Road Test: Erectile Dysfunction
History will relate that it was the chemists of drug giant Pfizer who first brought men ‘s most intimate problem out from under the bedclothes into the light of day with the invention of Viagra in 1998. But Pfizer ‘s greatest achievement was to turn male impotence from a guilty secret into an everyday medical condition. For that, it needed a more clinical name – ‘erectile dysfunction’ (ED) – and drugs for ED have taken their place among statins and beta-blockers as some of the most heavily advertised medications in the world.
Viagra has also had a major impact on the herbal medicines industry, ridding aphrodisiacs of their sleazy back-street image, and freeing up herbal manufacturers to search the botanical pharmacopoeias for long-forgotten remedies. Today, just six years after Viagra was launched, there are literally hundreds of herbal ED products on offer.
What is ED?
While ED can strike at any time, its incidence increases with age; indeed, as many as half the men aged 40-70 may be affected (J Urol, 1994; 151: 54-61). Once thought to be psychological, the medical pendulum is swinging towards a more physical explanation. One major cause is believed to be atherosclerosis (hardening of the arteries), which blocks blood flow to the penis, thus impairing erections. Other possible causes are ischaemic heart disease, high blood pressure or cholesterol, diabetes, kidney disease, chronic alcoholism, multiple sclerosis, smoking, hormonal imbalances, prostate disease and depression. The side-effects of prescribed drugs account for around 25 per cent of ED cases (Adv Drug React Toxicol Rev, 1999; 18: 5-24). Ironically, given that depression can cause ED, antidepressant drugs are particularly prone to interfere with sexual functioning.
There’s a simple test to check if ED is psychological or physical. Thanks to drug-company chemists, we now know a lot about the physiology of erections. It seems that the normal non-erect penis requires constant control by the sympathetic nervous system (which regulates involuntary physiological reactions, such as an ‘adrenaline rush’) to stay flaccid. Sexual stimulation switches off sympathetic control while releasing nitric oxide gas (NO) into the penis. By a complex chemical chain reaction, this relaxes the arteries, which increases blood flow to the spongy tissue in the penis, thus producing an erection.
Erections usually require at least some mental participation but, if the sympathetic system is ‘off’, spontaneous erections will occur. This happens most often while asleep, particularly during episodes of rapid eye movement sleep. These nocturnal erections are believed to be a kind of penis maintenance system (Sci Am, 2000; 283: 70-5), but they also serve as a useful diagnostic test for ED. Poor sexual functioning with satisfactory nocturnal erections suggests a psychological, rather than physical, cause for the ED. However, ED is often a bit of both, particularly as men get older. That is when many of them may need a chemical leg-up, though conventional drugs can bring as many risks as benefits
Herbal helpers
Over the thousands of years that mankind has been studying the medicinal effects of plants, a number of botanical sex aids have been discovered. Back in the 13th century, when Marco Polo returned from China, one of the most prized items in his exotic cargo was ginseng, claimed by the Chinese to be a powerful stimulant – of all parts of the body, including the genitalia. But the world had to wait for more than 700 years for ginseng’s aphrodisiac qualities to be proven scientifically. In 1995, Korean doctors tested ginseng on 90 men with ED in a clinical trial, and found that it improved erections in 60 per cent of cases compared with 30 per cent with a placebo (Int J Impot Res, 1995; 7: 181-6).
Those findings were later replicated by another Korean medical group in a double-blind placebo-controlled trial in which 45 impotent men were given 900 g of ginseng three times a day for eight weeks. Again, 60 per cent were improved (J Urol, 2002; 168: 2070-3).
The herb is believed to work by dilating blood vessels, promoting NO production and stimulating the part of the brain involved with sexual functioning (Ann NY Acad Sci, 2002; 962: 372-7). Although clinical trials so far have been small, the evidence seems sufficiently good to rate high-dose ginseng as having a “moderate” effect on ED (Altern Med Rev, 2004; 9: 4-16).
Ginkgo biloba, like ginseng, is also an adaptogen with Eastern sexual promise, though hard scientific data are somewhat lacking. Although Ginkgo can improve blood circulation in the brain and legs, it may not do much for the genitals. One study found that 240 mg/day helped ED (J Sec Educ Ther, 1991; 17: 53-61) whereas another found no effect whatsoever (J Urol, 1998; 159 [suppl 5]: 240).
