Figure 1. The corpus spongiosum is located between
the two corpora cavernosa and contains the urethra.
A Natural Alternative to Viagra
With the commercial release of Viagra®, ribald humor took center stage, and people everywhere were talking about impotence and erectile dysfunction. Immediately after its introduction to the public, references to the "10-dollar pill" were found everywhere: from The Tonight Show to The New Yorker magazine, from The Simpsons to the front page. All at once, it was okay to talk about sexual dysfunction, even if you were a former presidential candidate. And why shouldn't it be? After all, a significant number of men suffer from this inglorious condition. In 1993, the National Institutes of Health reported that 12% of men under the age of 45, 20% of men around age 60, and 50% of men at age 75 experience erectile dysfunction - in all, 30 million men in the U.S. alone.1
SERIOUS SIDE EFFECTS OF VIAGRA
You can bet that those 30 million men were delighted when Viagra came
on the scene. But for some men with erectile dysfunction, the bloom was
off the rose in short course. One report estimates that up to 50% of those
who have tried Viagra find it ineffective in producing an erection.2
In addition, men with cardiovascular conditions are warned against taking
this medication, as it can induce severe cardiac complications by enhancing
the effect of the nitrates used to treat their disease. Moreover, by the
end of 1998, 80 heart-related deaths had been reported in men taking Viagra,
most of whom were elderly or had additional health problems.3
These data generate nagging questions about the safety of Viagra, leading
researchers to explore other, safer methods to help men with performance
problems.
THE BIOLOGY OF AN ERECTION
An erection occurs when the smooth muscle cells of the penile arteries
relax, allowing an increased, rapid flow of blood into the penis. This
causes it to enlarge and become tumescent. Imagine an inflated balloon:
filled with air, it's turgid and stiff. When the amount of air is reduced,
the balloon becomes limp, or flaccid.
The erectile process is under strict biological control, generally occurring - during waking hours - only in response to a sexual stimulus. But what is the signal that starts the entire mechanism? With sexual excitement, the natural process by which the body's amino acid L-arginine undergoes a chemical reaction that releases nitric oxide is accelerated, setting a complex chain of events into motion. Nitric oxide stimulates guanylyl cyclase, a protein, to produce cGMP, a small molecule present in the smooth muscle cells. cGMP induces relaxation of the cells, allowing an inflow of blood to the corpus cavernosum, the spongy tissue of the penis. Engorged with blood, the tissue stiffens and produces an erection.
Figure 1. The corpus spongiosum is located between
the two corpora cavernosa and contains the urethra.
Have you ever wondered why erections don't last long? In part, they're time-limited because smooth muscle cells possess a protein called phosphodiesterase (PDE), which steadily breaks down cGMP, making it inactive. When cGMP levels fall, the muscle cells lose their relaxation and can no longer accommodate the abundant blood flow necessary for erection. As a result, blood recedes from the tissue, and flaccidity ensues. Interestingly, many men have fairly active phosphodiesterase levels in the corpus cavernosum. This is bad news if achieving an erection is your goal, because the smooth muscle cells can't relax, thereby short-circuiting the erectile process. As a phosphodiesterase inhibitor, Viagra counteracts phosphodiesterase function, elevating cGMP levels, which results in smooth muscle cell relaxation, and - voila! An erection.
THE ARGININE ALTERNATIVE TO VIAGRA
Is Viagra the only way to treat erectile dysfunction? Based on the
biological mechanism discussed above, it is clear that any approach that
can elevate cGMP levels in smooth muscle tissue may be useful in restoring
normal erectile capacity. Consider, for example, the possibility of increasing
the amount of nitric oxide in the body.
Since 1986, this gas molecule has been considered an important player in the erectile process, prompting extensive research on its production and role in the relaxation of muscle cells. In fact, research that identified the nitric oxide signaling pathway led to the Nobel Prize for Physiology and Medicine in 1998.
To raise the level of this molecule that is so crucial to the erectile process, you can increase the body's supply of arginine, which is its primary source. However, the reaction occurs only in the presence of a special protein - nitric oxide synthase (NOS) - a molecule that is especially abundant in penile tissue.
The possibility that oral arginine intake improves erectile response was first investigated in animal models. When the diets of older rats were supplemented with arginine, nitric oxide synthase activity increased, producing increased nitric oxide levels, which caused improved erectile response.4 The authors of this study suggest that dietary supplementation with arginine may lead to improved sexual performance in humans as well.
