Saw palmetto (serenoa repens) is one of the top 10 supplements taken by men to help optimize health. A dwarf palm native to the West Indies and Southeastern United States, saw palmetto produces oblong, maroon-colored berries that are frequently used for medicinal purposes. 

Today saw palmetto is popularly used by men with prostate concerns, but traditionally, it was used by both men and women of indigenous cultures for urinary complaints and to help increase testicular function and breast size. It has also been used to help reduce indigestion and to improve sleep. Women who are pregnant or who are breastfeeding should not take saw palmetto.

Saw Palmetto: Mechanism of Action

Saw palmetto inhibits 5a-reductase, an enzyme that is required to convert testosterone to dihydrotestosterone (DHT). Its extracts are ~90% fatty acids and are rich in saturated medium-chain fatty acids known as laurate and myristate. Frequently taken with prescription medications, saw palmetto has a low likelihood of reacting, according to a 2017 study. 

Proponents claim that the Saw Palmetto has the following benefits. 

Saw Palmetto and Hair Growth

As men age and hormone levels change, hair loss, medically referred to as male androgenetic alopecia (AGA), is common. For many men, this is a significant problem and may cause embarrassment or self-esteem issues. Popular medications, such as minoxidil and finasteride (Propecia), have been FDA approved for hair growth. The medication finasteride specifically inhibits 5a-reductase, the enzyme that blocks the conversion of testosterone to dihydrotestosterone. Saw palmetto works similarly.

A 2002 double-blind placebo-controlled study evaluated men with hair loss. The men in the study had mild-to-moderate age-related hair loss. By the end of the study, 60 percent of the men who took saw palmetto observed improvement in hair density. 

A 2012 study compared saw palmetto to the popular hair-growing FDA-approved drug finasteride. While both groups noticed an improvement in hair growth, the finasteride-consuming group experienced slightly better results than those who took saw palmetto. However, for those who want a more natural approach, saw palmetto if commonly considered and taken. 

A 2016 study affirmed the usefulness of oral saw palmetto in preventing hair loss while also testing a topical saw palmetto formula. The researchers concluded that topical application of saw palmetto is a suitable alternative for men who do not want to take prescription medications for hair loss. In a prior article, I discussed other natural approaches for those who are concerned about hair loss.

Saw Palmetto and Testosterone Levels 

As men age, testosterone levels naturally decrease. Lower levels of testosterone have been associated with fatigue, impotence, weight gain, reduced libido, and reduced muscle strength. Achieving a normal weight, consuming a low-sugar diet, and doing routine exercise can help one improve their testosterone levels. 

Frequently, men will consult with their physician regarding symptoms which may be due to low testosterone. A simple blood test can help identify those at risk. Sometimes, a doctor will recommend testosterone replacement, if appropriate. In my experience, many men seek a natural approach to improving testosterone, which has been discussed in a prior article.

A 2008 study showed that a saw-palmetto-containing supplement, which also contained astaxanthin, could help increase total testosterone levels in test subjects. The same study also showed a reduction in DHT, the mechanism by which hair growth is stimulated. 

However, a small study from 1988, which lasted only 30 days, did not show benefit in testosterone levels. It is likely that the time frame in which the saw palmetto was tested was too short. More studies are needed before a final conclusion can be made. 

Saw Palmetto and Prostate Health 

The prostate gland is crucial to a man’s health. In fact, the word itself is Greek in origin and defined as “one standing before” or “protector”. The prostate is positioned between the bladder and the colon. Its main function is to secrete a clear, alkaline fluid, which helps in the transportation of sperm during ejaculation. The alkalinity helps to neutralize the acidity of the vaginal canal, protecting sperm and increasing the chance for a sperm to fertilize an egg, allowing the cycle of life to go on. 

Two common prostate problems that men face include Benign Prostate Hyperplasia (BPH) and, more seriously, prostate cancer. 

Benign Prostate Hyperplasia

As men age, many will experience symptoms related to an enlarging prostate, a condition doctors call BPH or benign prostatic hyperplasia. Symptoms may begin around age 40, affecting up to 50 percent of men aged 60 and older. It is estimated that more than 2.5 million Americans (and millions more in Europe and Japan) rely on saw palmetto to help with prostate symptoms.

These symptoms include difficulty emptying the bladder, urine dribbling, reduced urine flow, and urinary frequency. There are prescription medications available to reduce symptoms, however, many prefer to try a more natural approach out of concern for side effects. Some of these medications include:

  • Alpha blockers – tamsulosin, doxazosin, terazosin, alfuzosin (side effects include low blood pressure, erectile dysfunction, headaches, and tremors)
  • 5-Alpha reductase inhibitors – finasteride, dutasteride (side effects include erectile dysfunction, and reduced libido)
  • Phosphodiesterase-5 inhibitors – tadalafil (side effects include stomach pain, stuffy nose, flushing, and dizziness)

Saw palmetto is an herbal medication that studies show may be helpful for some with enlarged prostate issues. In my experience with hundreds of men with symptoms of an enlarged prostate, half will benefit from saw palmetto while half do not notice any positive change. I have not seen anyone harmed by the use of this supplement.

