Having been shown effective as an herbal medicine for testicular conditions, prostate irritation and urination frequency problems for centuries in traditional medicine, numerous studies on Saw palmetto (Serenoa repens or Serenoa serrulata) for prostate conditions illustrated its effectiveness.
But two recent reviews have seemingly stolen away Saw palmetto's shine. This has forced us to ask: Are the reviews credible? And more importantly, is Saw palmetto useful for prostate conditions or not?
In other words, was Saw palmetto's long-lived reputation for easing urinary difficulties and prostate enlargement and its subsequent inclusion into the US Pharmacopoeia and National Formulary in the early 1900s all a big hoax?
The condition on center stage is benign prostatic hyperplasia (BPH). This is a condition whereby the prostate's epithelial cells and stromal cells are significantly increased in men. As their numbers and density increases, the prostate enlarges and puts pressure on the urethra – the canal through which urine flows. This pressure causes urination problems – including greater frequency and a lower flow rate. Pain can also result. Up to three-quarters of men over 75 will have BPH, with most cases starting between the ages of 45 and 50 years old.
Just what is hyperplasia? It is an expansion of cells and tissue typical of inflammatory conditions.
The seemingly game-changing Saw palmetto/BPH review came from the University of Minnesota Medical School and the U.S. Department of Veterans Affairs (Macdonald et al. 2012). The researchers – led by Timothy J. Wilt, MD, a long-time researcher from Veterans Affairs and a professor of medicine at the University of Minnesota Medical School – concluded that Saw palmetto's effects on prostate enlargement were no better than placebo.
Surprisingly, the review only covered three studies. While their initial analysis looked at 17 studies including 2,008 patients, and a previous study by some of the same researchers (including Dr. Wilt) examined 21 studies with 3,139 patients, the researchers eliminated all but three studies, which covered only 661 patients.
The researchers basically eliminated any study that did not use the American Urological Association's Symptom Index or the International Prostate Symptom Scores method to evaluate prostate improvement.
These three studies concluded that Saw palmetto (Serenoa repens) supplements – even when (in one study) doses were increased by two and then three times – were no better than placebo in reducing prostate symptoms.
This negative review is bolstered by another larger Cochrane review led by Dr. Wilt in 2009. This review narrowed 30 studies of 5,222 men down to 18 double-blinded and randomized trials. This review also found that Saw palmetto extracts were no more effective than placebo for improving urinary symptoms, increasing peak urine flow or decreasing prostate size. While Saw palmetto appeared to significantly reduce nighttime urination frequency (nocturia), a "sensitivity analysis" on those results concluded no significant improvements with Saw palmetto treatments.
Yet this finding conflicts with numerous randomized, double-blind studies and previous reviews that have found Saw palmetto reduces prostate symptoms.
For example, a previous Cochrane review, this one also from the most of the same researchers (Wilt et al. 2000), after reviewed 44 studies between 1966 and 1997, selecting 18 double-blinded studies. An analysis of these studies showed that Saw palmetto decreased nocturia by an average of .76 times per night per person (nearly one less urination per night). They also found that men taking Saw palmetto experienced a 72% average improvement of BPH symptoms.
Furthermore, among four studies that compared Saw palmetto with the pharmaceutical Finasteride, Saw palmetto resulted in BPH symptom improvement "comparable to men receiving the finasteride" according to the researchers.
The researchers concluded: "Serenoa repens appears to be a useful option for improving lower urinary tract symptoms and flow measures."
Another study review, again by some of the same researchers (Wilt et al. 2002), reviewed 21 studies involving 3,139 men. Of these, 18 were found to be double-blinded, and of those, seven were eliminated to leave 11 studies with high quality controls and full randomization under Cochrane review criteria.
This review found that Saw palmetto improved urinary symptom scores by about 7.5% over placebo, while reducing nocturia by 24%. Self-reported improvement of symptoms among the Saw palmetto groups averaged 76% higher than placebo groups in these studies.
