There is an old saw about sex and men that says a man should not be concerned the first time he can’t get it up the second time, but the second time he can’t get it up the first time, he may have a problem. Prior to 1998, Erectile Dysfunction (ED), or impotence, as it was known, was a problem most men knew existed, but happened to other guys, especially other old guys. Treatments for impotence, if they existed, were even less well known. In that year, Pfizer Pharmaceuticals introduced America to Viagra (sildenafil citrate), a new type of drug designed to prop up a man’s flagging performance and at the same time brought the whole subject of male sexual dysfunction out of the shadows. Suddenly we found out that millions of red-blooded American men were only getting their flags to half-mast. After the jokes subsided, Pfizer quietly sold millions of their little blue pills.
Once it was out in the open, the topic of male sexual health eventually turned from dysfunction to performance.
To see this clearly, one need only consider the advertising for Viagra and the similar drugs that have followed. In 1999, an elderly Bob Dole, who had been beaten soundly for the Presidency by a man who, we knew by then, didn’t need any pharmaceutical help to keep his –err—“cigar” lit, appeared on television talking in a very serious way about Erectile Dysfunction. The message was: this medicine can take a beaten old man and make him whole again. Fast forward to this year when a recent advertisement for Bayer Pharmaceutical’s Levitra (vardenafil), a Viagra competitor, features a young, successful-looking, attractive woman telling us that her equally young, healthy guy takes it so he can have the “quality of response” he expects. Clearly we have moved from just fixing what was broke to wanting to tweak things out for maximum performance.
Today, young healthy men who have never had a weak moment between the sheets, are buying and using not only prescription ED medications but also a whole host of OTC supplements to enhance their sexual performance. And why not? Many of us take fistfuls of supplements to fine tune the function of our quadriceps, biceps and other parts of our anatomies. Why shouldn’t we be interested in a performance supplement for our love muscle?
If you are interested, you will find no shortage of companies ready to sell you some lotion or potion to make you a superstar in bed. A Google Search for “Male Sex Enhancer” returns almost 200,000 responses. Sadly, most of the products out there have little or no science to back them up, are seriously under dosed, or are formulated based only on folkloric history of random herbs. Consequently, they are unlikely to increase the performance of anything other than the manufacturer’s balance sheet. The good news is there are a few supplements that are backed up with actual clinical research, or at least sound scientific theory. These supplements really have the potential to do for men in the bedroom what creatine did for them in the gym. This article will look at some of the most effective male sexual supplements and the science behind them.
To understand how these supplements work, we will need to take a brief look into the fairly complex process of male sexual arousal. Complex you say? As amazing as it may seem to anyone in possession of a penis, the process behind getting an erection is not as simple as the user interface would lead you to believe.
First, a little anatomy. The penis is an unusual piece of engineering in that it is the only part of the male anatomy that is hydraulically actuated. There is actually very little muscle associated with an erection. This has the handy effect of allowing the penis to grow firm enough for intercourse when needed and then to return to a flexible form far less likely to be damaged while chasing a wildebeast across the plain, or, leaning over a desk while day trading. This feat is accomplished through the control of blood flow in and out of some specialized sponge-like tissues in the penis called the corpus cavernosum. When the penis is erect, these tissues are engorged with blood like a fully inflated balloon. The control over this process begins in the brain.
When a man becomes sexually stimulated either through physical contact or other sensory stimuli, a signal is sent from the brain to endothelial cells in the penis to release nitric oxide (NO). The NO release causes a rise in cyclic guanosine monophosphate (cGMP), which in turn causes the smooth muscles of the penis to relax and allow a dramatic rise in blood flow. This process is limited by a specific phosphodiesterase (PDE5) enzyme that breaks down cGMP and recycles it. At the same time, the pressure of the now-filled corpus cavernosum compresses the veins that normally drain the blood from the penis so that the penis will remain engorged as long as the release of NO continues. If stimulation is discontinued, the release of NO will taper off and levels of cGMP will follow with the contraction of smooth muscles and a reduction in intercavernousal pressure (ICP). The penis will return to its flaccid state through venous drainage. Ironically, this means that an erect penis is actually a relaxed penis.
