH) reported that low testosterone (also called “low T”) affected 20% of men in their 60s, 30% of men in their 70s, and 50% of men over 80 (Harman, 2001). Understandably, many men are looking for ways to keep their testosterone up.
Several supplements on the market that contain saw palmetto claim to boost testosterone. Because it’s thought to block 5a-R, the enzyme that takes testosterone and turns it into DHT, logic follows that it might be able to increase testosterone levels. How does this play out in real life, and can saw palmetto really boost testosterone levels?
One study tested a dietary supplement that combined both saw palmetto extracts and an antioxidant called astaxanthin (Angwafor, 2008). Levels of testosterone went up, and DHT went down after two weeks of taking the supplement. However, this study was not placebo-controlled, so it’s unclear if the supplement was really responsible for this increase in testosterone. Another study showed that the same supplement with doses of saw palmetto and astaxanthin decreased DHT when compared with placebo, but did not significantly increase testosterone (Anderson, 2014). Finally, an Italian study showed that, after 30 days of taking a saw palmetto extract, there was no change in testosterone (Casarosa, 1988).
Overall, saw palmetto doesn’t appear to increase testosterone levels. If you’re concerned about “low T,” talk to your healthcare provider. They can test your hormone levels and determine what treatment would be right for you.
Learn more about testosterone here.
Saw palmetto: uses, benefits, and side effects
Saw palmetto and benign prostatic hyperplasia (BPH)
Saw palmetto is especially popular for treating the symptoms of BPH, with over two million men taking it for this purpose (Bent, 2006). Men with BPH experience an unwelcome bundle of urinary problems, including straining, weak stream, retaining urine, going frequently (especially at night), and the sudden need to urinate. Healthcare providers refer to these symptoms as “lower urinary tract symptoms,” or LUTS. The risk of BPH increases as men age. Research published in the Journal of Urology estimates that half of men in their 50s and 90% of men in their 80s deal with BPH symptoms (Barry, 1984).
Despite its popularity, saw palmetto has not demonstrated in clinical trials that it works to treat BPH. Several large, high-quality trials have shown that it has no effect when compared with placebo (Barry, 2011; Bent, 2006). Also, a 2012 review of 32 randomized trials that included a total of over 5,000 patients with BPH showed that saw palmetto did not beat the placebo in urinary symptoms, urinary flow, or prostate size (Tacklind, 2012).
When it comes to BPH, saw palmetto simply doesn’t work. If you’re struggling with urinary symptoms or concerned about BPH, talk to your healthcare provider to see what tests and treatment options would be right for you.
Other “benefits” of saw palmetto
Saw palmetto is purported to work in a bunch of other health conditions. Let’s quickly walk through them.
- Prostate cancer: Saw palmetto is widely used by people dealing with prostate cancer, and over half of those using it believe that it will treat or cure their disease (Boon, 2003). The use of saw palmetto has not been shown to change the course of cancer (Memorial Sloan, 2017).
- Prostatitis: Saw palmetto has not been shown to work in treating prostatitis (inflammation of the prostate that causes pain and burning urination) (Kaplan, 2004).
- Hair loss: Male pattern baldness affects millions of men in the United States. It gets more common with age, as 30% experience it at age 30, 40% at age 40, and 50% at age 50 (Phillips, 2017). Saw palmetto hasn’t been tested very much to treat hair loss, but in a few small studies, it was shown to increase hair growth and density (Wessagowit, 2015; Prager, 2002). However, the scientific consensus is that there isn’t enough evidence to support its use (Murugusundram, 2009).
Learn more about prostate cancer here.
10 signs and symptoms of low testosterone
Side effects of saw palmetto
Saw palmetto is generally considered safe, with only mild side effects like headache, nausea, upset stomach, and dizziness (NCCIH, 2016). It doesn’t appear to interact with any other medications, but it’s primarily been studied in men. In women or children, the risks of saw palmetto are less clear.
Because of the hormonal effects of saw palmetto, don’t take saw palmetto while pregnant or breastfeeding. Stop taking saw palmetto two weeks before surgery—saw palmetto can theoretically have anticoagulant or antiplatelet effects that may make increase your bleeding risk (Ang-Lee, 2001).
As a dietary supplement, the FDA has not approved saw palmetto for any medicinal purpose. If you choose to take saw palmetto, please make sure to tell your health care provider and follow their medical advice.
