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Erectiestoornissen / Erectile dysfunction

Herbs and Erectile Dysfunction: A Review of Traditional Use and Modern Clinical Evidence 
by Linda Woolven, Ted Snider 
HerbalGram. 2013; American Botanical Council

Since ancient times, cultures around the world have turned to herbs for help with erectile dysfunction (ED). The astonishing number of plants that have been believed to possess aphrodisiac and performance-enhancing powers suggests that people in every geographical location and throughout every era have sought herbal help for fertility and reproductive power. Ethnobotanist James A. Duke’s database of herbs lists 239 herbs that reportedly have been used as folkloric aphrodisiacs and 122 that have been used for impotence (J. Duke, email, July 2, 2013). There is an ancient and intimate relationship between man and nature in the quest for enhanced sexual power.
Although some of the folkloric solutions seem truly outrageous, others have been vindicated by science. While doing field work in Tobago, the authors of this article came across a popular beverage tellingly titled “Hard Wine,” which combined the equally aptly named horny goat weed (Epimedium sagittatum, Berberidaceae) with eleuthero (Eleutherococcus senticosus, Araliaceae) and a tree bark called bois bandé — all soaked in a red fruit wine.

The label and the hyped claims lent the product an air of illegitimacy. But horny goat weed does have a tradition of increasing virility and fertility. Known in China as yin yang huo, which translates literally as horny goat weed, the herb has been used for more than a thousand years for sexual conditions, including those of impotence and fertility.1 In Traditional Chinese Medicine (TCM), horny goat weed is used to increase sexual energy in both men and women through its ability to “warm the kidneys.” In TCM, low energy of the kidney is often involved in sexual problems. Some studies support horny goat weed’s long history of traditional use. One study found that people on dialysis for kidney failure had improved sex drives when given horny goat weed, compared to people who did not get the herb.2 Other studies have found that horny goat weed can restore low levels of testosterone.3
The most mysterious herb in Hard Wine, and the one that generated the most discussion on the streets of Tobago, is bois bandé (Richeria grandis, Phyllanthaceae). Though virtually no reliable scientific information on this herb has been found, the authors did locate one published interview with healers from Trinidad and Tobago in which bois bandé came up as a treatment for ED.4

Likewise, Dr. Duke encountered an herbal formula with a name to rival Hard Wine. Rompe calzon is a Latin American aphrodisiac that, like Hard Wine, is soaked in wine or rum.Rompe calzon means “bust your britches.” There are only anecdotes for this herbal formula, however, as no studies exist. But it is intriguing that both rompe calzon and another Latin American formula Dr. Duke encountered called siete raices (“seven roots”) contain the Peruvian herb clavohuasca (Tynanthus panurensis, Bignoniaceae). Could there be something to these formulae as there has been for horny goat weed?

The biggest problem facing herbal formulae for erectile dysfunction today, though, is not incredibility. Science actually has vindicated a number of the traditional herbs. Instead, the most common concern is deception and adulteration. Ignoring or distrusting the science that suggests certain herbs really work and wanting to exploit lucrative opportunities, some marketers are adulterating products — which claim on the label to be natural — with unlabeled pharmaceutical ingredients. As some responsible parties in the industry prefer to phrase this situation, unscrupulous sellers are illegally marketing conventional pharmaceutical drugs masquerading as herbal dietary supplements.
The problem started occurring with increasing frequency a few years ago. In 2004, researchers found that approximately half of 40 botanical ED products analyzed contained the active ingredients of Viagra® (sildenafil), Cialis® (tadalafil), or Levitra® (vardenafil).5 In another study a year later, two out of seven natural ED products tested contained either sildenafil or tadalafil.6 Again, in 2006, sildenafil analogues (compounds with similar chemical structures) were found in herbal products marketed for ED.7

