Saw Palmetto: Benefits, Side Effects, and Dosages

Saw palmetto is a herbal remedy used to treat testosterone-related health issues. Some of these include male-pattern hair loss, low libido, and hormone imbalances.

But the most well-known of saw palmetto’s benefits is for benign prostatic hyperplasia, or an enlarged prostate. It may help stop the growth of the prostate gland or cause it to shrink.

Science, however, has produced conflicting reports about these claims.

In this article, we will examine the prospective benefits of saw palmetto for prostate health as well as its potential to treat a variety of ailments.

What Is Saw Palmetto?

Saw palmetto (Serenoa repens) is a small palm tree native to the southeastern U.S. and the Caribbean. It belongs to the Arecaceae family of plants, characterized by large, fan-like leaves and branchless stems or trunks.

For its part, the saw palmetto is virtually trunkless. The hardy shrub creeps low to the ground in clumps, covering the floors of pine forests and sandy coastlines in the Gulf region and south Atlantic.

Sharp, spiny teeth lining the leaf stalks give saw palmetto its name. And the sizeable oblong fruits it yields are the source of its medicinal properties.

The fleshy berries have a long history in traditional American medicine. Since the 1700s, Native Americans in the region have used them to treat urinary and reproductive issues in men.

The Indigenous people and early American settlers also observed positive effects in animals who ate the fruit. They, in turn, consumed the berries for benefits such as:

• Gaining weight
• Improving breastmilk supply
• Promoting calm
• Expelling mucus
• Relieving coughs

Fast forward to the 20th century through today, and scientists have begun to identify the potential bioactivity behind these observations: fatty acids and plant sterols.

Saw Palmetto: Benefits and Uses

Whole, ripe saw palmetto berries contain beneficial fats and antioxidant phytosterols that may contribute to numerous health benefits.

However, for medicinal and research purposes, you’re more likely to find saw palmetto in extract form. Extracts provide a higher concentration of bioactive ingredients.

Researchers have mainly directed their studies towards the effect of saw palmetto extracts on testosterone levels. By modifying testosterone, they may positively impact conditions like enlarged prostate, male-pattern baldness, and more.

Benign Prostatic Hyperplasia (BPH)

Saw palmetto is widely used to treat benign prostatic hyperplasia (BPH). This is a noncancerous enlargement of the prostate—a walnut-sized gland that surrounds the urethra and produces semen fluid.

A man’s prostate naturally grows in size with age. In fact, according to the American Urological Association, over half of all men will have BPH by age 60. But when the prostate grows very large, it can press on the urethra (a tube that carries urine from the bladder out of the body) and cause issues like:

• Trouble starting a urine stream
• Weak urine flow
• Frequent urination (including overnight)
• Painful urination
• Accidental leakage of urine

Collectively, these signs are known as lower urinary tract symptoms (LUTS).

While doctors aren’t entirely sure why the prostate increases in size, they suspect it could have something to do with the changing testosterone levels in older men.

That’s where saw palmetto extract may help. Studies indicate the extract may block the action of 5-alpha reductase, an enzyme that converts testosterone into dihydrotestosterone (DHT). DHT is thought to contribute to prostate enlargement.

What Studies Say

Research suggests the fatty acids in saw palmetto extracts are to thank for their enzyme-blocking ability. With less circulating DHT, the prostate may grow smaller. This could relieve symptoms.

Data collected from several studies suggest saw palmetto extracts can improve LUTS in patients with BPH.

For example, a double-blind, placebo-controlled study, published in the British Journal of Clinical Pharmacology in 1984, found that a saw palmetto berry extract called “Permixon” significantly improved BPH symptoms.

For the 30-day study, 110 patients with symptoms of painful urination, excessive nighttime urination, and poor urine flow were assigned to two groups—one receiving 320 milligrams (mg) of Permixon daily and the other a placebo.

A six-month observational study published in 1998 similarly concluded that saw palmetto is a “well-tolerated agent” that may significantly improve LUTS in men with BPH.

Meanwhile, a 2015 randomized controlled study found that a combination of saw palmetto and the bladder muscle relaxant tamsulosin was more effective than tamsulosin alone in reducing storage symptoms in BPH patients six months and up to 12 months post-treatment.

Yet, in a systematic review of 32 studies and 5,666 men, published in the Cochrane Database of Systematic Reviews in 2012, researchers concluded that saw palmetto extract worked no better than a placebo—even at high doses.

So, results have been mixed. Larger, higher-quality studies are required before saw palmetto can be strongly recommended to manage BPH.

Prostate Cancer

Naturally, many wonder if saw palmetto’s potential benefits for enlarged prostate extend to prostate cancer. Prostate cancer is characterized by the uncontrolled, malignant growth of cells in the prostate gland.

In lab studies, saw palmetto has shown anti-androgen and anti-inflammatory activity.

Androgens are the hormones responsible for male sex characteristics. They include testosterone and its byproduct, DHT.

A 2007 study found that the extract slowed the growth of androgen-dependent prostate cancer cells while also inducing apoptosis (cell death). Specifically, researchers said that saw palmetto downregulated expression of prostate-specific antigen (PSA) triggered by DHT.