- Anderson, M. L. (2014). Evaluation of Resettin® on serum hormone levels in sedentary males. Journal of the International Society of Sports Nutrition, 11, 43. doi: 10.1186/s12970-014-0043-x. Retrieved from https://jissn.biomedcentral.com/articles/10.1186/s12970-014-0043-x
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- Angwafor, F. & Anderson, M. L. (2008). An open label, dose response study to determine the effect of a dietary supplement on dihydrotestosterone, testosterone and estradiol levels in healthy males. Journal of the International Society of Sports Nutrition, 5, 12. doi: 10.1186/1550-2783-5-12. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/18700016
- Barry, M. J., Meleth, S., Lee, J. Y., Kreder, K. J., Avins, A. L., Nickel, J. C., et al. (2011). Effect of Increasing Doses of Saw Palmetto Extract on Lower Urinary Tract Symptoms: A Randomized Trial. JAMA, 306(12), 1344–1351. doi: 10.1001/jama.2011.1364. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/21954478
- Bent, S., Kane, C., Shinohara, K., Neuhaus, J., Hudes, E. S., Goldberg, H., et al. (2006). Saw Palmetto for Benign Prostatic Hyperplasia. New England Journal of Medicine, 354, 557–566. doi: 10.1056/NEJMoa053085. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/16467543
- Boon, H., Westlake, K., Stewart, M., Gray, R., Fleshner, N., Gavin, A., et al. (2003). Use of complementary/alternative medicine by men diagnosed with prostate cancer: prevalence and characteristics. Urology, 62(5), 849–853. doi: 10.1016/s0090-4295(03)00668-x. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/14624907
- Casarosa, C., Cosci di Coscio, M., & Fratta, M. (1988). Lack of effects of a lyposterolic extract of Serenoa repens on plasma levels of testosterone, follicle-stimulating hormone, and luteinizing hormone. Clinical Therapeutics, 10(5), 585–588. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/2485240
- Di Silverio, F., Monti, S., Sciarra, A., Varasano, P., Martini, C., Lanzara, S., et al. (1998). Effects of long-term treatment with Serenoa repens (Permixon®) on the concentrations and regional distribution of androgens and epidermal growth factor in benign prostatic hyperplasia. The Prostate, 37(2), 77–83. doi: 10.1002/(sici)1097-0045(19981001)37:23.0.co;2-i. Retrieved from https://pubmed.ncbi.nlm.nih.gov/9759701/
- Harman, S. M., Metter, E. J., Tobin, J. D., Pearson, J., & Blackman, M. R. (2001). Longitudinal Effects of Aging on Serum Total and Free Testosterone Levels in Healthy Men. The Journal of Clinical Endocrinology & Metabolism, 86(2), 724–731. doi: 10.1210/jcem.86.2.7219. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/11158037
- Kaplan, S. A., Volpe, M. A., & Te, A. E. (2004). A Prospective, 1-Year Trial Using Saw Palmetto Versus Finasteride in the Treatment of Category III Prostatitis/Chronic Pelvic Pain Syndrome. Journal of Urology, 171(1), 284–288. doi: 10.1097/01.ju.0000101487.83730.80. Retrieved from https://europepmc.org/article/med/14665895
- Memorial Sloan Kettering Cancer Center. (2017, September 11). Saw Palmetto. Retrieved from https://www.mskcc.org/cancer-care/integrative-medicine/herbs/saw-palmetto
- Murugusundram, S. (2009). Serenoa repens: Does it have any role in the management of androgenetic alopecia? Journal of Cutaneous and Aesthetic Surgery, 2(1), 31–32. doi: 10.4103/0974-2077.53097. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2840915/
- National Center for Complementary and Integrative Health (NCCIH). (2016, December 1). Saw Palmetto. Retrieved from https://nccih.nih.gov/health/palmetto/ataglance.htm
- Oomah, B. D. (2000). Herbs, Botanicals and Teas (Functional Foods and Nutraceuticals). CRC Press. Retrieved from https://books.google.com/books?id=Au1HLD7eyZQC&lpg=PA190&dq=hutchens 1973 saw palmetto&pg=PA190#v=onepage&q&f=false
- Phillips, T. G., Slomiany, W. P., & Allison, R. (2017). Hair Loss: Common Causes and Treatment. American Family Physician, 96(6), 371–378. Retrieved from https://www.aafp.org/afp/2017/0915/p371.html
- Prager, N., Bickett, K., French, N., & Marcovici, G. (2002). A Randomized, Double-Blind, Placebo-Controlled Trial to Determine the Effectiveness of Botanically Derived Inhibitors of 5-α-Reductase in the Treatment of Androgenetic Alopecia. The Journal of Alternative and Complementary Medicine, 8(2), 143–152. doi: 10.1089/acm.2002.8.143. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/12006122
- Tacklind, J. W., Macdonald, R., Rutks, I., & Wilt, T. J. (2012). Serenoa repens monotherapy for benign prostatic hyperplasia. Cochrane Library, 12. doi: 10.1002/14651858.CD001423.pub3. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22551330
- The development of human benign prostatic hyperplasia with age. (1984). The Journal of Urology, 132(3), 474–479. doi: 10.1016/s0022-5347(17)49698-4. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/6206240
- United States Department of Agriculture (USDA). (n.d.). Plant Guide: Saw Palmetto. Retrieved from https://plants.usda.gov/plantguide/doc/cs_sere2.docx
- Wessagowit, V., Tangjaturonrusamee, C., Kootiratrakarn, T., Bunnag, T., Pimonrat, T., Muangdang, N., et al. (2015). Treatment of male androgenetic alopecia with topical products containingSerenoa repensextract. Australasian Journal of Dermatology, 57(3), e76–e82. doi: 10.1111/ajd.12352. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/26010505