Most Ginkgo research has focused on ED caused by antidepressants, a connection revealed by accident in old people ‘s homes, when men being given both Ginkgo for memory loss and SSRI drugs for depression reported improved erections (J Sex Marital Ther, 1998; 24: 139-43). However, in subsequent small-scale clinical trials, the results were mixed, with some showing benefit, but others not. In lab tests, however, very high doses of Ginkgo have been shown to affect penile tissue, probably by releasing NO (J Urol, 1996; 156: 1876-80).
A number of less familiar botanicals have been proven to pack more punch. The one in longest use in the West is the yohimbe tree (Pausinystalia yohimbe). Known to African witch doctors for centuries, it began to be used by Westerners as a cure for impotence in the 1920s. Its active ingredient is yohimbine, an alkaloid that acts as an alpha-2-adrenergic receptor antagonist. That means it directly blocks sympathetic inhibition of erection while triggering the production of NO (J Urol, 1997; 157: 2356-60). Of the dozen or so clinical studies of yohimbine, most have shown positive effects (J Urol, 1998; 159: 433-6). In one, when 61 men were given 5.4 mg of yohimbine hydrochloride three times daily for eight weeks, 37 per cent reported “restoration of erection” compared with 13 per cent among those taking a placebo (Sex Marital Ther, 1989; 4: 17-22).
However, yohimbine can also cause headache, sweating, agitation, high blood pressure and sleeplessness – but these are relatively mild and infrequent. A more serious downside is that high doses can interact dangerously with some prescription drugs and possibly alcohol. Yohimbine potency can be boosted by the addition of another natural product, the amino-acid L-arginine – 6 g of L-arginine plus 6 mg of yohimbine taken ‘on demand’ increases the effect of yohimbine by a few percentage points (Eur Urol, 2002; 41: 608-13).
L-Arginine is the precursor of NO, and a faulty L-arginine-NO pathway is a contributing factor to ED (Drugs Today [Barc], 2000; 36: 163-74). In one study, over 30 per cent of men who received 5 g/day of L-arginine reported improved erections (BJU Int, 1999; 83: 269-73). The dose, however, is important: 1.5 g/day, for example, appears to have no effect whatsoever (Urol Int, 1999; 63: 220-3). L-Arginine potency is also increased by combining it with maritime pine tree (Pinus maritima) bark. This tree has proved to have remarkable properties: it strengthens arteries, improves blood circulation and is a potent antioxidant. It also increases NO, hence the connection with ED.
Pinus maritima bark extract is marketed by a number of companies as Pycnogenol, and was recently clinically tested for its effects on ED. Bulgarian researchers gave men 80 g/day of Pynogenol plus a low dose (1.7 g) of L-arginine, and noted a dramatic improvement in sexual function after a month in 80 per cent of the men, without side-effects (J Sex Marital Ther, 2003; 29: 207-13). Earlier evidence from Slovakian doctors has suggested that L-arginine may not be necessary, and that 120 mg/ day of Pycnogenol alone will do the trick (Nutr Res, 2003; 23: 1189-98).
A better-known aphrodisiac is maca (Lepidium meyenii), a Peruvian root vegetable with legendary sexual powers. Experiments have confirmed that it can improve sexual performance in rodents (Andrologia, 2002; 34: 177-9), but human trials are limited to just one study on men that did not test ED itself, but “self-perception on sexual desire”. The results in this case suggested that 1500 mg/day is the minimum necessary to obtain any effect (Andrologia, 2002; 34: 367-72). Tribulus terrestris, the puncturevine, is another aphrodisiac found mainly in India and Pakistan. Various animal studies have substantiated some of its claimed sexual powers (J Alt Complement Med, 2003; 9: 257-65) but, once again, good data in humans are lacking. Nevertheless, furostanol saponins, the vine ‘s active ingredients, are thought to convert to dehydroepiandrosterone (Int J Impot Res, 1997; 9: S64), or DHEA – the famous rejuvenator – which has evidence to support its use in ED. In one small trial, 50 mg/day of DHEA improved overall sexual functioning (Urology, 1999; 53: 590-4).
Other celebrated herbal aphrodisiacs include damiana, muira puama, catuaba, Avena sativa (wild oats) and Epimedium (horny goat weed) but, so far, any supportive evidence is either very poor or non-existent. Because ED has such a huge psychological component, any erectile aid must also be tested against a placebo before it can make any claims to work.
The products
In our road test of natural remedies for ED, we have looked at some of the UK’s best-selling natural products. Many of these have not yet found their way into mainstream chemists or even healthfood shops, but are instead available by mail order and over the Internet. In addition, many originate in the US. Without clinical trials to back the claims made by these products, we have only their stated ingredients from which to draw any possible conclusions. While most of these do contain some proven herbs, these are not always included in therapeutic amounts. While price is not usually a major concern for men with ED, when purchasing any products, it is important to weigh up the value of the treatment in other ways. Always check that the active ingredients such as L-arginine and yohimbe are in therapeutic amounts. To assess these products, we ‘ve looked at the ingredients, their amounts, the overall cost of the product, the presence of any clinical data to support its use and how quickly they claim to produce results.