In two of those studies, Saw palmetto supplementation showed similar improvement in symptom scores as the pharmaceutical Finasteride, but with fewer side effects and 18% fewer people withdrawing from the studies.
The researchers concluded: "The evidence suggests that Serenoa repens provides mild to moderate improvement in urinary symptoms and flow measures. Serenoa repens produced similar improvement in urinary symptoms and flow compared to finasteride and is associated with fewer adverse treatment events."
Note that these two large reviews eliminated many good quality studies that also showed Saw palmetto's effectiveness. Even after their removal there were still plenty of high quality studies that were double-blinded, placebo-controlled and randomized showing Saw palmetto's effectiveness.
For example, researchers from UCLA headed by Dr. Jianyu Rao (2008), randomly assigned 92 men to either receive two capsules of a Saw palmetto extract or a placebo each day for three months. After the treatment period, the researchers found that maximum urinary flow rate increased significantly among those taking the Saw palmetto extract (14 milliliters per second vs. 12). The "relative urinary resistance" was also 20% lower in the Saw palmetto extract group (2.4 compared to 3.0).
The Holes in Pharmaceutical Oriented Research
As we look at the later reviews, we find an increasing number of studies are being eliminated, not because they were not valid studies, or perfectly acceptable to most scientists, but because they did not match the increasingly tighter protocols being applied to pharmaceutical research.
Notably in the case of Saw palmetto, the ability of researchers to utilize subjective feedback from study subjects.
In other words, the full range of individual experiences, which may be slightly different for each person depending upon their health status and lifestyle, is virtually being eliminated by pharmaceutical-oriented research.
This has been proven to be extremely helpful for pharmaceutical researchers, because it enables many individual responses such as "I felt doped up" or "I felt groggy" after taking the pharmaceutical to be virtually eliminated from pharmaceutical research conclusions. These subjective responses are replaced by often uncategorized responses, or those that can be spread out into seemingly unimportant and low-percentile quantifications of negative reactions.
The use of traditional herbs typically comes with just the opposite. People who take traditional herbs can have varying degrees of success with their condition, at the same time experiencing other positive effects such as better sleep, clearer thinking and more energy. These kind of subjective responses, once utilized as a sub-component of herbal research in the past, has become virtually eliminated or constricted down to a statement such as "most patients tolerated the supplement well."
Without some room for subjective responses or some variance in methodology, seemingly positive effects from an herbal supplement can be hammered down to "insignificant" or "no better than placebo" by simply applying strict requirements on what qualifies as improved symptoms. This is how the 2009 Saw palmetto study was able to whittle "significantly improved nocturia" results down to "insignificant" through "sensitivity analysis."
In addition, herbal medicine trials have often come from non-traditional research centers where pharmaceutical-oriented research may not have been the foremost element of focus. A non-traditional research center may apply a different type of symptom index or a more subjective effectiveness score, for example. These studies, despite their being controlled in multiple respects, are often eliminated and labeled "low quality."
Some herbal medicine research has also utilized combination therapies to the single herb being tested. These are also typically eliminated from such reviews.
But there are other reasons we can point to with regard to applying pharmaceutical research constraints onto herbal medicine research, and in particular, the Saw palmetto research.
Herbal medicine therapy typically comes with several important differences from pharmaceutical therapy
- Herbal medicine typically comes with few if any adverse side effects;
- Herbal medicine typically requires longer treatment periods before their benefits take their full effects;
- Patients often respond uniquely to herbal medicine therapy, with varying positive healing effects;
- Herbs contain a variety of constituents and thus different extract forms can contain more or less of the synergy of bioactive substances;
- In most clinical settings, herbal medicine is typically given in combination with other herbal medicines and diet therapies.
