L-Arginine

L-Arginine - History

Arginine was first isolated in the late 19th century from the lupin plant by Swiss chemist Ernst Schultze. [1]

Is L-Arginine an Aphrodisiac?

Much investigation has been done into L-Arginine's medicinal qualities in recent years - including a great deal of research into its potential to treat Erectile Dysfunction. For example, search of Pubmed [3] (the medical database of the US. National Library of Medicine) in 2010 for "arginine erectile" revealed 308 entries and these can easily be viewed.

Nitric oxide is an essential part of the erectile function in men through the fact that it causes vasodilation - expansion of arteries. It is essential for the body's regulation of blood flow and blood pressure. [4]

In males, the blood vessels in the penis are surrounded by smooth muscles which act as "valves". Normally these muscles are in a contractile state, meaning that blood flow is routed back to the deep dorsal vein. [5] Nitric oxide is used in the body as a signalling mechanism which, through a complex process [6], causes the smooth muscles to relax, allowing full blood flow to the penis and producing erection.

One of the ways nitric oxide is created in the body is that it is synthesized from L-Arginine and oxygen by nitric oxide synthase (NOS) enzymes. Arginine is an immediate precursor of nitric oxide. [1] [7]

The other way NO is created in the body is through the denitration of nitrates such as glyceryl trinitrate (nitroglycerin) - and it's interesting to note the recent development of a new type of Durex condom, the CSD500, to be launched in late 2010 - which contains glyceryl trinitrate in the teat and has been clinically proven to improve penile size, erection firmness and duration of erection. [8]

Overall, there are several ways in which Nitric oxide can be artificially increased in the body - and one of the famous ones is through the use of medicines such as Sildenafil citrate, (aka the ever-controversial "blue pill" with the name beginning with V). However, this has been noted to have numerous possible side effects.

The general conclusion in the medical community seems to be that supplementation with L-Arginine by itself may typically create some, but not dramatic improvement in male sexual function; but in combination with certain other products, much more significant results have been noted. [1]

In combination with Pycnogenol (a trademarked water extract of Maritime Pine bark), studies have shown that L-Arginine can greatly assist in cases of Erectile Dysfunction. A 2003 study on human males at the Seminological Laboratory SBALAG, Maichin Dom, Sofia, Bulgaria, found that after 1 month of treatment with just L-arginine, statistically insignificant benefit to erectile function (5% of subjects) was noted. However, after another month of treatment with a combination of L-arginine and Pycnogenol, the number of men with restored sexual ability rose to 80%. After a further month of treatment, 92.5% of the men experienced a normal erection. No side effects were noted. [9]

Maritime Pine bark extract contains proanthocyanidins, which have been shown to increase the activity of the NO-synthase reaction - so it makes sense that a combination of this with a NO precursor, L-Arginine, would have the desired effect. [6]

L-Arginine has also been used in combination with Yohimbine as a treatment for ED. There is a significant body of science in support of this: For example, a 2002 double-blind, placebo-controlled, three-way crossover, randomized clinical trial at the Urology Department of Hopital Foch, Suresnes, France, found that on-demand oral administration of a combination of 6g L-arginine glutamate and 6 mg yohimbine, was effective in improving erectile function in patients with mild to moderate ED. The combination of Yohimbine and L-Arginine scored better than just Yohimbine alone.[10] See also [11] for another study of Yohimbine / L-Arginine combination.

L-Arginine safety

It has been stated by [12] that L-Arginine supplementation should not be used by heart attack patients.

L-Arginine is widely available as a nutritional supplement in the USA and other countries.

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