Saw palmetto is one of the most widely used natural supplements worldwide, with sales totaling over $700 in 2010 alone (over $200 million in the United States) and is consistently ranked in the top 15 botanical supplements in terms of sales volume.
It's most common use is for the treatment of BPH (benign prostatic hyperplasia) symptoms (e.g. trouble urinating).
Less commonly, it has been used to treat hair loss. Overall, research evaluating its effectiveness is mixed and contradictory.
Some studies have shown some benefit for reversing hair loss, but only in certain situations. Specifically, it appears to only be potentially effective in treating androgenic alopecia, also known as male (or female) pattern baldness.
What Is Androgenic Alopecia?
Androgenic alopecia is a form of hair loss that is related to hormones, known as androgens. Androgens play an important role in both males and females, regulating hair growth, sex drive, and sexual development.
The androgen most-well associated with effects on hair growth is called dihydrotestosterone (DHT). Increased levels of DHT in hair follicles can lead to:
- Shorter cycle of hair growth
- Shorter hair growth
- Thinner strands of hair
- Delay in new hair growth after hair is shed
Studies show a reduction in DHT in hair follicles can reduce hair loss. A prescription drug, Proscar (finasteride), is FDA approved for the treatment of androgenic alopecia and works by reducing DHT levels.
How Saw Palmetto Works
Saw palmetto has a wide variety of effects, but what we will focus on here is its mechanism behind a potential reduction in hair loss.
Studies show that saw palmetto may have antiandrogen effects and, at least to some degree, inhibits an enzyme known as 5-alpha-reductase.
5-alpha-reductase is responsible for the conversion of testosterone to dihydrotestosterone (DHT).
Remember that high levels of DHT are associated with hair loss. Thus, a reduction in DHT may lead to less hair loss.
Since saw palmetto may inhibit 5-alpha-reductase, there would be less conversion of testosterone to DHT, which could potentially decrease hair loss.
Several studies have shown that saw palmetto works, at least somewhat, by this mechanism:
"SPSE [saw palmetto extract] effectively inhibits the enzyme that has been linked to BPH, and the amount of extract required for activity is comparatively low."
This mechanism of action is similar to how some prescription drugs work. Proscar (finasteride), which is mentioned in the section above, is a 5-alpha-reductase inhibitor.
It is important to point out that not all studies report that saw palmetto effectively reduces DHT to a significant degree and additional studies are needed to more clearly elucidate whether or not this is how saw palmetto works.
Saw Palmetto For Androgenic Alopecia
There is mixed and contradictory evidence for how effective saw palmetto is the treatment of hair loss. In studies that have shown benefit, it has only been specifically for androgenic-related hair loss.
It likely isn't effective if you are losing hair for other reasons. Its potential benefits for androgenic alopecia is likely due to the fact that saw palmetto has antiandrogenic effects, as discussed above.
Unfortunately, there haven't been many studies that have specifically evaluated the use of saw palmetto for hair loss, so there isn't much data to go on.
One study shows tested a combination of saw palmetto extract 200 mg plus beta-sitosterol 50 mg, taken twice daily.
Effectiveness was measured via subjective scores for hair quantity and hair quality in men. Sixty percent of the men studied reported benefits, which led the study to conclude:
"This study establishes the effectiveness of naturally occurring 5AR [5-alpha reductase inhibitors] against AGA [androgenic alopecia] for the first time, and justifies the expansion to larger trials."
Another study also found that saw palmetto was beneficial for hair loss, but was less effective, than Proscar. it concluded:
"We can summarize our results by observing that Serenoa repens [active constituent of saw palmetto] could lead to an improvement of androgenetic alopecia, while finasteride confirmed its efficacy. We also clinically observed, that finasteride acts in both the front area and the vertex, while Serenoa repens prevalently in the vertex."
Although preliminary studies have shown promise, more large, well-designed studies are necessary.
As discussed, there is mixed evidence on whether or not saw palmetto is effective in treating hair loss.
At the very least, we can say that may improve hair loss due to an excess of androgen (androgenic alopecia), but more studies are needed.
As with any drug or natural product, you should talk with your doctor before taking saw palmetto.
It generally is reported to be well tolerated, with side effects (e.g dizziness, headache, and gastrointestinal complaints such as nausea, vomiting, constipation, and diarrhea) most often being mild. It may interact with certain drugs (e.g., anticoagulants, birth control), so that is something to take into account as well.
Saw palmetto has mixed evidence for the treatment of androgenic alopecia (male or female pattern baldness). Saw palmetto may inhibit an enzyme known as 5-alpha-reductase, and lower levels of DHT, an androgen. Excess DHT is associated is hair loss. Some studies show positive effects, but it generally is not as effective as other treatments, such as Proscar (finasteride). More studies are needed to further understand the potential risk and benefits of using saw palmetto for hair loss.
- Proscar Prescribing Information. AccessFDA
- Determination of the potency of a novel saw palmetto supercritical CO2 extract (SPSE) for 5α-reductase isoform II inhibition using a cell-free in vitro test system. PubMed
- Comparative effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year study. PubMed
- A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. PubMed
- Botanical Bulletin On Saw Palmetto. American Botanical Council
- Leading Saw Palmetto Producer Reports That Consumers May Be Using Saw Palmetto Incorrectly in Support of Prostate Health. PRN News Wire