PSA is a protein made by the prostate gland, and unusually high levels may indicate the presence of cancerous cells.

In a 2013 study of human carcinoma prostate cells, Permixon was shown to stop cell growth. Scientists believed this effect was due, in part, to the suppression of inflammatory genes. They also credited it to the activation of the nuclear factor-kappa B (NF-κB) pathway in prostate tissue.

NF-κB helps regulate the immune system’s response to infection. Its dysfunction is associated with inflammatory diseases as well as cancer.

The antioxidants epicatechin and methyl gallate in saw palmetto may contribute to the anti-inflammatory action.

While these results are promising, they aren’t conclusive. Other studies have shown no link between saw palmetto use and reduced cancer risk.

As such, it is not considered an effective treatment for prostate cancer.

Male-Pattern Hair Loss

The androgen hormone DHT is also linked to male-pattern hair loss. Long-term exposure to DHT, which happens with age, seems to shrink the hair follicles. This causes hair to grow in thinner, weaker, and more slowly. Eventually, new hair growth stops altogether.

Saw palmetto’s ability to block the enzyme that turns testosterone to DHT could prevent hair loss.

One lab study found that a saw palmetto extract worked nearly as well as the hair-loss drug finasteride in blocking 5-alpha reductase.

Other research shows that topical application of saw palmetto may reduce androgenetic alopecia (AGA), as this hair-loss type is formally known. In one study of 25 men with AGA who used a saw palmetto lotion for four months, patients’ total hair count increased by 11.9%.

What’s more, the final ratio of anagen (active growth phase) hair to telogen (resting phase) hair was up 38%, compared to the pre-treatment period.

This area of research is very limited, however. More robust trials will determine if saw palmetto is a viable treatment for hair loss.

Other Benefits and Uses

Evidence of saw palmetto benefits for other health issues is mostly anecdotal. But while the supporting research is lacking, there are some interesting theories.

• Weight gain: Saw palmetto berries are rich in medium-chain fatty acids and carbohydrates. These nutrients can certainly contribute to weight gain when consumed in large amounts.
• Increased milk production: Women with a low milk supply due to polycystic ovary syndrome (PCOS) sometimes use saw palmetto. PCOS is a condition where a woman produces excess androgen hormones. The thought is that the herb’s hormone-modulating properties can bring hormone levels back into balance, thereby increasing breastmilk production. However, these same hormone effects could be harmful to infants, so most experts advise against saw palmetto use when nursing.
• Calming benefits: A few studies have suggested that saw palmetto extract may relax the smooth muscles of the lower urinary tract. Muscle relaxers are known to have sedative (calming) effects, depressing the central nervous system. This may contribute to the herb’s soothing effects.

Saw Palmetto Side Effects and Precautions

Saw palmetto is generally considered safe for most people. Reported side effects have been mild and include:

• Cramps
• Dizziness
• Headaches
• Nausea
• Vomiting
• Diarrhea
• Constipation

That said, few studies focus directly on the supplement’s safety, especially in women. Its potential long-term effect on developing fetuses and young children is also understudied.

Due to this and saw palmetto’s effect on hormones, pregnant and breastfeeding women, children, and adolescents should not take the herb.

In the same vein, people with sex-hormone-sensitive cancers should discuss its use with their doctor.

Allergies are a concern with any herbal treatment. Discontinue use and contact your doctor if you experience symptoms such as sneezing; itchy, red eyes; hives; swelling of the lips, tongue, or throat; or shortness of breath.

There have also been case reports of acute pancreatitis, liver damage, and hot flashes followed by menarche in preadolescent girls.

Furthermore, saw palmetto has shown anti-blood-clotting effects in studies. Experts recommend not taking saw palmetto at least two weeks before surgery.

Saw Palmetto Dosages

Saw palmetto berry is available in capsule, tablet, dried powder extract, or tincture form. You can also buy the whole fruit dried for use in teas.

The oily lipid extract is the most popular and well-studied form. In studies, dosages of 320 mg per day seem to be most effective for enlarged prostate symptoms.

As with all medications, it’s important to follow the instructions on the label. You should also seek guidance from your healthcare provider, as they will take your medical history and possible drug interactions into consideration.

Below are a few interactions to look out for:

• Contraceptive drugs: Saw palmetto appears to reduce the effects of estrogen in the body. Since some contraceptives (pills, patches, vaginal rings) contain estrogen, saw palmetto may decrease their effectiveness.
• Anti-blood clotting medications: Combining saw palmetto with anticoagulants/antiplatelets could be dangerous, as the herb is known to slow blood clotting. The result could be heavy bleeding or bruising.
• Estrogen pills: Saw palmetto’s potential estrogen-blocking properties may reduce the effectiveness of estrogen replacement pills.

Final Thoughts on Saw Palmetto

Saw palmetto shows great promise in managing BPH symptoms, blocking prostate cancer cell growth, and treating androgenetic hair loss. But there have been inconsistencies in results between studies.

More research is needed to determine whether the herb can safely and effectively treat these health issues and more.

If you’re interested in trying saw palmetto to improve your health, talk to your doctor first. Your doctor will help you decide if the potential benefits outweigh the risks.