Though probably a more common concern when buying “herbal” ED products online than when buying them in a retail store, the problem is both serious and ongoing. In 2011, Health Canada warned, “An increasing problem with ‘herbal’ or ‘natural’ unauthorized products promoted for erectile dysfunction is that they contain analogues of erectile dysfunction drugs.”8A year later, Health Canada issued a warning to consumers not to buy four herbal products promoted for ED because they were found to contain either prescription or unlicensed medicines. In 2011, the US Department of Agriculture issued a warning that an analysis had identified a sildenafil analogue in an herbal ED product. And in 2012, the US Food and Drug Administration (FDA) cautioned consumers on buying dietary supplements for ED online. An FDA Internet survey found that six of 17 products contained sildenafil or substances similar to it, and then listed 29 products to avoid.9 The Medicines and Healthcare Products Regulatory Agency in the United Kingdom said in 2013 that it was “advising consumers not to buy ‘herbal’ remedies sold as a treatment for erectile dysfunction” because “evidence from around the world suggests that such products are often adulterated with random quantities of pharmaceutical substances.”10

Herbs Showing Efficacy for ED
Erectile dysfunction is the inability to attain or maintain an erection sufficient for satisfactory sexual function. Fifty-two percent of men between the ages of 40 and 70 are affected by ED.11 The prevalence of ED is expected to increase over the next several years until it affects 322 million men worldwide by the year 2025.12
There are several possible causes for ED. These include depression, stress, anxiety, fatigue, diabetes, hypothyroidism, prostate disorders, low testosterone, high estrogen, atherosclerosis, cigarette smoking, and excessive alcohol consumption.13 In fact, some research suggests that in 20% of ED cases the cause is psychological.14 Several pharmaceutical drugs also can cause ED; blood pressure-lowering drugs are the most problematic,15 but antidepressants,16,17 the ulcer medication cimetidine,18 and the benign prostatic hyperplasia drugs finasteride19,20 and tamsulosin (Flomax®)21 are also common culprits.
Not all botanical manufacturers of ED products are unscrupulous. The market also contains legitimate herbal products that have had their botanical identity and raw materials authenticated, and many have at least one or two well-controlled clinical trials, or substantial history of traditional use, supporting the ED claim. That these legitimate products should be cast under a negative shadow and that people who could benefit from taking them are warned away is unfortunate because ED is a serious and increasingly common problem, the pharmaceutical solutions are not without side effects, and legitimate herbal products do offer viable options for treatment.

Ginkgo Extract
A very promising herb for treating ED is the standardized extract of ginkgo (Ginkgo biloba, Ginkgoaceae) leaf. One of the most valuable and versatile of all herbs, ginkgo is well known for its ability to increase circulation to the extremities, including the head, hands, and feet. So it is not entirely surprising that a condition often caused by lack of blood flow to the penis could also be helped by ginkgo extract.

At least two studies show the promise of ginkgo for reducing symptoms associated with ED. One study included 60 men suffering from ED caused by impaired penile arterial blood flow. For 12 to 18 months, men consumed a low dose of 60 mg per day of ginkgo extract (EGb 761®, W. Schwabe, Karlsruhe, Germany*; 50:1; 6% terpenes, 24% ginkgo flavonol glycosides). What is especially interesting about the study is that all of the men had failed to respond to injections of papaverine, a conventional pharmaceutical drug composed of the alkaloid derived from opium poppy (Papaver somniferum, Papaveraceae) that is used to improve blood flow in people with circulatory problems. It works by relaxing blood vessels and is employed for ED. However, its use had not benefited any of the men in this study, suggesting that they were difficult-to-treat cases. But after only six-to-eight weeks on ginkgo, improvement in penile arterial flow was evident. And after six months, 50% of the subjects had resolved their ED. In another 20% of the study participants, a subsequent attempt at papaverine ED treatment was then successful.22

The second study was double-blinded and administered the more common higher dose of 240 mg ginkgo extract (EGb 761). In this nine-month study, 50 men with arterial ED were divided into two groups: those who had experienced some previous success with medication, and those who had not. All of the men who had experienced some response to conventional drugs regained spontaneous erections after six months on ginkgo. All of them had objective improvement in erectile function, including improved rigidity at both the tip and the base of the penis, as well as improvements in arterial flow rate. Perhaps even more impressively, of the 30 men who had experienced no success with medications, 19 of them responded to the ginkgo. All study participants showed improved objective response parameters.23
Ginkgo extract likely works by improving blood flow to the erectile tissue by enhancing arterial and vascular blood flow. Ginkgo relaxes the corpus cavernosum vascular smooth muscles. The corpora cavernosa are the cylindrical blood sinuses that form the erectile tissue of the penis and expand when filled with blood. Ginkgo’s effect on the corpus cavernosum is thought to be a mechanism of action that contributes to improvement in ED. Ginkgo extract also has vasodilating action.