If we want to enhance the erectile response, we can look to influence the system at a couple of points. The first is to increase the amount of nitric oxide or cGMP produced in response to stimulation. The second is to impede the breakdown of cGMP by inhibiting the production of PDE5 and a third is to enhance the control signals from the brain itself
Yohimbine HCL is an alkaloid found in the bark of the African Yohimbe plant (Pausinystalia yohimbe) and also in the South American Quebracho tree (Cortex quebracho). Among its many physiological effects, it is a fairly potent alpha-2 andregenic receptor agonist. What this means for erections is that it inhibits a neural feedback mechanism that controls the amount of nitric oxide released in response to sexual stimulation.1, 2 More nitric oxide means more cGMP and, theoretically, a harder erection. Yohimbe bark has a long folk history in Africa as an aphrodisiac and yohimbine HCL was one of the only oral drugs available for erectile dysfunction before the introduction of sildenafil.
Despite its long folk reputation as a potency enhancer, in clinical use, yohimbine had a success rate for treating ED of less than 50%. Perhaps the biggest problem with using yohimbine as a sexual enhancer is its side-effect profile, which can include anxiety, nausea, insomnia, heart palpitations and an inability to urinate. Some people are highly sensitive to yohimbine and will feel some or all of these effects at almost any dose. If you want to try it, and have never used it before, a dose of 5mg of yohimbine HCL is probably a good place to start. Be aware that many products contain Yohimbe Bark extract that may or may not be standardized for yohimbine alkaloid content. Even when using a standardized extract, there are other alkaloids in Yohimbe bark that may be physiologically active. Using a product that only contains only yohimbine HCL reduces (but doesn’t eliminate) the possibility of unwanted side effects.3
This amino acid has become very popular among bodybuilders and other athletes as a vasodilator. In theory, supplementing with l-arginine provides more substrate for the production of nitric oxide (NO) thereby allowing for greater vasodilatation. This only works in the body as a whole if there is a physiological lack of l-arginine, and it would appear from clinical experience, the same holds true for erections. Consequently, the data on the use of l-arginine as a sexual enhancer is mixed. In one well-designed study, l-arginine at a dose of 1500mg/day produced no better results than the placebo in patients with erectile dysfunction.4
Other studies have shown, however, that when used by people with low NO production, it seems to work as an erection enhancer.5 When arginine is combined with other substances that increase NO production, there appears to be a synergistic effect. For example, one study showed when 1700mg of l-arginine was combined with 40mg of pycnogenol (a NO enhancer derived from pine bark) the success rate for the treatment of ED was reported to be 80%.6 Another study looked at the combination of 6g of l-arginine with 6mg of yohimbine HCL and showed a clinically significant effect over either yohimbine alone or a placebo.7
It would also appear that the inhibition of arginase, the enzyme that breaks down arginine, is more effective than simply supplementing with arginine alone when it comes to erections.8, 9,10 This may be the reason for the anecdotal reports of better erections from users of hemodilators containing the arginase inhibitor norvaline, an analog of the amino acid valine. In fact, I suspect norvaline, by itself in sufficient dosages, would make a fairly effective sexual enhancer.
The term ginseng is used generically to refer to three distinct plant species. Siberian Ginseng (Eleutherococcus senticosus), American Ginseng (Panax quinquefolius) and Chinese or Korean Ginseng (Panax Ginseng) all belong to a group of herbs known as adaptogens and all have broad uses in herbal therapeutics. It is the two Panax species that have the longest traditional use as sexual enhancers and have been subjected to scientific study that supports their use and efficacy in the bedroom.
