Last updated by Dr Sarah Brewer on
Saw palmetto is a herbal medicine used to support prostate health and improve lower urinary tract symptoms (known as LUTS) in men. As a result, Saw palmetto is popularly known as the male plant catheter or the prostrate palm (pun intended) due to its low-growing habit. Saw palmetto is also used to help treat polycystic ovary syndrome (PCOS) in women.
- What is Saw palmetto?
- Saw Palmetto Honey
- Saw palmetto berries for prostate health
- Saw palmetto and prostate health
- How does Saw palmetto work?
- Saw palmetto and DHT
- Saw palmetto and oestrogen
- Saw palmetto as an alpha-blocker
- Other actions of Saw palmetto
- Saw palmetto and prostatitis
- Saw palmetto and prostate Cancer
- Saw palmetto and hair loss
- Saw palmetto for women
- Saw palmetto dose
- Saw palmetto safety
What is Saw palmetto?
The Saw palmetto is an attractive, small palm native to the West Indies and the Atlantic coast of North America. It grows from six to 10 feet high and has multiple fan-shaped leaves that are two feet or more in length.These leaves have sharp, spiny teeth on their edge, like those of a saw, which is how the tree gets its common name.
Botanically, the Saw palmetto has two names: Sabal serrulata and Serenoa repens. It’s also referred to as Serenoa serrulata or Sabalis serrulatae which, not surprisingly, can lead to confusion.
In some cases, men have taken both a Sabal supplement and one containing Serenoa. Although this is unlikely to be harmful, it is unnecessarily expensive.
Saw palmetto’s medicinal benefits are obtained from the berries. Saw palmetto berry extracts are a traditional herbal medicine used to treat lower urinary tract symptoms in men.
Saw Palmetto Honey
Each dwarf palm bears from one to five densely branched sprays of flowers up to two feet long, each of which sets several thousand dark berries.
Saw palmetto flowers have a nutty, vanilla flavour that is a favourite among many species of wildlife, including black bears, white-tailed deer, raccoons, wild turkeys, fox and even tortoises.
The Saw palmetto’s ivory flowers have a powerful scent that attract over 300 species of insect, including honeybees who collect the pollen and nectar.
If you ever see Saw palmetto honey for sale, snap it up, as saw palmetto honey has a lovely flavour alongside its medicinal qualities.
Saw palmetto berries for prostate health
Saw palmetto berries are a rich source of fat-soluble sterols (such as ß-sitosterol, campesterol and stigmasterol) plus antioxidant polyphenols, including flavonoids. Saw palmetto berries are a traditional herbal medicine to improve symptoms caused by enlargement of the prostate gland (benign prostate hyperplasia, or BPH) and prostate inflammation (prostatitis).
BPH causes two types of male lower urinary tract symptoms: obstructive or voiding symptoms and irritative or filling symptoms.
The obstructive symptoms of BPH include:
• Hesitancy (difficulty starting to urinate)
• Straining (having to force urine out)
• A weak urinary stream
• Stopping and starting mid-flow
• Dribbling of urine after voiding
• Urinary retention (inability to completely empty the bladder)
The irritative symptoms of BPH include:
• Urgency (a sudden need to go to the toilet)
• Nocturia (waking to pass urine at night)
• Urinary discomfort
• Urinary incontinence
• A feeling of not having emptied the bladder fully.
Saw palmetto berry extracts are most effective against the irritative prostate symptoms, especially nocturia, which are often more troublesome than the obstructive symptoms.
Clinical trials have found that Saw palmetto usually takes around six weeks for benefits to become noticeable.
Saw palmetto and prostate health
More than 20 randomised, double-blind, placebo-controlled trials show that standardised extracts of Saw palmetto berries (providing 85% to 90% fatty acids and sterols) can relieve the symptoms of BPH, especially night-time urinary frequency (nocturia) which is typically reduced by 33% to 74% (versus 13% to 39% with placebo).
Some studies found Saw palmetto was as effective as prescribed medicines in treating prostate symptoms. In a trial involving over 1000 men with moderate symptoms of BPH, taking either Saw palmetto or the prescription-only drug, finasteride, reduced prostate symptoms by 38% over a 6 month period. In those taking Saw palmetto however, sexual function was not affected, while in those taking finasteride, sexual performance deteriorated significantly.
Another study compared Saw palmetto against the prescribed alpha-blocker drug, prazosin, in 45 men. At the end of the 12 week trial, flow rate and symptoms improved in both groups to a similar extent, although improvements in irritative symptoms were slightly less with Saw palmetto.
