Overview and Risk Factors
Erectile dysfunction (ED) is the inability to acquire or sustain an erection of sufficient rigidity for sexual intercourse. The condition affects 15 million to 30 million men in the United States. Most cases of ED consist of impotence, the inability to achieve or sustain an erection during attempted sexual intercourse more than 75% of the time. Other disorders include abnormal curvature of the penis during erection (Peyronie's disease), priapism, decreased libido, inability to ejaculate, and premature ejaculation. Any disorder that impairs blood flow to the penis (eg, atherosclerosis) or causes injury to the penile nerves, smooth muscle, or fibrous tissue has the potential to cause ED. At least 25% of cases are related to reversible etiologies, including psychogenic causes, endocrine abnormalities, and drugs (eg, sympathetic blockers, antidepressants, and antihypertensives).
Changes in erectile function are common and normal with age. Erections may take longer to develop, be less rigid, or require more direct stimulation. Orgasms may be less intense, the volume of ejaculate decreases, and the refractory period increases. Further, emotional disturbances may result in erectile difficulties in the absence of organic pathology. However, ED is not an inevitable consequence of aging. Most cases are treatable, and occasional episodes are considered normal.
Risk Factors
Age. Erectile dysfunction is most common in men older than 65. About 5% of 40–year–old men and 15% to 25% of 65–year–old men experience some degree of erectile dysfunction.
Vascular disease. Atherosclerosis causes a reduction in blood flow and accounts for 50% to 60% of cases.
Diabetes mellitus. At least half of patients with long–standing diabetes experience ED, due to damage of small blood vessels and nerves.
Neurologic conditions. Several neurologic conditions result in ED, including spinal cord and brain injuries, multiple sclerosis, Parkinson's disease, and Alzheimer's disease.
Hormone imbalance. Testosterone deficiency (eg, pituitary tumor, and kidney or liver disease) can result in loss of libido and erectile difficulties.
Surgery. Colon, prostate, bladder, and rectum surgery may damage nerves and blood vessels involved in erection. Nerve–sparing techniques decrease impotence incidence to around 50%.
Radiation therapy. Radiation treatment for prostate or bladder cancer may cause ED.
Medications. More than 200 commonly prescribed drugs result in ED as a prominent side effect. These include beta–blockers, thiazides, antihistamines, antidepressants, tranquilizers, and appetite suppressants.
Substance abuse. Excessive use of alcohol, tobacco, marijuana, 3,4–methylenedioxymethamphetamine (MDMA, better–known as Ecstasy), and other recreational drugs can cause ED, which may be irreversible in some cases. For example, excessive tobacco use can permanently damage penile arteries.
Obesity. Excess body fat weight contributes to ED by increasing estrogen activity and aggravating diabetes and lipid disorders.
Diagnosis and Treatment
Diagnosis
A careful medical and sexual history is essential for diagnosis. Sexual history should include onset of symptoms, presence of spontaneous erections (ie, morning erections), and risk factors for impotence (eg, cigarette smoking, diabetes mellitus, hypertension, drug abuse, obesity). A psychiatric interview and questionnaire may reveal psychological factors, such as depression and anxiety. In some cases, it may be helpful to interview the patient's sexual partner.
Physical examination can provide clues to systemic problems, such as neurologic abnormalities (eg, visual field defects that occur with pituitary tumor), vascular abnormalities (eg, decreased peripheral pulses), and developmental abnormalities (eg, abnormal secondary sex characteristics, penile curvature, gynecomastia).
Laboratory evaluation may include serum testosterone, prolactin, and thyroid function tests to evaluate for hormonal abnormalities. Nocturnal penile tumescence testing can be used to quantify the number, tumescence, and rigidity of erectile episodes during sleep, which can rule out psychological etiologies and can help identify men who might benefit from corrective vascular surgery. Doppler ultrasound or angiography of the penile arteries may be indicated to identify arterial obstruction or venous leak.
Treatment
Treatment is aimed at restoring the capacity to acquire and sustain penile erections and reactivating the libido.
The most commonly used class of medications is phosphodiesterase-5 inhibitors (eg, sildenafil, vardenafil, tadalafil). These medications are contraindicated in men taking nitrates. Hormonal therapy with testosterone may be effective, but is only recommended in a small number of patients with documented hypogonadism. Yohimbine may improve erections and increase libido by stimulating the parasympathetic nervous system.1
Treatment of comorbid psychiatric disorders may improve sexual functioning. Between 20% and 50% of men with impotence have symptoms of depression, which may contribute to erectile dysfunction. Self-esteem may also suffer as a result of erectile dysfunction. Individual or couples psychotherapy may be a helpful part of impotence treatment.2
Penile injections, intraurethral therapies (eg, alprostadil), and vacuum devices may be beneficial. Surgical interventions may include reconstruction of blocked arteries and implantable prostheses.
Nutritional Considerations
Impotence is often the result of vascular disease. Risk factors for cardiovascular disease are commonly found in patients with erectile dysfunction. These include obesity, elevated cholesterol and triglyceride levels, smoking, inactivity, endothelial dysfunction, elevated C-reactive protein concentration, and metabolic syndrome.3-6 Moreover, impotence should be viewed as a sign that other cardiovascular problems may manifest in the future, and that diet and lifestyle changes to help prevent these problems are essential.