Although ginseng’s exact mechanism of action remains elusive, its physiological effects are thought to be due to the presence of tetracyclic triterpenoid saponins known as ginsenosides in the two Panax species.11 These ginsenosides appear to have an effect both on the neurotransmitters involved in sexual arousal and on the NO/cGMP pathways involved in erection. Although there is also a possible impact on the hypothalamus-pituitary-adrenal (HPA) axis with a corresponding impact on cortisteroid and prolactin levels, ginseng supplementation does not cause a change in testosterone in males.12, 13,14
The big question is does ginseng live up to its reputation as a male sexual tonic? The answer appears to be a qualified yes, but dosage and length of administration appear to be important.15 In a sixteen week, double-blind study using three grams of ginseng per day versus a placebo in men suffering from erectile dysfunction, the ginseng treatment offered significant improvement in erectile quality over placebo.16 Another study also found a significant improvement over placebo, but again only after several weeks of administration.17 The same study also found no changes in sexual response after acute, short-term ginseng administration. So popping a ginseng capsule an hour before sexual activity probably won’t do much for you.
It would appear, therefore, that ginseng has the potential to be useful as a sexual enhancer but must be consumed in sufficient quantities (at least a gram per day) continuously for a period of several weeks to be effective. However, given the fairly low cost and generally positive impact ginseng consumption has on overall health, 18,19 the addition of an adequate daily dose of ginseng for improved sexual performance would seem to be a smart move.
Horny Goat Weed/Epimedium
It’s hard to imagine an herb with a name like this would not be a sexual enhancer. As the story goes, the name came from observations by Chinese goat herders that their animals became exceptionally amorous after grazing on a particular shrub now known to be Epimedium Sagittium. Perhaps due mostly to its common name, Epimedium shows up in many “herbal” sexual enhancers. Like ginseng, Epimedium has been used as a male sexual tonic in Traditional Chinese Medicine for several thousand years and its effectiveness and mechanism of action has been the subject of recent scientific study.
Epimedium appears to impact male sexual performance mainly through the actions of a particular flavonoid known as icariin.20 In animal studies, icariin has been shown to be a selective inhibitor of PDE-5 that is 150% more potent than the drug papaverine, an injectable pharmaceutical used for the treatment of ED.19 In another animal study, icariin was injected directly into the corpus cavernosum of live rats and the effect on intercavernosal pressure (ICP) was measured against injected sildenafil. While both compounds produced a dose-dependant rise in ICP, icariin showed about one-tenth the inhibitory activity of sildenafil.21
While we know that icariin is active in the corpus cavernosum after oral ingestion,22 these studies may help to determine the minimal dose of the herb needed to produce an effect. Sildenafil is commonly dosed between 25mg and 100mg for ED treatment. If we assume that it is approximately ten times more potent than icariin in terms of PDE-5 inhibition, we can make an educated guess that a minimal effective dose of icariin would be at least 250mg and probably closer to 500mg.
Epimedium herb can be found standardized to between 10% and 20% icariin, so the minimal effective dose of the dried herb would likely be 1.5g to 3g. Most available men’s formulas contain less than 500mg of Epimedium herb and less than 50mg of icariin. Unlike ginseng, it would appear that the icariin in Epimedium is effective shortly after ingestion and could be used in a manner similar to pharmaceutical erectogenic drugs.
Aside from inhibiting PDE-5 or boosting nitric oxide, it may also be possible to enhance the brain response to sexual stimulus and thereby improve erection performance. Manipulation of the neurotransmitter dopamine can enhance the “signal strength” along the nerves that initiate an erection, thereby increasing the strength of the response.23, 24 A pharmaceutical dopamine agonist, Uprima (apomorphine), is marketed in Europe as a treatment for ED. Although it is more effective than placebo, in head-to-head tests with sildenafil, it is substantially less effective at producing a satisfactory erection in men with ED. However, in healthy men looking to simply enhance their sexual performance, manipulation of dopamine levels in the brain may have promise.26
Dopamine agonists like apomorphine require a prescription in the United States but dopamine levels can also be manipulated through the oral consumption of the dopamine precursor l-dopa. In fact l-dopa, sold as the drug Levodopa, is used as a pharmaceutical agent to treat dopamine deficiency in Parkinson’s Disease. Over-the-counter, supplemental L-dopa is available as a naturally occurring constituent of the Velvet Bean (Mucuna pruriens). Herbal extracts standardized for l-dopa content can be obtained as high as 99%, or essentially pure l-dopa.