The first point – that herbal medicines typically come with few if any negative side effects - has been well established among herbal research for several decades now. This has also been confirmed by comparing epidemiological data between pharmaceutical use and herbal supplement use. The number of illnesses and deaths from herbal supplements are typically in the single digits per year. The 2007 annual report of the American Association of Poison Control Centers reported a grand total of three (yes, 3) deaths from natural remedies during the year. This included herbs, homeopathy, essential oils, minerals, vitamins and other supplements.
In comparison, some studies have reported that over 100,000 Americans die each year from taking correctly prescribed pharmaceuticals. A 1998 report from the University of Toronto estimated that approximately 106,000 people die each year from taking pharmaceuticals (Lazarou et al. 1998). Added to this are deaths from illegal use and overdosing of pharmaceuticals.
This report also calculated that 2,300,000 people will report either ending up hospitalized, permanently disabled, or fatally injured per year as a result of pharmaceutical use in the United States.
A case in point is the pharmaceutical typically used for BPH, Finasteride. Recent research has revealed that Finasteride comes with some serious side effects, including sexual dysfunction, which can continue after treatment is discontinued. These include erectile dysfunction, ejaculation disorder, and impotence (as high as 18% in some research), abnormal ejaculation (as high as 7% in some research), and gynecomastia (large breasts in men) (as high as nearly 3%). Anxiety and depression have also been seen in Finasteride patients.
Yet we find in all the reviews mentioned above that Saw palmetto treatment comes with few if any adverse effects.
Saw palmetto, proven to lower 5α-reductase just as Finasteride does, comes not only with no known adverse side effects: Saw palmetto also produces numerous positive side effects, known clinically among herbalist doctors. These include, believe it or not: increased libido and increased sexual potency.
Wait a second. While Finasteride has been shown in numerous studies to cause sexual impotency while inhibiting 5α-reductase, Saw palmetto also inhibits 5α-reductase while apparently increasing sexual potency? Clinical research has not confirmed its aphrodisiac effects, but traditional use indicates that at least Saw palmetto does not come with the sexual dysfunction side effects of Finasteride.
Let's talk a bit more about 5alpha-reductase, DHT, prostate and Saw palmetto.
DHT and 5alpha-reductase
The link between 5alpha-dihydrotestosterone (DHT), 5alpha-reductase and prostate enlargement is well documented. It is also the basis for the pharmaceutical drug Finasteride. Like Saw palmetto, Finasteride is considered a 5alpha-reductase inhibitor. The two best known drugs containing Finasterid are Propecia – used for baldness – and Proscar – used for prostate hyperplasia. Propecia contains 1 milligram of Finasteride while Proscar contains 5 milligrams.
Herbs such as Saw palmetto have also been shown to naturally lower DHT levels. Saw palmetto inhibits 5α-reductase but it also blocks DHT receptors on cell membranes. A 2002 alopecia study (Prager et al. 2002) of ten balding males found that a combination of Saw palmetto and beta-sitosterol resulted in 60% of the men showing significant hair regrowth.
Researchers from Stockholm, Sweden (Iglesias-Gato et al. 2012) found that Saw palmetto extract inhibited two critical mechanisms involved in prostate cell proliferation: Epidermal growth factor and lipopolysaccharide inducement. Their tests on human androgen-independent epithelial prostate cell lines – shown to proliferate in prostate hyperplasia – illustrated that Saw palmetto extract was productive for inhibiting prostate enlargement on a cellular basis.
The researchers also found that Saw palmetto inhibited monocyte chemotactic protein-1 (MCP-1) secretion related to inflammatory factor IL-12. It also reduced granulocyte-macrophage colony-stimulating factor (GM-CSF). These results showed that Saw palmetto also reduces inflammatory factors related to hyperplasia.
Another laboratory study – this from Barcelona (Pias 2010) – found that Saw palmetto extract significantly reduced 5alpha-dihydrotestosterone (DHT) levels by reducing the enzyme associated with prostate hyperplasia, 5alpha-reductase.