Asian Ginseng Root
The herb that is generating perhaps the most scientific support for ED is Asian ginseng (Panax ginseng, Araliaceae), which has been employed for sexual dysfunction in traditional Asian medicine for centuries. The first important study of ginseng and ED was published in 1995. This trial gave either 1,800 mg of Korean red ginseng extract (extract description not given), a pharmaceutical drug (trazodone), or a placebo to a total of 90 men with ED, with 30 men in each group.24 Red ginseng is the same root as white ginseng, but, whereas white ginseng is simply the dried mature root, red ginseng is the fresh root that has been steamed for two-to-three hours before it is dried. The steaming leads to a change in the profile of the major ginsenosides, and thus a change in the root’s (and the extract’s) pharmacology.25 Red ginseng is held to be “warmer” and “more stimulating,” according to the energetics principles of Asian traditional medicine. In the aforementioned trial, the ginseng increased erectile function in significantly more men: 60% in the ginseng group versus only 30% in the placebo and trazodone groups (P<0.05). Ginseng brought about significant improvement in the rigidity and width of the erection, as well as in the ability to maintain an erection and in patient satisfaction (P<0.05). As a bonus, it also significantly improved libido. Though there were no complete remissions in this study, the partial improvements were significant.

Further, in a double-blind, placebo-controlled study, a total of 45 men with ED were given either 900 mg of powdered Korean red ginseng or a placebo three times a day for eight weeks. Sixty percent of the men on the ginseng had improved erections, according to the global efficacy questionnaire. Erection scores increased by 41.7% in the ginseng group compared to only 6% in the placebo group. The total five-part International Index of Erectile Function (IIEF) scores were significantly higher in the ginseng group than in the placebo group, with an improvement of 36.2% versus 10.4% (P<0.01). Penile rigidity was significantly better in the ginseng group. Penetration and maintenance of erection were significantly higher in the ginseng group than in the placebo group (P<0.01). And, again, ginseng improved sexual desire.26
Another double-blind, placebo-controlled study gave either 1,000 mg of Korean red ginseng (presumably dried powdered root) or a placebo three times per day to 60 men with mild-to-moderate ED. After 12 weeks, IIEF scores had improved from 16.4+/-2.9 to 21.0+/-6.3 (P<0.0001). In the ginseng group 66.6% of the men had improved erections; there was no significant effect in the placebo group. The ginseng was significantly better for rigidity, penetration, and maintenance (P<0.01) as well.27

In the first-ever systematic review of clinical research on Korean red ginseng and ED, researchers found seven randomized, controlled clinical studies that included a total of 363 men. In the six studies that compared ginseng to a placebo, the ginseng improved erectile function more than the placebo in each individual trial. Combining the studies into a meta-analysis, the researchers found that this was not due to a placebo effect, as the ginseng had a significant effect (P<0.00001). Ginseng is not only effective, but safe; adverse events were scarce and mild. Interestingly, the meta-analysis found that the red ginseng also produced significant improvement when the ED was from psychological causes (P<0.001).28
Recent studies have postulated that Asian red ginseng may help ED by directly inducing relaxation of the smooth muscles of the corpus cavernosum via nitric oxide pathways.27,29Ginseng’s mechanism of action against ED is not yet fully understood.

