Saw Palmetto per l'ingrossamento della prostata: cosa hanno scoperto realmente gli studi

Ultimo aggiornamento: 25 agosto 2026

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Should I try saw palmetto? It is among the most frequent questions in a prostate clinic, and the reasons behind it are reasonable ones — men who could not tolerate the side effects of prostate medication, and men whose symptoms are mild who would rather start with something they can buy themselves.

The answer has changed since this article was first written, and the title has changed with it. The previous version was headed a good supplement for benign prostatic hyperplasia while its own text said that most studies show it does not work. That contradiction has been resolved in favour of the evidence.

• Centro di urologia ospedale di Bangkok Thailandia Prenotazione online 02-310-3009 bhquro@bdms.co.th
• Ospedale Samitivej Sriracha Chonburi 088-022-1445

What saw palmetto is

Saw palmetto (Serenoa repens) is an American dwarf palm. An extract of its berries, containing fatty acids and phytosterols, has been sold for prostate symptoms for decades and is proposed to act through anti-androgenic, anti-inflammatory and pro-apoptotic effects on prostate tissue. Those mechanisms are plausible in the laboratory. The question is whether they translate into a man passing urine better, and that is answered by trials rather than by mechanism.

What the two largest trials found

This has been tested properly, twice, in large randomised placebo-controlled trials in the United States.

• Il STEP trial gave men a standardised saw palmetto extract for a year and found no difference from placebo in urinary symptom scores or urine flow.
• Il CAMUS trial then tested the obvious objection — that the dose had been too low — by escalating up to three times the usual daily amount over eighteen months, using a well-characterised extract. It found no benefit over placebo at any dose.

A correction to the explanation given here previously

The earlier version of this article accepted that the trials were negative, but attributed that to poor product quality — extracts varying between manufacturers, active ingredients lost in processing — and concluded that the right preparation at the right daily amount, with a fatty acid content above a stated percentage, would work. That reasoning does not survive the CAMUS result, which used a characterised extract at escalating doses and still found nothing. The specific daily amount and the fatty acid specification have therefore been removed from this article: publishing them steered readers towards buying a particular grade of an unregulated product on the strength of an argument the evidence does not support.

Product variability between brands is real. It is simply not the reason the trials were negative.

The real risk is not the supplement itself

Saw palmetto is generally well tolerated. Mild digestive upset is the usual complaint, and bleeding has been reported often enough that it is worth mentioning to your doctor if you take an anticoagulant or antiplatelet drug, or before any surgery.

The greater risk is what happens while a man is taking it. The symptoms attributed to an enlarged prostate — a weak stream, getting up at night, urgency, incomplete emptying — are not exclusive to benign enlargement. Prostate cancer, bladder cancer, bladder stones, a urethral stricture, diabetes and neurological disease all present the same way. A man who buys a supplement, feels no worse, and does not attend for two years has not treated his prostate; he has postponed finding out what the problem is.

There is a related practical point about blood tests. Prescription 5-alpha reductase inhibitors roughly halve the PSA reading, and anyone interpreting a PSA must know the patient is taking one. Reported effects of saw palmetto on PSA have been inconsistent, but the principle is the same: tell whoever orders your PSA about every prostate supplement you take, so the number is read correctly. See Devo fare un test PSA.

What does work, if the symptoms are bothering you

• Nothing at all, for genuinely mild symptoms. Watchful waiting with simple measures — timing of fluids, reducing evening alcohol and caffeine, reviewing diuretics and antihistamines — is a legitimate and evidence-based choice, and it is the honest alternative to a supplement for men who want to avoid medication.
• Alfa-bloccanti work within days. The commonest reasons for stopping them are dizziness on standing and a change in ejaculation, both reversible.
• 5-alpha reductase inhibitors shrink a large prostate over months and reduce the risk of retention and surgery, at the cost of possible sexual side effects.
• Procedure where medication fails or is not wanted, including terapia con vapore acqueo and prostate resection, both available at Bangkok Hospital Headquarters.

If, knowing all of the above, you still wish to try saw palmetto, that is a defensible choice for mild symptoms — it is inexpensive and unlikely to harm you. It should be a decision made with the information in front of you rather than on the strength of a search result, it should not replace assessment, and it should not be continued indefinitely if nothing changes.

Symptoms that need attention rather than a supplement

Get medical attention for any of the following. In an emergency in Thailand, call 1669.

• Incapacità completa di urinare with a painful full bladder — this is acute retention and needs same-day treatment.
• Sangue visibile nelle urine, con o senza coaguli.
• Fever with pain low in the abdomen or on passing urine.
• Symptoms that came on suddenly rather than gradually over years.
• New bone pain, unexplained weight loss, or leaking urine continuously without warning.

Frequently Asked Questions About Saw Palmetto for BPH

Does saw palmetto actually work for an enlarged prostate?

The two largest randomised placebo-controlled trials found no benefit over placebo in urinary symptoms or flow rate — including one that tested up to three times the usual daily amount using a characterised extract. On the best available evidence, it does not meaningfully improve BPH symptoms.

What dose should I take, and which brand is best?

This article previously gave a specific daily amount and a fatty acid specification for choosing a brand. Both have been removed. The argument behind them — that the trials failed because the extracts were inadequate — does not hold, since a dose-escalation trial with a characterised extract also found nothing.

Is it harmful?

Not usually. Mild digestive upset is the commonest complaint, and it is worth telling your doctor you take it if you are on blood-thinning medication or about to have surgery. The greater risk is delay — treating prostate symptoms without establishing what is causing them.

Will it affect my PSA test?

Reported effects have been inconsistent, unlike prescription 5-alpha reductase inhibitors, which roughly halve the reading. Either way, tell whoever orders and interprets your PSA about any prostate supplement you take.

I cannot tolerate prostate medication. What are my options?

Side effects differ between drugs and between individuals, so a different agent within the same class is often worth trying before abandoning medication altogether. For mild symptoms, watchful waiting with fluid timing and a review of other medicines is a legitimate plan. Where medication is unsuitable or unwanted, procedural options including water vapour therapy exist and are discussed at consultation.

Come fissare una visita

If prostate symptoms are affecting your sleep or daily life, Dr. Soarawee Weerasopone sees patients at Bangkok Hospital Headquarters e presso il Samitivej Sriracha Hospital di Chonburi il 088-022-1445. Bring a list of every supplement and medicine you take, including the ones bought without a prescription.

La telemedicina del Bangkok Hospital è disponibile per i pazienti che non possono presentarsi di persona, compresi i pazienti internazionali: va organizzata in anticipo via email con il reparto di urologia all'indirizzo bhquro@bdms.co.th. Samitivej Sriracha è solo in presenza. Le richieste sui costi ricevono risposta dall'ospedale, non da questo sito web.

Avvertenza: Questo contenuto è scritto e rivisto dal Dr. Soarawee Weerasopone, urologo certificato presso il Bangkok Hospital Headquarters (BHQ), ed è destinato esclusivamente a scopo educativo. Non costituisce un parere medico, una diagnosi o una prescrizione per alcun singolo individuo, e non vengono forniti pareri, diagnosi o prescrizioni tramite canali di messaggistica privata o social media. Il Dr. Soarawee non gestisce alcun account pubblico sui social media; qualsiasi account che offra consulenze private a suo nome è fraudolento. In caso di emergenza in Thailandia, chiamare 1669.