ArginMax For Men
Distributor: Daily Wellness Company
Price: $24.79 for 180 capsules
Rating: *****
This is the leader of the pack, as it’s the only product supported by a full-scale clinical trial. The formula contains what appears to be ample quantities of L-arginine, ginseng and Ginkgo, along with 13 vitamins and minerals.
A pilot study involved giving 25 men with mild-to-moderate ED ArginMax for four weeks. Of the 21 who completed the study, 89 per cent “improved in ability to maintain an erection during sexual intercourse and 75 per cent improved in satisfaction with their overall sex life. No significant side effects were noted ” (Hawaii Med J, 1998; 57: 741-4).
The product’s downside is that it doesn’t work immediately, and may take up to four weeks to have any effect. The daily recommended dose is six capsules, which works out to around $40 a month. It does, however, come with a 60-day money-back guarantee. The label lists all ingredient amounts per six-capsule daily serving.
BetterMAN
Manufacturer: Interceuticals Inc
Price: 40 capsules for $39.99
Rating: ****
Made in the US, this is hard to find in the UK unless you order it over the Net. A “proprietary blend” of 18 Chinese herbs, including ginseng, it gets near-top ranking as it is also backed up by some research evidence, albeit in rats (J Urol, 2000; 164: 1798- 801). Other studies in humans are unpublished, but have found that as much as 70 per cent of men reported better erections with this product. Like ArginMax, BetterMAN is not a quick-response product. In one survey, 70 per cent of men reported satisfactory erections during the third month of use. This means that, at the dose of two capsules daily, you ‘d have to buy five bottles (at a cost of $199.95, or around lb114.25) before you see any benefit.
Passion Rx
Manufacturer: Physician Formulas Inc
Price: $27.95 for 30 capsules
Rating: ***
This contains antioxidants and botanical aphrodisiacs, including yohimbe (30 mg), Tribulus terrestris and maca, and claims to work for both men and women. Although the amount of yohimbe looks high, it probably only represents about 1 mg of the active alkaloid yohimbine. Clinical trials suggest that 16 mg/day of yohimbine are necessary for a response, but there may be a booster effect from the other ingredients, so this might well work. The manufacturer claims that most people see results within one to four hours of taking it.
Supra VX 60
Distributor: Up For Life
Price: lb59.98 for 60 tablets
Rating: ***
A combination product containing six ingredients, including maca and L-arginine, this seems promising. However, the manufacturer hasn ‘t specified the amounts of each ingredient, so there’s no way to know if there’s enough in each pill to have an effect. Sublingual (under the tongue) dosing suggests that it could work quickly. This comes with a “full money-back guarantee”, so this product may at least be worth a try.
Herbal V
Distributor: Herbal V
Price: lb29 for 30 capsules
Rating: **
For this combination of eight herbs, including yohimbe extract, ginseng and Tribulus terrestris, there is some evidence of working. However, the quantities may be too small to have any real medical effect, to judge by clinical-trial evidence.
Also, be aware that some variations of Herbal V use androstenedione, which makes testosterone. This may have unexpected health effects, including increased oestrogen in men (JAMA, 1999; 281: 2020-8; JAMA, 2000; 283: 779-82). Ironically, impotence is also among its list of side-effects. If this product works, its main advantage is its rapid action, claimed to be as quick as one hour after dosing.
V-RX V
Sexual Stimulant
Distributor: Planet Health Online
Price: lb20 for 4 capsules
Rating: *
Described as a “fast-acting erection boosting supplement developed through years of research into Chinese herbal medicine “, the only ingredient that appears to have been properly studied is the root of the plant Butea superba. In a single trial, 1000 mg/day of Butea improved ED in 80 per cent of men (Asian J Androl, 2003; 5: 243-6). However, this product only offers 50 mg per capsule. It ‘s also very expensive.
Vitavigour
Distributor: Healthy Direct
Price: lb17.95 for 90 capsules
Rating: *
This product is a blend of five ingredients, including 75 mg of Ginkgo biloba and “the equivalent of 500 mg” of Tribulus terrestris, which sounds like a lot. But since the therapeutic dose of puncturevine is not known, the product may or may not work.
- This article first appeared in the January 2005 edition of Proof!.