Muira Puama
Another potentially valuable herb for ED is muira puama (Ptychopetalum olacoides, Olacaceae). This potential application is no surprise in Brazil, where the herb is known as “potency wood,” and has been used for many years. Muira puama seems to address both the physical and psychological problems associated with impotency. A study done by Jacques Waynberg, MD, PhD, of the Institute of Sexology in Paris, found that of 262 men suffering from ED or lack of sexual desire, 62% of those with loss of desire were helped by 1-to-1.5 grams of muira puama extract (not described in the study), and 51% of those with ED benefited from the herb.30 Muira puama’s efficacy for ED seems to be due in part to its nerve-stimulating properties. The mechanism of action of its aphrodisiac effect on sexual desire remains unknown.

Multi-Herb Combination
A recent double-blind, placebo-controlled study combined muira puama, Asian ginseng, and ginkgo with horny goat weed and five additional herbs.31 The nature of these preparations was not specified or described in the trial. Seventy-eight otherwise healthy men with mild-to-moderate ED, scoring 11-23 on the Erectile Function domain of the IIEF, were given a placebo or a proprietary herbal product known as VigRx Plus® (Leading Edge Herbals; Greeley, CO). The capsules contain 100 mg Asian ginseng, 100 mg ginkgo extract, 100 mg hawthorn (Crataegus monogyna, C. laevigata, Rosaceae) berry, 50 mg muira puama, 50 mg catuaba (Erythroxylum catuaba, Erythroxylaceae), 25 mg Chinese dodder (Cuscuta chinensis, Convolvulaceae) seed, 15 mg horny goat weed, 75 mg tribulus (Tribulus terrestris, Zygophyllaceae), 100 mg damiana (Turnera diffusa, Turneraceae), and 5 mg BioPerine® (a proprietary standardized extract of piperine from the fruit of black pepper [Piper nigrum, Piperaceae]; Sabinsa Corporation, East Windsor, New Jersey). The capsules were administered at a dose of two capsules twice per day, and the study lasted 12 weeks.

The men given the herbal combination had a statistically significant increase in erectile function compared to the placebo group (P<0.0001). Scores on the Erectile Function domain of the IIEF increased by nine points (16.08 to 25.08) in the herb group compared to an increase of only 0.61 points (15.86 to 16.47) in the placebo group. Thirty-four percent of the herb group, compared to only 3% of the placebo group, attained erections that were always or almost always hard enough to achieve penetration. Equally importantly, as ED is the inability to attain or maintain an erection, the ability to penetrate and to maintain an erection after penetration improved by 59% and 63%, respectively, in the herb group, but by only 4% and 9% in the placebo group. Fourteen out of 39 men had scores greater than 25 by the end of the study, indicating no presence of ED, compared to only one of 36 in the placebo group. The men in the herb group also experienced significant improvement compared to placebo in all other categories of the IIEF, including sexual desire, orgasmic function, intercourse satisfaction, and overall satisfaction. The mean increase in the total IIEF score was 20.1 in the herb group compared to only 1.0 in the placebo group. The herbal treatment was rated as good or excellent by 95% of men, while the placebo was rated as poor by 67%.

On the Erectile Dysfunction Inventory of Treatment Satisfaction scale, the mean treatment satisfaction score was 82.31 in the herb group versus 36.78 in the placebo group. The difference in satisfaction was even greater for their partners: 82.75 in the herb group versus only 18.50 in the placebo group. Ninety percent of the men on the herbs wished to continue treatment compared to only 3% of the placebo group. The herbs were not only apparently effective but presumably safe; adverse effects were minor and similar in both groups.

Among the other herbs in the formula, though no clinical studies exist, the herb damiana has been prized as an aphrodisiac by Mexican cultures since antiquity. Damiana is thought to work by slightly irritating the urethra, which increases the sensitivity of the penis.15 Hawthorn, especially the leaf and flower extract, exerts a blood pressure-lowering effect by dilating coronary vessels, acting as an ACE (angiotensin-converting enzyme) inhibitor and diuretic, and increasing heart function.32 Chinese dodder is used in TCM for impotence. Catuaba is a Brazilian herb that is a non-cocaine-containing relative of the coca plant (E. coca) used in the Amazon region as an aphrodisiac. Saw palmetto (Serenoa repens, Arecaceae) berry 9-12:1 ethanol extract (Prostasan®; A. Vogel Bioforce AG; Roggwil, Switzerland) has been shown in a pilot trial to improve sexual function by more than 30 percent in men whose ED is caused by benign prostatic hyperplasia.33