In a larger study, 103 men referred to a Korean hospital with bothersome BPH symptoms were all prescribed the alpha-blocker drug, tamsulosin, but half also received additional treatment with Saw palmetto at a dose of 320mg per day. At 6 months, and at 12 months, total prostate symptoms score showed a significantly greater improvement in the men taking both treatments than in those on the prescribed drug alone. Side effects were slightly higher in those taking the combination however (20% versus 16.9% with tamsulosin alone).
Another study randomised 225 men with BPH to receive either the drug, tamsulosin, or a combination natural therapy based on Saw palmetto plus lycopene and selenium, or both the drug and the Saw palmetto mix. Symptom improvement was significantly greater for the combination therapy than for either treatments alone at six months, with improvements persisting at 12 months, with better quality of life, too.
However, other studies found little benefit from taking Saw palmetto, although some of these trials only lasted four weeks which is too short a time to show an effect. Most clinical trials show that Saw palmetto takes around six weeks for benefits to become apparent.
A Cochrane systematic review of 32 randomized, controlled trials (which included those only lasting four weeks) concluded that Serenoa repens did not improve urinary flow measures or prostate size in men with lower urinary tract symptoms consistent with BPH.
Whether or not to try Saw palmetto is a personal decision to make together with your doctor. If you are being managed by ‘watchful waiting’ and are not on any conflicting medications, it remains an option and may help to postpone the need for prescription medicines.
How does Saw palmetto work?
The exact way in which Saw palmetto berry extracts work is unknown although there are several theories. While Saw palmetto does not alter the level of circulating testosterone hormone, it does appear to affect testosterone metabolism in prostate cells.
Saw palmetto and DHT
Enlargement of the prostate gland due to benign prostatic hyperplasia (BPH) is dependent upon the conversion of testosterone to another more powerful hormone, dihydrotestosterone (DHT). This reaction requires an enzyme, 5-alpha-reductase, which is targeted by some drugs prescribed to treat BPH, such as finasteride and dutasteride. Blocking the formatin of DHT reduces prostate size to improve urinary flow rate and obstructive symptoms.
In prostate cell cultures, Saw palmetto extracts block the activity of 5α-reductase by up to 45%. Prostate biopsy samples also show significant reductions in DHT production, and a resulting increase in cell testosterone concentrations, in men who took Saw palmetto extracts for 3 months. These changes were most noticeable in biopsies taken from the middle lobe of the prostate. Selective shrinking of the central portion of the prostate, which directly surrounds the urinary tube (urethra) might explain why studies do not show appreciable shrinking of the whole gland in men taking Saw palmetto, despite significant improvements in urinary outflow and obstructive symptoms.
Interestingly, two different types of 5α-reductase enzyme are present in the human prostate: isoenzymes type 1 and 2, with the type 2 enzyme predominating. The prescription drug, finasteride, mainly inhibits 5α-reductase-2, while Saw palmetto fruit extracts inhibit both. Pharmaceutical drugs are currently in development to inhibit both isoenzymes as this appears to result in a greater, more consistent suppression of DHT in the prostate than selective inhibitors.
Other researchers believe it’s more likely that Saw palmetto extracts compete with DHT for their receptors, however, so that cells detect less DHT even if levels are not greatly reduced.
Saw palmetto and oestrogen
In one study, 35 men with BPH who were due to have prostate surgery were randomised to receive either Saw palmetto berry extracts (160mg three times a day) or inactive placebo in the three months leading up to their op. The number and type of hormone receptors in their prostate cells was then analysed.
In the 17 men who received placebo, oestrogen receptors were found in the nucleus of the prostate cells in 14, and in the main body of the prostate cells in 12. In the men who took Saw palmetto extracts, oestrogen receptors were only detected in the prostate cell nucleus of one out of 18 men, and in the main body of the prostate cells in six men. A significant reduction in progesterone hormone receptors was also noted.
This suggests that Saw palmetto may have a significant anti-oestrogen effect within the prostate gland which is thought to reduce swelling.
One of the most recent cell studies has identified two new prostate proteins with which the beta-sitosterol present in Saw palmetto can interact. One of these (17b-HSD4) is an important ‘housekeeping enzyme’ that inactivates the most powerful oestrogen (17b-estradiol) found in the body. Less is known about the other protein (E-Syt1), but it may be involved in cell proliferation and has been linked to invasiveness in some types of cancer.
