A deficiency of L-arginine, however, does not generally disrupt nitric oxide synthesis because L-arginine availability is not the rate-limiting step in this process. In fact, research over the past five years has identified an endogenous (occurs in the body naturally) inhibitor called “asymmetric dimethylarginine” or ADMA, an amino acid which blocks the production of nitric oxide. By acting as an L-arginine mimic, this damaging look-alike effectively elbows out L-arginine and pushes it off to the side in the biochemical pathway leading to the synthesis of nitric oxide. ADMA is relatively elevated in patients with hypertension, high levels of cholesterol, triglycerides, homocysteine and low-density lipoprotein (LDL), and low levels of high-density lipoprotein (HDL), as well as with aging itself. This inhibitor of nitric oxide synthesis may very well be the common factor shared by all of these abnormal conditions. Increased levels of this detrimental inhibitor (ADMA) block nitric oxide production, leading to endothelial dysfunction.
The causes of ED are numerous but generally fall into two categories: organic or psychogenic. The organic causes can be subdivied into five categories: vascular, traumatic/postsurgical, neurological, endocrine-induced, and drug-induced. Examples of the psychogenic causes are depression, performance anxiety, and relationship problems. In people with diabetes, the main risk factors are neuropathy, vascular insufficiency, poor glycemic control, hypertension, low testosterone levels, and possibly a history of smoking.
Until recently, erectile dysfunction (ED) was one of the most neglected complications of diabetes. In the past, physicians and patients were led to believe that declining sexual function was an inevitable consequence of advancing age or was brought on by emotional problems. This misconception, combined with men’s natural reluctance to discuss their sexual problems and physicians’ inexperience and unease with sexual issues, resulted in failure to directly address this problem with the majority of patients experiencing it.
L-arginine, an amino acid that is naturally present in the body and helps make nitric oxide, supports a successful erection. Nitric oxide is responsible for making the blood vessels relax, which helps sustain an erection for men. A 1999 study, observed the effects of six weeks of high-dose (5 grams/day) orally administered nitric oxide (NO) donor L-arginine on men with organic ED. Thirty-one percent of those who took 5 grams/day of L-arginine experienced significant improvements in sexual function. Burns told Medical Daily, “l-arginine and deer antler velvet” have been the most popular go-to natural treatments for men.
4. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Erectile dysfunction (updated Nov 2015). https://www.niddk.nih.gov/health-information/health-topics/urologic-disease/erectile-dysfunction/Pages/facts.aspx (accessed Nov 2016). myDr myDr provides comprehensive Australian health and medical information, images and tools covering symptoms, diseases, tests, medicines and treatments, and nutrition and fitness.Related ArticlesImpotence causesFind out the physical and psychological causes of impotence, also called erectile dysfunction or ED.Erectile dysfunction: visiting your doctorFind out what questions a doctor may ask when discussing erectile dysfunction (ED, or impotence8 Surprising causes of erectile dysfunctionOccasional erectile dysfunction is not uncommon, but if it's persistent, erectile dysfunction caAdvertisement
The pathophysiological basis for the predictive ability of ED has been discussed above. It should be emphasized, however, that ED should not only be viewed as a manifestation of obstructive CAD that could be identified by ischaemia revealing tests. Owing to the inflammatory and pro-thrombotic activation of the disease,13 it should also be regarded as an early warning sign of an imminent acute event (mainly acute myocardial infarction)22 due to the rupture of a subclinical plaque, and thus identification of the risk should ideally include plaque vulnerability tests. Finally, an issue that has important clinical implications is by how long the clinical manifestation of ED precedes the clinical manifestation of CAD. According to studies, men with ED and no cardiac symptoms have an increased incidence of experiencing a cardiac event, both acute and chronic, in the ensuing 2–5 years, thus providing a ‘window of opportunity’ for risk reduction management in these patients.2
Combination therapy has proven effective for some men who don’t respond adequately to oral medicines. The idea is to use two drugs with different mechanisms of action for better results. Commonly, sildenafil is used in combination with pellets of alprostadil (synthetic prostaglandin E1) that are inserted into the urethra (the tube in the penis that carries urine from the bladder to the outside of the body). Alprostadil also increases the blood supply to the penis, but by different means.