Studies that Show Benefit

A 2001 study in Urology concluded, “Saw palmetto led to a statistically significant improvement in urinary symptoms in men with lower urinary tract symptoms compared with placebo. Saw palmetto had no measurable effect on the participants’ urinary flow rates. The mechanism by which saw palmetto improves urinary symptoms remains unknown….”

However, since 2001, we have learned more about how this herb works. A 2015 study, for instance, evaluated 165 men with enlarged prostate symptoms. The men were treated with 160 mg of saw palmetto daily. After six weeks, there was an improvement in urinary symptoms, leading researchers to conclude, “Saw palmetto extract capsules were safe and effective for the treatment of benign prostatic hyperplasia”

Further, a 2016 study in European Urology Focus of a highly concentrated saw palmetto extract also saw benefit. The researchers noticed those in the saw palmetto-consuming group had a reduction in their enlarged prostate-related symptoms. The benefits were similar to the effect seen in those taking the prescription medications tamsulosin and finasteride, which are used to treat symptoms of an enlarged prostate.

However, not all scientific studies have shown benefit.

Studies That Show No Benefit

Despite a 2002 study by Cochrane Database concluding that saw palmetto provided mild-to-moderate benefit in urinary symptoms and improved urine flow, a follow-up 2009 study showed saw palmetto by itself was not more effective than a placebo. 

Further, a 2006 study in the New England Journal of Medicine (NEJM) also did not notice a benefit in prostate symptoms in those men who took saw palmetto when compared to men who took a placebo. In this study of the 225 men, one half took the saw palmetto at a dose of 160 mg twice per day while the other half took the placebo, or sugar pill. The study lasted for one year. 

A 2012 study in JAMA compared 320 mg of saw palmetto to a placebo pill in 369 men. At the end of the study, there was no significant difference in symptoms in the men who took saw palmetto versus those who took the placebo. 

A 2017 study in the Journal of Alternative Complementary Medicine suggested that the overall evidence shows that saw palmetto could be beneficial within a naturopathic approach, even if part of the benefit was a placebo effect. 


Prostatitis occurs when there is inflammation present. Sometimes this is caused by a bacterial infection. 

A 2017 study from China evaluated 54 men with prostatitis. The researchers saw an improvement in urinary-related symptoms in those who took the saw palmetto extract. However, it is important to note that if you have been diagnosed with prostatitis, you should follow the recommendations of your physician. 

Combination Herbal Therapy

For those who do not notice satisfactory benefit from saw palmetto alone, a combination herb may be something to consider. There are studies that show that saw palmetto when taken in combination with selenium and lycopene, is more effective than when saw palmetto is taken alone. 

A 2011 study showed that the combination was better at reducing symptoms of an enlarged prostate when compared to taking only saw palmetto. This was echoed by a 2013 study in Current Medicinal Chemistry which found that lycopene-selenium taken with saw palmetto suppressed endothelial growth factor (EGF) and vascular endothelial growth factor (VEGF), both of which cause the prostate gland to grow in size. They concluded that the combination therapy had advantages over the singular use of saw palmetto. 

A 2016 study also confirmed the benefit of pairing prostate-support supplements with saw palmetto. The mix likely provides a synergistic effect that helps optimize prostate health.

Lastly, a 2019 study in BMC Complementary and Alternative Medicine also saw improvement in prostate symptoms when a phytosterol and saw palmetto were used in combination as compared to saw palmetto used on its own.

Dual Therapy Using Nature and Medicine

A 2014 study in Prostate randomized study evaluated 225 men aged 55 to 80 who had prostate symptoms. One third of the participants received saw palmetto/lycopene and selenium, another third were given the medication tamsulosin, and the last group was given the combination supplement and the prescription drug tamsulosin. After 12 months, the researchers found that those given the supplement along with prescription medication did the best. 

There is also evidence that those who take saw palmetto, in addition to the prescription medication finasteride, experience additional benefit. It is always important to consult with your physician before adding a supplement to your medical regimen. 

Prostate Cancer

Prostate cancer can affect up to one in six men during their lifetime. The majority of men with prostate cancer will not die from their cancer. Despite this, living a healthy lifestyle and making sound choices may be beneficial to staying well. 

A 2001 study showed that saw palmetto could prevent growth of cancer cells in the laboratory, while a later study in 2006 concluded that use of saw palmetto was not associated with prostate cancer risk. 

A 2016 study evaluated men with prostate cancer who were undergoing radiation treatment. The men consumed a dose of 960 mg of saw palmetto for 22 weeks, and no negative side effects were noted. However, there was also no significant difference realized in prostate-related symptoms in those who took the saw palmetto vs the placebo. 

How Can Saw Palmetto Help?

The body of studies tells us that saw palmetto will not help reduce the risk for prostate cancer. However, there is more evidence that it can be beneficial in those desiring to increase hair growth and in those men trying to reduce symptoms from an enlarged prostate. While experiences differ, there seem to be no damaging side effects for those who try it. In addition, when taken with prescription medications for prostate health, a synergistic effect may be realized. 


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