ARGININE IMPROVES SEXUAL PERFORMANCE IN HUMANS
The first evidence that oral supplementation with arginine leads to
improvement in human sexual function came from a short-term study in 1994,
which employed few patients and relied on patient self-assessment.5
Though encouraging, it provided little solid data. It did, however, yield
a positive correlation between arginine supplementation and sexual performance
and satisfaction.
|
and Vitamin B5 Supplementation While arginine is vital for the production of nitric oxide, it's not the only compound that may contribute to improved sexual performance - choline and vitamin B5 (pantothenic acid) also play important roles. Choline is a precursor to acetylcholine, an important neurotransmitter in the erectile process.8 Research has demonstrated that raising the level of choline in the corpus cavernosum tissue results in increased acetylcholine production,9 indicating that higher choline intake may lead to enhanced sexual response. Indeed, smooth muscle tone is associated with acetylcholine as well as nitric oxide,10 and acetylcholine, along with arginine, is considered an "erectogenic" agent.11 Vitamin B5, an essential compound required by all cells for optimal function, is instrumental in many enzymatic activities and acts as a cofactor in the production of acetylcholine. The vitamin is also involved in the production of steroid hormones such as testosterone. Cumulatively, these supplemental compounds help to fortify the cellular tissues involved in the erectile process. |
These intriguing findings were supported by a more recent, larger study conducted at the Department of Urology and Nephrology at Tel Aviv University in Israel. Fifty men with confirmed erectile dysfunction were administered either a placebo or 5 g/day arginine for six weeks.6 Thirty-one percent of the subjects receiving arginine reported subjective improvement and satisfaction in their sexual performance. In the placebo group, only 12% of the men noted improvement in sexual function. This study was closely monitored in a clinical setting, employing the standard double-blind design (neither the doctors nor the patients knew who received the placebo and who received the arginine). Also importantly, at the 5-g daily dose, no significant side effects occurred in any of the patients throughout the entire duration of the study.
The percentage of patients reporting improved performance (31%) may not sound like an impressive number, but keep in mind that up to 50% of Viagra users report no benefit from taking this prescription medication, which has proved to cause serious side effects. Although arginine has generally been studied far longer and more intensively than Viagra - for its general applications for immune-function enhancement and growth hormone-release - its effect on sexual function is just coming to the fore. It may turn out that larger doses of arginine will increase the positive response rate even more than what has been found to date.
It is important to note that not all the literature supports the use of arginine in improving sexual performance in men. One study, in which diets were supplemented with only 1.5 g/day of arginine, reported no improvement in sexual performance.7 However, the reduced amount of arginine (compared with the Tel Aviv research) may have caused these disappointing results; higher doses may well have confirmed the earlier study's promising statistics.
OTHER BENEFITS OF ARGININE
In addition to its vital role in erectile function, with its ability
to produce nitric oxide, arginine also plays a pivotal role in other biological
processes. For example, nitric oxide is also fundamental to immune response,
cardiovascular health, and memory, though it activates different cellular
pathways in each of these processes. In another important body function,
arginine increases the production of growth hormone, an essential molecule
that decreases with age. Because growth hormone is necessary for wound
healing and muscle-mass acquisition, the age-related decrease in the production
of this hormone may explain why wounds take longer to heal and gaining
muscle mass is more difficult in later life. Clearly, the benefits of arginine
supplementation become apparent when you consider the myriad roles that
this essential molecule plays in human health.
TURN BACK THE CLOCK
As men age, the likelihood of erectile problems increases. Remember
the numbers - 12% of men under 45, 20% of men aged 60, and 50% of men aged
75 report erectile dysfunction at some point in their sexual lives.
Why is this? Aging is the most likely culprit - arterial blood flow to the penis decreases as men grow older. In many cases, this decreased flow can be traced to atherosclerosis, diabetes, cardiovascular complications, or other age-related declines, but the simple truth is that the rate of blood flow to the penis generally diminishes with age, and impaired blood flow substantially decreases the occurrence of erection. High cholesterol, high homocysteine levels, stress, smoking, poor diet, and lack of physical exercise all exacerbate this situation. So, if you want to enhance and preserve your erectile function, improve your cardiovascular fitness through regular exercise, stop smoking, eat right, and enjoy life. And consider throwing in a little arginine to help jump-start your body's production of nitric oxide.
References