Arginine and Select Phytonutrients Enhance Libido

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A Natural Approach to Enhancing Sexual Libido and Performance

By Jim English

A normal sexual response in men and women begins in the presence of sexually oriented stimulation. When the mood is right, the body responds by releasing a cascade of chemicals that direct the flow of blood into the sexual organs. In women, this leads to engorgement and lubrication of the organs as the body prepares for intercourse. In men, this rush of blood is directed into a pair of pockets, known as the corpus cavernosum, that run inside the shaft of the penis. This inflow of blood is critical to the enlargement and stiffening of the penis.

This engorgement is triggered by a unique neurotransmitter called nitric oxide (NO). Nitric oxide, in turn, stimulates the production of another signaling enzyme called cyclic guanosine monophosphate, or cGMP for short. Under normal circumstances, cGMP signals the smooth muscles surrounding the arteries of the penis to relax and allow blood to flow into the penis. Any condition that interferes with the signaling of these messenger enzymes can quickly lead to the breakdown of the entire process and cause impotence.

Impotence/Erectile Dysfunction 

According to the National Institutes of Health, impotence, or erectile dysfunction, is defined as the inability to attain or sustain an erection adequate for satisfactory sexual intercourse. Experts believe impotence affects between ten and fifteen million American men. In 1985, the National Ambulatory Medical Care Survey counted 525,000 doctor-office visits for erectile dysfunction, and that number has greatly increased since then.

Impotence usually has a physical cause, such as disease, injury, or drug side effects. Any disorder that impairs blood flow in the penis has the potential to cause impotence. It occurs as men age: about five percent of men at the age of forty, and between fifteen and twenty five percent of men at the age of sixty-five experience impotence. Yet impotence is not an inevitable part of aging.

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Viagra 

In 1998, the FDA approved the prescription drug Viagra (sildenafil citrate) as a treatment for men suffering from non-organic impotence due to conditions such as diabetes, radical prostatectomy, spinal cord injury, and vascular disease. Viagra was originally investigated as a potential anti-angina medication based on its ability to release nitric oxide and increase blood flow to the heart. Although Viagra failed as a heart medication, researchers in London became excited when men in the clinical trials reported the frequent occurrence of unaccustomed erections and improved sexual performance.

Following this serendipitous finding (and five years of clinical trials), Viagra was finally granted approval as a treatment for men who had difficulty achieving erections because of conditions such as diabetes, radical prostatectomy, spinal cord injury, and vascular disease.

Viagra was found to help men achieve and maintain erections by (1) enhancing the effects of the neurotransmitter nitric oxide (NO), and (2) maintaining higher levels of the enzyme cGMP, the two key players in penile erection. Viagra does this by selectively inhibiting the enzymes that destroy cGMP, leading to elevated cGMP levels. This, in turn, increases blood flow to the genitals and leads to stronger erections and intensified sensation.

Viagra was found to help eighty percent of men suffering from non-organic impotence. Additionally, Viagra also seems to enhance sexual performance and enjoyment, and reduce the latent period between erections, even in men who have no dysfunction.

Viagra has also gained a reputation with women, which makes sense when one considers that the clitoris, which is structurally similar to the penis, becomes engorged with blood during sexual arousal. Viagra may provide similar benefits to women, stimulating the release of NO, encouraging blood flow and enhancing sexual sensation and orgasm.

Serious Side Effects of Viagra 

While Viagra is effective for millions of men, the side effects for many – facial flushing, headaches, and indigestion – are too troublesome for continued enjoyment. And, more seriously, soon after its introduction, vision problems began to surface in men taking Viagra, leading to warnings for people with retinal eye conditions, such as macular degeneration or retinitis pigmentosa, to use the drug only with caution.

In addition to eye problems, both the FDA and the manufacturer began to issue warnings against taking Viagra with any nitrate-based cardiac medications (i.e., sublingual nitroglycerin tablets, nitroglycerin patches, etc.). Doctors were warned that heart patients should not be treated with nitroglycerin if the patient had used Viagra in the previous twenty-four hours. Additionally, the manufacturer reported several cases where patients who received both drugs died after developing irreversible hypotension (a severe drop in blood pressure).

A Safe Alternative 

As safety issues with Viagra began to arise, researchers once again began to seek out safer alternatives for treating impotence. Many current pharmaceuticals have evolved from the historical search for herbal compounds to cure or reverse sexual dysfunction. Often, traditional nostrums rely on purely magical (placebo) effects, such as the phallic-influenced belief in the effect of rhinoceros horn – which, in fact, offers no benefit to humans and is fatal for the unfortunate rhino. Conversely, many plant-based traditional treatments, using herbs such as damiana, maca, muira puama, tribulus, and yohimbe, have been explored for their effectiveness in treating sexual dysfunction.