Tribulus terrestris has been used in Ayurvedic medicine and in European folk medicine as an aphrodisiac and for the treatment of impotence. Several studies exist to support this traditional use.34-36 However, most of this research is non-blinded and of questionable quality. Much of it is research on animals that often has failed to be duplicated in human studies. For the most part, the published research is poorly designed with results that are not definitive. There is little in the way of well-controlled trials, making conclusions on tribulus difficult.37,38

One recent double-blind study, however, is potentially promising because the comparison group received the drug Cialis (tadalafil).39 The subjects in this study were 70 men over the age of 60 with reduced libido and with or without ED. They were given either Cialis or a supplement called Tradamixina® (Tradapharma, Lugano, Switzerland), consisting of 396 mg of tribulus (form not specified) combined with 150 mg of the brown algae arame (Ecklonia bicyclis, Lessoniaceae) and 144 mg of glucosamine (identified as D-glucosamine and N-Acetyl-D-glucosamine) twice per day for two months. Testosterone levels increased significantly in the tribulus combination group and non-significantly in the Cialis group. Nocturnal erections improved in the tribulus combination group, and total IIEF scores improved in the tribulus combination group but only non-significantly in the Cialis group. The specific erectile function area of the IIEF improved in both groups, but it improved more in the Cialis group; the Sexual Quality of Life score improved in both groups, but more so in the tribulus group. Libido improved in the tribulus group but not in the Cialis group. The authors concluded that Tradamixina is effective for mild-to-moderate ED in men with low testosterone and that it is free from the adverse side effects of Cialis.

A potential limitation of this study that somewhat interferes with drawing conclusions about tribulus is that it was combined with other supplements. Because some of the men in the study had ED and some did not, it would be interesting to determine if the tribulus improved symptoms in the specific subgroup of men with ED or whether the improvement was attributable to the observed improvement in libido.
The primary active constituent in tribulus is believed to be protodioscin. Protodioscin is a steroidal saponin that is thought to convert to DHEA (dehydroepiandrosterone) and to increase testosterone, dihydrotestosterone, and luteinizing hormone.40,41 Protodioscin may also contribute to the relaxation of the corpus cavernosum.42 Many of these actions of tribulus await confirmation in human studies.

Maca, Pycnogenol®, Rhodiola rosea, Eurycoma, Ashwagandha, Oats, and Yohimbe
Maca. Another South American herb that may help with ED is maca (Lepidium meyenii, Brassicaceae), an edible tuber that grows at high altitudes in the Peruvian Andes. In a double-blind study, 50 young men with mild ED were given either 1,200 mg of pulverized and dehydrated maca root or a placebo twice a day for 12 weeks.†43 IIEF scores improved significantly in both groups, but they improved significantly more in the maca group than in the placebo group (1.6+/-1.1 versus 0.5+/-0.6; P<0.001). Subjectively, though scores on the Satisfaction Profile (SAT-5) improved significantly in both groups, once again, the SAT-5 scores improved significantly more in the maca group (9+/-6 versus 6+/-5 in the placebo group; P<0.05). Further, only the maca produced significant improvement in the physical and social performance-related SAT-5 scores. Maca also has been shown to improve libido in healthy men.44,45

Pycnogenol®. A botanical preparation that takes a promising approach to ED is the patented extract from French maritime pine bark (Pinus pinaster, Pinaceae), known commercially as Pycnogenol® (Horphag Research; Geneva, Switzerland). For an erection to occur, the blood vessels to the penis must dilate. Such dilation depends on nitric oxide (NO), which triggers the relaxation of the cavernous smooth muscle. Pycnogenol has been shown to enhance the production of NO.46,47 When researchers gave either 120 mg of Pycnogenol per day or a placebo to 21 men diagnosed with ED in a double-blind study, after three months, ED symptoms were significantly improved in the Pycnogenol group (P<0.05). The placebo had no effect. According to the IIEF-5 scoring, Pycnogenol decreased ED severity from moderate to mild.48

