Saw Palmetto

Saw Palmetto is a supplement which is derived from the fruit of the plant Serenoa repens. The supplement (saw palmetto) has a caloric value, as it is a concoction of fatty acids.

The fatty acids in question have the ability to block an enzyme that converts testosterone into dihydrotestosterone (DHT), the latter of which is a more androgenic form and can cause hairloss in the genetically susceptible.

Its effects on DHT production have also led to saw palmetto being used for benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS) in men. Some studies have shown positive results, but larger and more well-designed studies have brought its efficacy into question.

While the active compound(s) are not yet known, it is known that they exist in what is known as the 'liposterolic' fraction of the fruits. If using saw palmetto choose a product that discloses the percentage of the supplement which is this fraction.

Supplementation of saw palmetto tends to be in the range of 160-320 mg, taken once daily, of a product which is 80-90% liposterolic compounds by weight. While it is not confirmed if saw palmetto needs to be taken with food due to the fat soluble nature of this fraction it is advised.

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects saw palmetto has on your body, and how strong these effects are.

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The more evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Symptoms of Benign Prostatic Hyperplasia	Minor	- See all 7 studies	Smaller, shorter trials have noted some effect, but larger, longer trials have noted no effect. The most recent Cochrane meta-analysis also notes no effect.
	DHT	-	- See study
	Prostate Specific Antigen		Low See all 4 studies	While observational data suggests a decrease, trials have found no change in PSA levels.
	Testosterone	-	Very High See 2 studies
	Quality of Life	Notable	Moderate See 2 studies
	Hair Regrowth	Minor	- See study	Saw palmetto usage over two years (320mg) appears to increase hair growth on the crown in 38% of users with male pattern baldness, a response rate that was less than 1mg finasteride (benefiting 66% of users and also improving hair growth in the frontal region).
	Sexual Function	Minor	Low See all 4 studies	While observational and smaller interventional studies have found some effect, larger and longer trials have not.

Studies Excluded from Consideration

• Confounded with β-sitosterol and B-vitamins^[1]

• Confounded with astaxanthin source^[2]

• Confounded with selenium and lycopene^[3]