L-Arginine 

Viagra works to increase both the levels and activity of nitric oxide, leading to increased cGMP, increased blood flow to the genitals, and more intense sensations. Fortunately, there is a less expensive way to naturally increase the amount of nitric oxide released during sexual stimulation. The key is supplemental L-arginine, the direct precursor of nitric oxide.

In the 1990s, scientists discovered that L-arginine, a non-essential amino acid commonly found in the diet, is an oxidative precursor of nitric oxide (NO). As mentioned previously, nitric oxide is required for achieving and maintaining penile erection. Under conditions in which nitric oxide is produced for a specific physiologic purpose, the concentration of L-arginine (from which it is formed) can be a limiting factor.

Researchers at New York University School of Medicine gave L-arginine to a group of impotent men, and found that six out of 15 men receiving the amino acid claimed an improved ability to achieve erections, while none of the 15 men in the placebo group reported any benefit.

Mucuna pruriens 

L-dopa is a chemical precursor of the neurotransmitter dopamine (which in turn is a precursor of norepinephrine). In other words, the body uses L-dopa to make dopamine. Several lines of evidence link activity of dopamine in the brain with sexual behavior. Generally, it appears that higher levels of dopamine are associated with more sexual interest and vice versa. Increased brain dopamine activity caused by taking the drug L-dopa is believed to be the cause of a ‘hypersexuality’ syndrome in people who take the drug for Parkinson’s disease.

While L-dopa is available only by prescription, you can increase your brain dopamine levels by taking the natural herb, Mucuna pruriens, which is a natural source of L-dopa.

Tribulus 

The herb Tribulus terrestris has been used since ancient times in India as a treatment for both male and female sexual problems. Tribulus has been widely tested for its efficacy in enhancing sperm quality and mobility, and for increasing libido and sexual performance in experimental animals and men. It is also widely used as a body building substance. Tribulus administration results in an increase of Luteinizing hormone (LH) levels by 72%, and free testosterone levels by 41%.

Recently, tribulus has been clinically proven to improve sexual desire and enhance erection. Researchers at the Surabaya School of Medicine and Naval Hospital, Indonesia, studied Protodioscin (PTN), a phytochemical agent isolated from Tribulus terrestris. They found that tribulus works via the conversion of protodioscine to DHEA.

Animal studies are beginning to shed light on how tribulus extracts exert their proerectile effect. Researchers working with New Zealand white rabbits measured the ability of oral tribulus to relax corpus cavernosa tissues – necessary for achieving erections. Their study found that the active ingredient in tribulus, protodioscin, worked by increasing corpus tissue responses to acetylcholine, nitroglycerin and electrical field stimulation. The researchers concluded that the enhanced erections and aphrodisiac effects observed with tribulus were due to increases in the release of nitric oxide (NO) from the endothelium and nitrergic nerve endings.

Muira Puama

Muira puama (Ptychopetalum olacoides) is a Brazilian shrub with a long history in South American folk medicine as an aphrodisiac and sexual tonic for promoting virility and treating impotence.6 Human studies have substantiated the use of muira puama for improving libido and treating erectile dysfunction. In one study conducted at the Institute of Sexology in Paris, France under the supervision of Dr. Jacques Waynberg, 262 male patients experiencing lack of sexual desire and the inability to attain or maintain an erection were treated with 1 to 2.5 grams of muira puama extract a day. Following two weeks of treatment, 51 percent of those suffering from erectile dysfunction reported significant improvement. Additionally, 62% of the patients suffering from loss of libido reported that the muira puama extract had, in the words of the researchers, “a dynamic effect.”

A second study conducted by Dr. Waynberg included 100 men who complained of impotence, loss of libido and sexual difficulties due to ‘asthenia,’ described as fatigue, loss of strength, or debility. Following treatment with Muira puama, 66% of the men reported a significant increase in frequency of intercourse. Of 46 men complaining of loss of desire, 70% reported that treatment with muira puama increased libido.

Another important measure of sexual function, stability of erection during intercourse, was improved or restored in 55% of the patients. Other benefits reported included a reduction of fatigue, improved sleep, and increased morning erections. Treatment with muira puama was much more effective in cases with the least psychosomatic involvement. Of the 26 men diagnosed with common sexual asthenia without noticeable sign of psychosomatic disorder, the treatment was effective for asthenia in 100% of cases, lack of libido in 85% of cases, and for inability of coital erection in 90% of cases.

Choline 

Sexual arousal occurs not just in the genitals but in the whole body and, especially, in the brain. For men, it actually begins when the brain sends impulses down the spinal cord and out to the nerves that serve the penis. These impulses trigger the production of nitric oxide (NO), which causes penile arteries to dilate and the spongy core of the penis to relax and become engorged with blood. The neurotransmitter that carries the sexual message is acetylcholine (ACh). ACh also seems to control sexual behavior through its activity in the brain. For women, ACh is also a very important part of sexual function.