Nitric oxide is dependent on the amino acid arginine, which may hold promise for helping ameliorate ED.49 In a double-blind, placebo-controlled study, 50 men with ED were given either 5 g per day of L-arginine or a placebo for six weeks. Thirty-one percent of the men on arginine — but only 11.7% of the men on the placebo — reported significant improvement in sexual function. Objective variables remained unchanged. The men who responded to the arginine had lower levels of NO at the beginning of the study.50
The combination of these two NO-enhancers has proven to be a promising approach to treating ED. In a study of 40 men, one month of arginine ingestion led to normal erections in only a non-significant 5% of the men. But when 40 mg of Pycnogenol twice a day was added in the second month, 80% of the subjects were restored to normal erections. And when the dose was increased to 40 mg of Pycnogenol three times a day, the number of men who attained sexual ability increased to 92.5%. The researchers concluded that the combination of arginine and Pycnogenol causes significant improvement in ED without adverse effects.51

These promising results have been duplicated in at least two more rigorously designed, double-blind studies. In the first, 111 men with mild-to-moderate ED (IIEF score between 11 and 17) were given either a placebo or a combination product containing 40 mg of Pycnogenol and 1400 mg of arginine (Prelox®, Horphag Research; Geneva, Switzerland) twice per day. After three months, the Pycnogenol/arginine group’s score on the IIEF had increased significantly from 15.2 to 25.2; the placebo group improved from 15.1 to only 19.1. And, after six months, the Pycnogenol/arginine group’s score had continued to rise to 27.1, while the placebo group had started to drop slightly to a score of 19. The improvement in the Pycnogenol/arginine group was significant compared to the placebo (P<0.05). Additionally, there was a significant improvement in orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction in the Pycnogenol/arginine group (P<0.05) compared to the placebo group. Testosterone levels increased significantly from 15.9 to 18.9nmol/L (P<0.05), but barely at all in the placebo group.52

In the second double-blind study, men with mild-to-moderate ED were given a supplement containing 60 mg Pycnogenol, 690 mg L-arginine, and 552 mg aspartic acid or a placebo each day for eight weeks. Total scores on the IIEF-5 improved in the supplement group. There was “marked improvement” in the hardness of erection and satisfaction with sexual intercourse items of the IIEF-5. There were no adverse reactions. The researchers concluded that Pycnogenol combined with L-arginine is safe and effective in mild-to-moderate ED.53

Rhodiola rosea root. Rhodiola (Rhodiola rosea, Crassulaceae) is a traditional herb of increasing popularity for its adaptogenic activities. It is known for its ability to help reduce symptoms of stress and fatigue, among other properties. With respect to ED, in one open clinical trial, 35 men who suffered from ED, premature ejaculation, or both, took 150-200 mg of rhodiola root extract for three months; 26 of them responded with substantially improved sexual function.54

Eurycoma longifolia. Another herb with a name that reflects its traditional use is longjack root, more commonly known by the Malaysian name tongkat ali (Eurycoma longifolia, Simaroubaceae). This herb is commonly found in Southeast Asia. In Malaysia, it is commonly employed as an adaptogen for general well-being and specifically as an aphrodisiac with claims of benefit for ED. In a recent double-blind, placebo-controlled clinical trial, researchers gave either 300 mg of freeze-dried standardized water root extract of E. longifolia(Physta®, Biotropics Malaysia Berhad, Shah Alam, Selangor, Malaysia) or a placebo to 109 men with no ED or only mild ED for 12 weeks.55 Scores on the IIEF were a secondary endpoint. There was a significant improvement in erectile function in the E. longifolia group compared to the placebo (P<0.001). There was an 8.7% increase in the ability to attain an erection and a 7.2% increase in penetration ability.