Saw palmetto as an alpha-blocker
Some of the most effective prescription drugs prescribed to treat BPH symptoms interact with alpha-adrenergic nerve receptors and are known as alpha-blockers. These trigger relaxation of smooth muscle cells which, in the prostate, reduces spasm and widens the urinary outlet to improve both obstructive and irritative symptoms. Saw palmetto also appears to have alpha-blocker activity which is only slightly lower than that of prescribed alpha-blocker drugs such as tamsulosin, although so far this action has not been fully investigated.
Other actions of Saw palmetto
Saw palmetto appears to affect the movement of calcium ions in and out of the cells to reduce smooth muscle cell contraction. Some of its effects may therefore related to relaxation of smooth muscle cells in the bladder neck and prostate gland. Saw palmetto also has an anti-inflammatory action similar to that of aspirin and ibuprofen, by inhibiting cyclo-oxygenase enzymes which may reduce prostate swelling.
However it works, Saw palmetto is able to reduce the over-proliferation of prostate cells that is associated with BPH to improve symptoms – and this interference with growth of prostate cells even occurs when cells have been stimulated to grow by a powerful growth factor.
Saw palmetto and prostatitis
In prostate cells cultures, Saw palmetto extracts were found to suppress the activity of genes associated with inflammation.
In a study involving 56 men with chronic bacterial prostatitis, all of whom received an antibiotic (prulifloxacin) for 15 days, one group of 28 patients also took Saw palmetto for 8 weeks. The eradication of infection was the same in all men, but those who also received Saw palmetto also had significantly reduced prostate pain and improved urinary symptoms.
Saw palmetto and prostate Cancer
In laboraotry cell cultures, Saw palmetto seed extracts reduced the proliferation of prostate cancer cells. Saw palmetto extracts also appear to activate the programed cell death (apoptosis) of prostate cancer cells. It’s possible that Saw palmeto may offer some protection against prostate cancer, but this is not yet proven.
If you have been diagnosed with prostate cancer, there is currently insufficient evidence to support its use in combination with medical treatments.
Saw palmetto and hair loss
Because Saw palmetto reduces the formation of dihydrotestosterone (DHT) it has been investigated as a treatment for male pattern baldness, which is associated with increased DHT activity within hair follicles.
A hundred men with mild to moderate male pattern baldness took either 320mg Saw palmetto or 1mg finasteride (a prescribed drug) every day for 24 months. Of those taking Saw palmetto, 38% had an increase in hair growth, compared with 68% of those treated with finasteride. So, if you have both lower urinary symptoms due to prostate enlargement and hair loss, you may notice an improvement in both conditions, or you may not – the response is an individual thing based on the genes you have inherited.
Saw palmetto for women
Saw palmetto is sometimes prescribed to women with polycystic ovary syndrome (PCOS). This is because Saw palmetto berry extracts inhibit the formation of dihydrotestosterone (DHT) which is associated with symptoms of this condition, including excess hair growth, oily skin, acne and reduced fertility. Saw palmetto for women is best taken under the supervision of an experienced medical herbalist.
Saw palmetto should not be given to girls. This is a reported case of a 10-year-old girl who developed hot flushes when she was prescribed Saw palmetto berry extracts to treat excessive facial hair (hirsutism). When the Saw palmetto was stopped, so did the hot flashes, and they reappeared when she started taking the herbal medicine again. Around 4 months after starting treatment, the girl had her first period (menarche) at the age of 11. It is possible that puberty was triggered by the Saw palmetto treatment, although this could have been a coincidence of timing.
Saw palmetto dose
The usual dose is 160mg Saw palmetto fruit/berry extract, twice a day, but follow manufacturer’s instructions.
Only Saw palmetto fruit/berry extracts are active against BPH, so avoid supplements that do not specify which part of the tree they contain. Cheaper supplements may contain Saww palmetto leaf extracts, for example, or may only provide low non-therapeutic doses of the active ingredients.
In the UK, some Saw palmetto supplements are licensed under the Traditional Herbal Registration (THR) scheme which will contain a standardised, pharmaceutical grade of Saw palmetto fruit extracts.
Saw palmetto safety
No serious side effects have been reported. Fewer than 1 in 1000 people have reported belchin, stomach discomfort or allergic reactions.
Only take Saw palmetto if your doctor has confirmed that you have benign prostate enlargement, and are being managed with ‘watchful waiting’ to see how your BPH symptoms progress.
If you are taking any prescribed medicines, seek advice from your doctor before taking it, especially before combining it with other prostate medicines, as this should only be done under medical supervision.
Quick Nutrition: Prostate Diet, BPH, Prostatitis, Prostate Cancer is available for Kindle.
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