Numerous studies confirm a key role for cholinergic nerve transmission in sexual responses. Simply speaking, with too little ACh, sexual activity goes down. Increase ACh levels, and sexual activity goes up. ACh is involved in the build-up toward orgasm and the urethral and vaginal contractions that occur during orgasm as well as the subjective perception of orgasm intensity and duration.

In addition to its direct role in the sexual response, ACh is also the primary chemical the body uses to transmit signals from nerves to skeletal muscles, the muscles that move the body. You need this chemical for muscular control and proper muscle tone. There is reason to believe that enhancing cholinergic neuromuscular transmission will enhance your energy and stamina by raising your ACh levels and that this can provide indirect sexual benefits by allowing you to perform longer and with more energy.

While drugs can enhance the body’s cholinergic activity, these drugs not only have unpleasant or even dangerous side effects, but are available only by prescription. One way to safely and effectively enhance ACh levels is to take supplements of choline, along with vitamin B5, so that the body will manufacture more ACh.

Vitamin B5 

Vitamin B5, also known as pantothenic acid or calcium pantothenate, actually seems to enhance endurance by two routes. The first is its already-mentioned role in creating ACh from choline. Second, is its role in the energy-producing Krebs’ Cycle, which is vital for all living cells. An early indication that vitamin B5 might increase physical endurance came from a study in which rats were placed into a tank filled with cool (64°F) water and forced to swim until they became exhausted. Prior to their swim, the rats’ diets had included either high, adequate, or deficient levels of vitamin B5. The high-dose rats lasted more than four times as long as those whose diet had been B5 deficient.

Ginkgo Biloba 

Ginkgo biloba is a highly regarded herb that has been proven to improve blood flow, enhance oxygenation of tissues, protect blood vessels from free radical damage, and restore elasticity and tone to the entire circulatory system. These impressive properties make ginkgo biloba especially effective for improving sexual functioning and health in both men and women.

Because circulatory problems are a major factor in impotence, researchers studied ginkgo to measure its effectiveness for treating erectile dysfunction caused by impaired blood flow. In one study, ginkgo was found effective in improving erectile dysfunction in a group of impotent males taking 60 mg of ginkgo extract for six months. Researchers suggested that ginkgo worked by stimulating the release of nitric oxide (NO) which, as described earlier, signals the blood vessels to dilate and sends blood to the corpus cavernosum to achieve and maintain an erection.

Ginkgo’s positive effects on impotence were further established by a second study, reported in the Journal of Urology, in which researchers found that ginkgo was highly effective in helping men achieve and maintain erections. According to the study authors, the improvements were due to the direct effect of ginkgo extract to enhance blood flow in arteries and veins.

Ginkgo as an Aphrodisiac? 

Given ginkgo’s proven ability to dilate blood vessels and improve blood flow to the penis, it is not surprising to note that many aphrodisiac formulas contain ginkgo extract. According to Dr. Stephen Karch, a specialist in cardiac pathology and author of The Consumer’s Guide to Herbal Medicine, ancient Chinese herbalists referred to ginkgo as an aphrodisiac. Karch reports that ginkgo enhances nitric oxide (NO) production. Nitric oxide is the primary messenger molecule that is affected by Viagra, and is the key factor in helping achieve erections by informing certain blood vessels to relax.

Chinese Red Ginseng 

In Asia, ginseng has a long history of use in herbal formulas for the treatment of sexual dysfunction. Recent studies in laboratory animals have shown that ginseng enhances libido and sexual performance. These effects of ginseng may not be due to changes in hormone secretion, but to direct effects of ginseng, or its ginsenoside components, on the central nervous system and gonadal tissues. Indeed, there is good evidence that ginsenosides can facilitate penile erection by directly inducing the vasodilatation and relaxation of penile corpus cavernosum. Moreover, the effects of ginseng on the corpus cavernosum appear to be mediated by the release and/or modification of release of nitric oxide from endothelial cells and perivascular nerves. Ginseng has also been found to affect the central nervous system, significantly altering the activity of hypothalamic catecholamines involved in sexual behavior and hormone secretion. Recent findings that ginseng treatment decreased prolactin secretion also suggest a direct nitric oxide-mediated effect of ginseng on the pituitary. Additional studies lend growing support for the use of ginseng in the treatment of sexual dysfunction and provide increasing evidence for a role of nitric oxide in the mechanism of ginsenoside action.

Conclusion 

A healthy sex life contributes to an improved quality of life and can have profound ramifications on emotional and physical well being. The compounds discussed here have been shown, singly and in combination, to be effective in supporting recovery from sexual dysfunction.

References

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