The important limitation of the study, however, is that its population consisted of healthy men with no or only mild ED; all subjects fell within the “no dysfunction range.” This limitation leaves two possibilities: Either E. longifolia enhances erectile function in healthy men with unknown benefit for men suffering from ED, or the study shows that E. longifoliaenhanced erectile function and may have shown even more positive results but, because the subjects were already healthy, there was limited possible benefit to be achieved by administering the herb. Future research will help clarify this matter.

Ashwagandha root. When stress and anxiety are contributing factors, nervine herbs like ashwagandha (Withania somnifera, Solanaceae) and oats (Avena sativa, Poaceae) may be helpful. Ashwagandha is an adaptogenic root that may be useful for sexual problems related to nervous tension. It has long been used in India as a rejuvenating aphrodisiac. Ashwagandha contains withanolides, which act as hormone precursors that can convert into, and perhaps balance, human hormones.56

Oats. Oats are among the most effective tonic herbs for the nervous system, traditionally considered to support the nervous system while relaxing it, and have long been used as an aphrodisiac for boosting sexual vitality. Unpublished research at the San Francisco Institute for Advanced Study of Human Sexuality has found oat extract to be beneficial. A double-blind study found improved firmness of erection in men with no sexual dysfunction. A second study gave 300-600 mg oat extract to 30 men with ED. Nineteen of them experienced a partial or complete response, with erection ability returning to pre-impotence levels in all 19.57 Though there is some evidence for oats as an herb for ED, the basis for the use of oats remains mostly folkloric.58 However, several prominent herbalists and herbal researchers continue to endorse the use of oats as an appropriate nervine for stress and anxiety related to ED.59-61

Yohimbe. The African tree bark yohimbe (Pausinystalia johimbe, Rubiaceae) is a traditional aphrodisiac from which the alkaloid yohimbine, a recognized and previously employed pharmaceutical agent for impotence, is derived. Yohimbe is considered effective, but its myriad adverse effects, including blood pressure and heart rate-increasing properties, inhibit its utility.62,63

Conclusion
Though many of the attempted folkloric solutions to ED seem improbably amusing, time and science have strongly suggested, and, in some cases, provided compelling evidence that there is some truth in the traditions. There is reasonable evidence supporting the notion that traditional herbs, such as horny goat weed, muira puama, and maca, may help improve symptoms of ED. And for some herbs — particularly Korean red ginseng, Ginkgo biloba extract, and the patented French Maritime pine bark extract known as Pycnogenol (especially when combined with L-arginine) — the scientific support is quite promising. Science seems to encourage the hope that for men suffering from ED, whether the condition is of physical or psychological origin, there is a safe and effective natural, non-pharmaceutical path to improvement.

Linda Woolven is a master herbalist, certified acupuncturist, and solution-focused counselor with a practice in Toronto. She is the author of several books, including Smart Woman’s Guide to PMS and Pain-free Periods (John Wiley & Sons, Ltd., 2008). Together, Woolven and Ted Snider, a natural health researcher and writer, are the authors of Healthy Herbs: Your Everyday Guide to Medicinal Herbs and Their Use (2006), The Family Naturopathic Encyclopedia (2011), and Sex & Fertility: Natural Solutions (2012), all published by Fitzhenry and Whiteside Limited. They also publish The Natural Path newsletter. Woolven and Snider can be reached at their blog at www.thenaturalpathnewsletter.com.

*Mention of the name of a company that manufactures and/or sells a particular product or ingredient in a product referred to in this article is not a promotion or endorsement of said ingredient, product, or company. Mention of such information is consistent with the general editorial policy of the American Botanical Council in reporting pharmacological and clinical research on botanical preparations where there is often variability in the chemistry of such ingredients or preparations from one brand to another.

†A peer reviewer of this article with expertise on maca has stated that there are up to 13 different phenotypes of maca — sometimes referred to as red, black, or yellow maca — each with various chemical profiles, and thus potentially varying biological activity. Such distinctions are seldom made in the pharmacological and clinical literature on maca, and thus, unless a specific phenotype is mentioned in the original research paper, such information is not included in this review article.

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