L-dopa is a powerful substance and its use should be approached cautiously. The appropriate dosage of l-dopa is highly variable between individuals and some experimentation will be necessary. A reasonable starting point might be 25mg of l-dopa taken an hour before sexual activity, adjusting the dose upwards to 150mg until the desired effect is obtained. The most common side effect of l-dopa administration is nausea and vomiting and there may also be a harmless darkening or reddening of the urine (Editor’s Note: Sounds charming).
Beyond the supplements discussed above, there are several other interesting compounds that may hold promise for male sexual enhancement. These are just theoretical at this point but are supported by some research.
The male erectile response is blunted immediately after ejaculation; during the “refractory period” no amount of sexual stimulation will result in an erection. The refractory period is fairly short (minutes) in young men but can increase to hours or days as men age. It is likely that the refractory period is due to a release of the hormone prolactin in response to ejaculation.27 In one interesting study of a multi-orgasmic male who had no refractory period, the subject was found to lack the normal post-ejaculation prolactin release.28
It’s possible, therefore, that reducing prolactin production would inhibit this negative feedback mechanism in normal males. The extract of the fruit of the Chasteberry Tree (Vitex Agnus Castus) has a prolactin-reducing effect in human males.29 Regular supplementation with Chasteberry Tree extract may, therefore, have a performance enhancing effect.
Topical minoxidil, the active ingredient in the alopecia drug Rogaine, has been investigated as a treatment for ED. Minoxidil is a smooth muscle relaxant that was used originally as a treatment for hypertension. Although not generally effective as a treatment for ED, several studies have demonstrated that a topical 2% solution of minoxidil applied to the head of the penis improves the strength of the erectile response30, 31. I suspect the same minoxidil solution many healthy men without ED apply daily to their thinning mane may also function as a sexual performance enhancer when applied elsewhere. It’s probably worth noting at this point that minoxidil cannot cause hair growth where there are no hair follicles.
A single placebo-controlled study has shown that the rather obscure Thai herb, Butea superba was effective in treating ED at a dose of just 500mg/day of dried herb taken over a period of three months.32 Although there is no other published literature about the efficacy of Butea, we may be hearing more about this herb as a male sexual enhancer in the future.
There is some evidence that supplemental l-carnitine, especially in the form of propionyl-L-carnitine may have positive impacts on erection quality, particularly in older men. One study of note compared the impact on older men of a daily dose of 2 grams of propionyl-L-carnitine plus 2 grams of acetyl-l-carnitine against 160mg of testosterone undeconate while a third group was given a placebo. The carnitine treatment group showed improved erectile function over either of the other two groups after six months.34 Another study showed that 2 grams of propionyl-l-carnitine significantly augmented the effect of oral sildenafil in diabetic patients with ED.35
We can see that there are some truly viable options for men looking to effectively supplement their sexual performance. Arginine, by itself, is unlikely to be helpful for most men and yohimbine, while generally effective, may have too many side effects for most guys. On the other hand, habitual use of ginseng may be a safe, effective and inexpensive place to start for many. Arginase inhibitors look promising and Epimedium and the icariin it contains appears to have real prospects as an effective alternative to prescription erectogenic drugs if taken in sufficient dosages. Manipulation of the brain’s dopamine levels might also be an effective route for some men. Beyond this there are a few other herbs and supplements that might be worth playing around with. Given the interest in sexual performance as evidenced by America’s appetite for erectogenic drugs (Pfizer had over two billion dollars in Viagra sales alone last year), I have no doubt that the research into OTC supplement alternatives will continue.
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By John Galt