The prevalence of erectile dysfunction (ED) ranges from 5 to 6 percent in men aged 20 to 39, and is considered an important cause of decreased quality of life among this age group. Moreover, ED is ubiquitous among men aged 40 to 70 years of age, affecting approximately 50 percent of men within this age bracket. Based on recent statistics, the foregoing percentage corresponds to approximately 150 million men worldwide.
ED is generally considered as a manifestation of functional and/or structural abnormality affecting penile circulation. Although modifying lifestyle risk factors can assist, in most cases patients also need medication to improve or correct ED. Phosphodiesterase type 5 (PDE-5) inhibitors have revolutionised the treatment of ED. However, despite their efficacy, they have limitations – especially for patients suffering from diabetes and nerve injury, who show a poor response to PDE-5 inhibitors or become refractory.
In recent years a huge number of studies have been published aiming to find new therapeutic strategies for the treatment of ED.
The NO-cGMP pathway plays a critical role in corpora cavernosa (CC) smooth muscle relaxation and penile erection. A remedy for ED would be to preserve or strengthen the activity of the NO-cGMP pathway. This is already indicated by the success of PDE-5 inhibitors, which inhibit the breakdown of intracellular cGMP.
One such strategy is to enhance serum L-arginine concentration, which is a substrate for NO (nitric oxide – what Hugh Jackman utilises to become wolverine) synthases. However, the level of efficacy reached by the use of chronic L-arginine monotherapy remains uncertain. Recently, L-arginine aspartate-adenosine monophosphate (AMP) combination therapy was shown to be effective for patients experiencing mild to moderate ED. This being so, L-arginine especially in combination with other pro-erectile agents could be useful in the treatment of ED.
It is important to note that oral L-arginine supplementation does not significantly increase L-arginine blood levels because of the hepatic first pass effect or metabolisation by intestinal bacteria. Therefore, L-citrulline (which converts to L-arginine in the kidneys) supplementation might be more effective than L-arginine supplementation since it is neither affected by the hepatic first pass effect nor metabolised by intestinal bacteria. In fact, L-citrulline, in isolation, has been shown effective in improving erectile dysfunction.
Numerous micronutrients and polyphenols found in soy, green tea, and several fruits and vegetables have been described to impact conditions such as ED. An appreciable finding is that long term consumption of quality organic red wine apparently confers some protection against the most frequent form of ED, vasculogenic erectile dysfunction (VED). One of the polyphenols present in red wine is resveratrol. Resveratrol is reported to strengthen penile erection by increasing cGMP and improving endothelial function. A recent publication demonstrated the beneficial effects of resveratrol in diabetes-induced ED and demonstrated that this polyphenol also suppresses apoptosis and oxidative stress, two factors likely involved in VED.
The main herbal agents used to treat ED have been yohimbine, ginseng and Ginkgo Biloba.
Human trials have shown Yohimbine to increase libido, however, results at this time have failed to reach valid conclusions. This being so, future research is strongly recommended. Moreover, it appears that yohimbine does not interact poorly when combined with nitrates (L-arginine, a case in point), unlike treatment with PDE-5 inhibitors.
Korean Red Ginseng:
Recently, a small, randomised, well-designed study of 45 patients showed that Korean red ginseng might be effective in treating ED; however, the study was unable to draw sufficient conclusions to recommend its use. Furthermore, no comparison was made to show interaction between PDE-5 inhibitors. Nonetheless, additional double-blind studies (utilising the validated questionnaire International Index of Erectile Dysfunction) have indicated that Korean red ginseng at a dose of 1 gram 3 times daily, improved erectile dysfunction compared to placebo.
Ginkgo Biloba is the most traded product for ED. However, it has been studied primarily in ED induced by antidepressant medication. Although, “good” results were obtained in initial studies it is important to note that the studies undertaken did not include a placebo group, and the dosages used in the study were highly variable, which makes drawing conclusions difficult. Interestingly, in more recent comprehensive studies no significant benefit has been shown.
Recently Maca powder has become very popular. Randomised double blind studies have indicated, with a small number of patients, improved libido, and a mild improvement in erectile dysfunction.
The human methylene tetrahydrofolate reductase (MTHFR) gene is localised in the short arm of chromosome 1. It is a key enzyme in folic acid metabolism and crucial for homocysteine remethylation to methionine. Two common polymorphisms of MTHFR gene in humans are C677T and A1298C. Interesting recent research has shown that MTHFR C677T polymorphism is associated with risk of developing early onset VED. In fact, it has been found that a high frequency of homozygosity for the 677T genotype of MTHFR in individuals who develop premature VED (<40 years of age). Furthermore, Individuals with 677T genotype had a 3-fold increased risk to develop early onset VED. If you have any questions relating to this post please make contact: A: Mark Hinchey Naturopathy, 601 Glebe Road Adamstown, New South Wales, Australia, 2289 P: 0432234822 (for all appointments) E: firstname.lastname@example.org