Erectile dysfunction is frequent in patients with established CAD with prevalence rates ranging between 47 and 75% in studies.2,4,14 The AssoCiatiOn Between eRectile dysfunction and coronary Artery disease (COBRA) trial tested the hypothesis that the ED rate differs in CAD patients according to the clinical presentation (acute vs. chronic coronary syndromes) and the extent of vessel involvement (one vs. two to three vessel disease)15 (Figure 3). The overall ED prevalence in CAD patients was 47%, whereas in the normal coronary angiography group the ED rate was 24%. When separately considered, the ED rate was 22% in patients with acute coronary syndromes (ACS) and one-vessel disease and 55 and 65% in patients with ACS and multi-vessel disease and with chronic coronary syndrome, respectively. The study also showed that both severity (IIEF <10) and duration (>24 months) of ED were predictive of severe coronary involvement at angiography. This study offers pathophysiological and mechanistic explanations related to the clinical setting. In patients with multi-vessel disease, regardless of the clinical presentation, the advanced coronary and systemic atherosclerosis is the reason for the high rate of ED. However, in the setting of acute myocardial infarction with one-vessel disease, ED is far less frequent because the atherosclerotic burden is modest (i.e. abrupt occlusion of a single non-obstructing plaque in the absence of extensive atherosclerosis) in both the coronary and penile circulations.15,16
Normal penile erection is controlled by two mechanisms: reflex erection and psychogenic erection. Reflex erection occurs by directly touching the shaft of the penis, while psychogenic erection occurs by erotic or emotional stimuli. ED is a condition where erection does not take place by either mechanism. ED can occur because of hormonal imbalance, neural disorders or lack of adequate blood supply to the penis.54 Lack of blood supply can be a result of impaired endothelial function associated with CAD.54
A collection of risk factors that strongly predict heart disease—termed the metabolic syndrome—is also associated with erectile dysfunction. An increasingly prevalent condition, this syndrome includes low HDL, increased triglycerides, high blood sugar, and heightened inflammation and causes a three-fold or greater risk of heart attack, stroke, and diabetes. It is largely attributable to excess weight, poor diet, and inactivity and afflicts at least 47 million Americans, signaling that an epidemic of erectile dysfunction is sure to follow. Indeed, a survey of 2,400 men participating in a health screening revealed that metabolic syndrome increases the likelihood of erectile dysfunction by 48%.10
A considerable number of patients with ED can have psychogenic factors as the only cause, or in combination with organic causes of ED. Depression, low self-esteem and social stresses are among the psychogenic factors that can lead to ED. Depression is an independent risk factor for both ED and IHD; these three disease conditions are interlinked.51 Psychogenic ED can be managed by multiple psychological interventions such as cognitive behavioural therapy, couples counselling and guided sexual stimulation techniques.52
Branded Viagra can now be bought over the counter in pharmacies, but please check with your GP first if you have a medical condition. It's important to use a reputable pharmacy, as there is a large market in counterfeit drugs for erectile dysfunction, especially over the internet. These contain varying amounts of the active ingredient and sometimes completely different drugs.
Joel Fuhrman, M.D. is a board-certified family physician, six-time New York Times bestselling author and internationally recognized expert on nutrition and natural healing, who specializes in preventing and reversing disease through nutritional methods. Dr. Fuhrman coined the term “Nutritarian” to describe his longevity-promoting, nutrient dense, plant-rich eating style.
Treatment of ED which was previously confined to invasive procedures, cavernosal injections or to rather ineffective oral medications was revolutionized in 1999 with the introduction of the orally administered PDE5 inhibitor sildenafil. Phosphodiesterase type 5 inhibitors are the first-line therapy for ED of organic aetiology unless there is a specific contraindication to their use. This class of agents is widely used because of its effectiveness and safety.38 Interactions with cardiovascular drugs have been minimal with the exception of nitrates and other nitric oxide (NO) donors (such as nicorandil), where co-administration may result in severe vasodilation and hypotension. However, nitrates are often overused in clinical practice; therefore, the option of their discontinuation should be considered. A strong body of clinical data shows that all three agents (sildenafil, tadalafil, and vardenafil) do not increase the risk of non-fatal myocardial infarction, stroke, or cardiovascular deaths. These drugs do not exacerbate ischaemia or worsen exercise tolerance in patients with known CAD who achieve levels of exercise comparable or greater than that achieved during sexual intercourse.38,39 Phosphodiesterase type 5 is expressed throughout the human body, including the pulmonary and systemic vasculature and hypertrophied myocardium. While currently their only additional indication, beyond ED, is idiopathic pulmonary hypertension (for sildenafil and tadalafil), they show potential to be of benefit in several other conditions, such as CAD and systolic heart failure.39 Mechanisms of benefit of PDE5 inhibitors include pulmonary and systemic vasodilation, increased myocardial contractility, reduced large artery stiffness and wave reflections, improved endothelial function, and reduced apoptosis, fibrosis and hypertrophy through mechanisms involving NO, cyclic guanosine monophosphate, protein kinase G and Rho kinase.39 A very important issue is whether treatment of ED per se (and not of its risk factors and comorbidities) will have an impact on cardiovascular risk. While this applies to all therapeutic modalities of ED, it is particularly pertinent for PDE5 inhibitors, since they represent the mainstay of ED therapy. Data are limited to date. Gazzaruso et al.21 showed a trend of PDE5 inhibitors to reduce cardiovascular morbidity and mortality in diabetic patients with silent CAD and ED, while Frantzen et al.40 showed that 2 years after the introduction of sildenafil, the relative risk of the incidence of CVD among men with ED compared with healthy men significantly decreased from 1.7 to 1.1.
Following the breakthrough in ED treatment using PDE5-inhibitors, Western medicine has now moved on to a new frontier of regenerative medicine, with stem cell and gene therapy leading the way (25). There is a practical need for novel therapy as a significant portion of diabetic or post-prostatectomy ED patients do not respond to oral pharmacotherapy. To date, stem cells derived from different sites including adipose tissue-derived stem cells, bone marrow mesenchymal stem cells and muscle-derived stem cells have been investigated using animal models for ED, to study their effects on neural, vascular, endothelial or smooth muscle regeneration (25,26).
For oral erectile dysfunction medicines to work as desired, they must be used properly in the first place. This means taking the medicine 30–45 minutes before engaging in sexual intimacy; taking the drug on an empty stomach or at least avoiding a heavy or high-fat meal before taking the drug (this is especially important when using sildenafil); and engaging in adequate genital stimulation before attempting intercourse. Drinking small amounts of alcohol (one to two drinks) should not compromise the effectiveness of erectile dysfunction medicines, but larger amounts of alcohol can diminish a man’s ability to have an erection.