Saw palmetto (cancer treatment)

ALSO KNOWN AS: Serenoa repens, Sabal serrulatum, Permixon

DEFINITION: Saw palmetto (Serenoa repens) is a small fan palm native to the Atlantic and Gulf coastal plains that can be found as far inland as southern Arkansas. The olive-sized fruit of this plant is enriched with fatty acids and phytosterols, and its extracts have been the subject of research for the treatment of certain cancers, especially prostate cancer.

Cancer treated or prevented:Prostate cancer

Delivery route: Oral by capsule

How this substance works: Used as an herbal supplement, saw palmetto is considered to be safe, effective, and relatively inexpensive. It enjoys widespread use in the United States, but it is also popular in Germany and France for the treatment of prostate disorders.

Saw palmetto inhibits 5-alpha-reductase, an enzyme that converts testosterone into its most potent form, dihydrotestosterone (DHT). Its effects have been compared to finasteride (Proscar), which is a prescription drug that results in the shrinkage of an enlarged prostate, a condition called benign prostatic hyperplasia (BPH). While studies of the efficacy of saw palmetto are somewhat inconsistent, it appears that saw palmetto largely lacks the adverse side effects of Proscar, such as decreased libido and gastrointestinal irritation. The most studied form is Permixon, which is made by using hexane as a solvent in the extraction process of the sterols and fatty acids found in the dried fruits of the saw palmetto berry. Other mixtures include ethanol, methanol, or, less commonly, nettle root or pumpkin seed oils. Although the extract is much studied, it is not fully understood what its active components are, but phytosterols and fatty acids seem to be the most proficient at treating symptoms.

Similarly, the mechanism by which saw palmetto actually works is still being studied. Some suggest that it acts as an anti-inflammatory, blocks the chemical conversion of testosterone to DHT, or promotes prostate epithelial involution. Whichever is correct, studies have shown that saw palmetto relieves symptoms caused by prostate disorders, including decreased urine stream and flow, post-voidance dribbling, overflow incontinence, and excessive retention of urine in the bladder. Relief of prostate swelling aids a return to sexual function, which also contributes to the popular use of saw palmetto among older men.

Not all studies agree on the therapeutic efficacy of saw palmetto; a double-blind, randomized study by Dr. Stephen Bent of the University of California, San Francisco, and his coworkers that was funded by the National Institutes of Health (NIH) and the National Center for Complementary and Alternative Medicine (NCCAM) found that saw palmetto was no more effective in reducing symptoms associated with BPH than a placebo. According to NCCAM, another study that it partially funded published results in 2011 that corroborated that earlier null association. These studies raised the question whether it was a medically useful substance.

As the twenty-first century progressed and more studies were performed on the efficacy of saw palmetto, results remained mixed. Studies clearly showed saw palmetto had anti-inflammatory and anti-androgenic properties. Supplementation with saw palmetto decreased hormone levels that led to prostate cancer. Results indicated that while saw palmetto alleviated many symptoms related to cancers, its ability to prevent or treat cancer could not be proven. One important finding of studies found that saw palmetto could increase the radiation sensitivity of prostate cells, and patients undergoing radiation were advised to avoid its use.

Overall, the Moores Cancer Center of the Medical Center of the University of California, San Diego, has stated that “this treatment modality is thought to manage symptoms of cancer, side effects from conventional therapies and/or control pain.” Researchers warn, however, that saw palmetto should be used as a supplement to cancer treatment, not in place of standard therapy.

Side effects: Adverse side effects are reported to be mild and infrequent, differing little from those reported after placebo use. Reports indicate that saw palmetto can cause gastrointestinal distress, but this can largely be alleviated by taking saw palmetto with food. Various other side effects have been noted, but it is unclear whether saw palmetto intake caused those. Saw palmetto may also enhance the effectiveness of blood thinners, raising the risk of bleeding.

Bibliography

Bone, Kerry, and Simon Mills. Principles and Practice of Phytotherapy: Modern Herbal Medicine. 2nd ed. London: Elsevier, 2013.

“Herbal Supplements and Heart Medicines May Not Mix.” Mayo Clinic, 4 Nov. 2022, www.mayoclinic.org/healthy-lifestyle/consumer-health/in-depth/herbal-supplements/art-20046488. Accessed 15 June 2024.

Moyad, Mark A. Complementary & Alternative Medicine for Prostate and Urologic Health. New York: Springer, 2014.

“Prostate Cancer, Nutrition, and Dietary Supplements (PDQ®)–Patient Version.” National Cancer Institute, 8 May 2024, www.cancer.gov/about-cancer/treatment/cam/patient/prostate-supplements-pdq. Accessed 15 June 2024.

“Saw Palmetto.” Memorial Sloan Kettering Cancer Center, 16 Oct. 2023, www.mskcc.org/cancer-care/integrative-medicine/herbs/saw-palmetto. Accessed 15 June 2024.

“Saw Palmetto.” National Center for Complementary and Integrative Health, www.nccih.nih.gov/health/saw-palmetto. Accessed 15 June 2024.

Sudeep, H.V., Thomas, J.V., and Shyamprasad, K. "A Double Blind, Placebo-Controlled Randomized Comparative Study on the Efficacy of Phytosterol-Enriched and Conventional Saw Palmetto Oil in Mitigating Benign Prostate Hyperplasia and Androgen Deficiency." BMC Urology, vol. 20, 2020, p. 86. doi.org/10.1186/s12894-020-00648-9. Accessed 15 June 2024.