Although the evidence on nutritional treatment is limited, interventions that reduce cardiovascular risk factors or improve blood vessel reactivity (diet, exercise, and certain botanical agents) may improve impotence symptoms. In one study, a low-fat, low-cholesterol diet combined with exercise resulted in normal sexual function in 31% of impotent men, compared with about 5% in a control group. This combination also significantly reduced several vascular risk factors, including obesity, high blood pressure, elevated serum lipids, and elevated blood glucose and insulin concentrations.7 See Coronary Heart Disease chapter for dietary factors to prevent or treat cardiovascular disease.
Dietary supplements are not a substitute for a healthful diet and lifestyle, because they do not address the cause of vascular disorders. Nonetheless, 2 dietary supplements, L-arginine and ginseng, have proven effective in treating erectile dysfunction in clinical trials. These appear to work by enhancing nitric oxide release and increasing cyclic guanosine monophosphate (cGMP), which allows penile arterial relaxation and engorgement.
L-arginine is a precursor to nitric oxide. It was shown to be effective in 30% to 40% of patients taking 3 to 5 grams per day, compared with placebo.8,9 Combinations of arginine and yohimbine hydrochloride10 or arginine and flavonoids that stimulate production of nitric oxide synthase (eg, oligomeric proanthocyanidins) increase the percentage of individuals responding to L-arginine to more than 90%.11 However, not all trials of L-arginine have been adequately controlled, and further study is necessary.
Panax ginseng contains active ingredients (ginsenosides) that increase the release of nitric oxide. Controlled clinical studies have found that mean scores on the International Index of Erectile Function were significantly higher in patients treated with ginseng than in those who received placebo.12 The studies also found that the number of patients treated with ginseng who experienced improvement in erectile parameters was double that of placebo-treated patients.13 Additional controlled clinical studies are needed to definitively establish a role for ginseng in ED treatment.
Dietary supplements should be used only under medical supervision, due to the possibility of medication interactions.
Orders
See Basic Diet Orders chapter and nutritional recommendations in Coronary Heart Disease chapter.
Smoking cessation.
Exercise prescription.
Referral for psychiatric evaluation, as appropriate.
What to Tell the Family
Discussion with family members regarding the patient's medical problems should only be done with permission from the patient, particularly in the case of sensitive diagnoses, such as erectile dysfunction. With the patient's permission, however, the sexual partner may be included in discussions of treatment options.
Patients with impotence are commonly at risk for other cardiovascular problems. A low-fat, vegetarian diet, along with smoking cessation and exercise, can be an effective treatment for these risk factors. To the extent that the entire family adopts such a diet, patient adherence is facilitated, and the patient and family are all likely to benefit.
References
1. Weber R. Erectile Dysfunction. Clinical Evidence. 2003;1003-1011.
2. Althof SE, Wieder M. Psychotherapy for erectile dysfunction: now more relevant than ever. Endocrine. 2004;23:131-134.
3. Fung MM, Bettencourt R, Barrett-Connor E. Heart disease risk factors predict erectile dysfunction 25 years later: the Rancho Bernardo Study. J Am Coll Cardiol. 2004;43:1405-1411.
4. Giugliano F, Esposito K, Di Palo C, et al. Erectile dysfunction associates with endothelial dysfunction and raised proinflammatory cytokine levels in obese men. J Endocrinol Invest. 2004;27:665-669.
5. Gunduz MI, Gumus BH, Sekuri C. Relationship between metabolic syndrome and erectile dysfunction. Asian J Androl. 2004;6:355-358.
6. Bacon CG, Mittleman MA, Kawachi I, et al. Sexual function in men older than 50 years of age: results from the health professionals follow-up study. Ann Intern Med. 2003;139:161-168.
7. Esposito K, Giugliano F, Di Palo C, et al. Effect of lifestyle changes on erectile dysfunction in obese men: a randomized controlled trial. JAMA. 2004;291:2978-2984.
8. McKay D. Nutrients and botanicals for erectile dysfunction: examining the evidence. Altern Med Rev. 2004;9:4-16.
9. Chen J, Wollman Y, Chernichovsky T, et al. Effect of oral administration of high-dose nitric oxide donor L-arginine in men with organic erectile dysfunction: results of a double-blind, randomized, placebo-controlled study. BJU Int. 1999;83:269-273.
10. Lebret T, Herve JM, Gorny P, Worcel M, Botto H. Efficacy and safety of a novel combination of L-arginine glutamate and yohimbine hydrochloride: a new oral therapy for erectile dysfunction. Eur Urol. 2002;41:608-613.
11. Stanislavov R, Nikolova V. Treatment of erectile dysfunction with pycnogenol and L-arginine. J Sex Marital Ther. 2003;29:207-213.
12. Hong B, Ji YH, Hong JH, et al. A double-blind crossover study evaluating the efficacy of Korean red ginseng in patients with erectile dysfunction: a preliminary report. J Urol. 2002;168:2070-2073.
13. Choi HK, Seong DH, Rha KH. Clinical efficacy of Korean red ginseng for erectile dysfunction. Int J Impot Res. 1995;7:181-186.
