Nitric oxide is made internally from L-arginine, which is an amino acid found in red meat, poultry, fish, and dairy products. In other words, L-arginine is the building block for nitric oxide, which is essential for erections. A lack of one can lead to a lack of the other. However, there’s a problem when it comes to treating L-arginine deficiency with supplements.
Animal testicles: derived from bulls and wild boars, the orchic substance has been used as a way to possibly increase testosterone levels and sperm counts. In Singapore, testis soap was once very popular (Figure 2). It is still sold in parts of China and Japan. The dried Dog testis and penis (canis familiaris) is believed to tonify the kidneys and strengthen the yang II. Kidney deficiency is believed to be the cause of impotency in Chinese literature.

Yohimbine. This chemical is found in the bark of an African tree called yohimbe. It has been used as a male aphrodisiac in Africa, and under medical supervision it has been used as a prescription drug to treat ED. Supplements made from yohimbe bark are also available without a prescription, but they can be life-threatening if used at high doses, according to the Natural Medicines Comprehensive Database. The supplement can interact in a harmful way with certain drugs, such as blood pressure medications, and should be avoided by anyone with liver, kidney, heart, or diabetes problems or problems with anxiety or depression. Like DHEA, yohimbine should not be taken without a doctor's supervision.
While these side effects mainly create discomfort, some individuals are at risk for more serious, even life-threatening reactions to these drugs. Some men have reported fainting after taking impotence medications, and priapism (a painful condition involving an erection that does not subside after more than four hours) has also occurred as an effect of impotence drugs. This condition can lead to permanent nerve damage; injectable drugs may also cause irreversible damage to the penis if used incorrectly.

If you’ve been to the health food store lately, you’ve seen shelves lined with vitamins and “organic” supplements, each claiming to boost immunity, revitalize organ function, or “promote health.” And it’s working. Supplements are currently a $30 billion industry in the US, with more than 90,000 products on the market, and vitamin use is on the rise. In fact, a recent survey in Journal of American Medicine Association showed that “52% of US adults reported use of at least 1 supplement product.”
Dr. Niket Sonpal is the Associate Program Director of the Internal Medicine Residency at Brookdale Hospital Medical Center in Brooklyn and an Associate Professor at Touro College of Osteopathic Medicine. He’s a practicing Gastroenterologist and Hepatologist with a focus on Men’s and Women’s Health, and a regular contributor to Women’s health, Shape and Prevention Magazine.
Yohimbine is the principal alkaloid of the bark of the West African evergreen P johimbe (formerly known as C johimbe), family Rubiaceae. The main active chemical present in P johimbe bark is yohimbine hydrochloride (an indole alkaloid), which has stimulant and aphrodisiac effects. However, the levels of yohimbine that are present in P johimbe bark extract are variable and often very low. Therefore, although P johimbe bark has traditionally been used to treat ED [38], there is insufficient scientific evidence to form a definitive conclusion in this area. It is an antagonist of α2-receptors and has no direct relation to erection. It acts as a sex motivation stimulant. Yohimbine has been used as both an over-the-counter dietary supplement in the form of an herbal extract, and as a prescription medicine in purified form for the treatment of sexual dysfunction. Yohimbine 20 mg or adjusted dose has been found to be effective in the treatment of orgasmic dysfunction. Yohimbine was recently associated as a treatment for type 2 diabetes mellitus in animal and human models carrying polymorphisms of the alpha-2A adrenergic receptor gene [39]. The National Institutes of Health states that yohimbine hydrochloride is the standardized form of yohimbine that is available as a prescription medicine in the United States, and has been shown in human studies to be effective in the treatment of male impotence. Yohimbine hydrochloride USP has been used to treat ED. Controlled studies suggest that it is not always an effective treatment for impotence, and evidence of increased sex drive (libido) is anecdotal only. It cannot be excluded that orally administered yohimbine can have a beneficial effect in some patients with ED. The conflicting results available may be attributed to differences in drug design, patient selection and definition of positive response. Yohimbine has been shown to be effective in the reversal of sexual satiety and exhaustion in male rats, and has also been shown to increase the volume of ejaculated semen in dogs, with the effect lasting at least 5 h after administration. Yohimbine has also been shown to be effective in the treatment of orgasmic dysfunction in men, and has also been used for the treatment of sexual side effects caused by some antidepressants, and female hyposexual disorder. Yohimbine has significant side effects, such as anxiety reactions. Higher doses of oral yohimbine may create numerous side effects, such as rapid heart rate, high blood pressure, overstimulation, insomnia and/or sleeplessness. More serious adverse effects may include seizures and renal failure. Yohimbine should not be consumed by individuals with liver, kidney or heart disease, or psychological disorders. The therapeutic index of yohimbine is low; the range between an effective dose and a dangerous dose is very narrow. Side effects include gastrointestinal upset, increased blood pressure, headache, agitation, rash, tachycardia and frequent urination [40].
Tribulus Terrestris is the fruit of the Zygophyllaceae plant and it grows primarily in North China. It is a well-known aphrodisiac with records that trace back to ancient times. There are plenty of animal experiments that verify the effectiveness of Tribulus for improving erectile function. These effects are mostly due to its androgen enhancing ability, namely increasing testosterone levels. Though testosterone doesn’t directly cause an erection, it does play a role. Erection is made possible by many factors, but mostly it's through receptors on cells lining our arteries that stimulate a chain reaction that relaxes the blood vessels that go to the penis, allowing blood flow to get in. Low testosterone is often associated with overall poor metabolic and cardiovascular health. When the test is low, estrogen is usually high, leading to oxidative stress and calcification of the arteries, including the penis, restricting blood flow to the penis. So, improving testosterone levels, and improving overall metabolic function, while reducing oxidative stress is a good plan for improving overall sexual function and erection.

Most importantly, herbal supplements are not well regulated in the United States.  Studies have shown that 40-50% of herbal supplements do not even contain the supposed main ingredient, and many contain substances that are not listed which may have dangerous side effects2.  Another study found that over two thirds of the products tested had substituted other plant species for the plants listed on the label, and a third of products also contained other fillers or contaminants3.  A study by the New York State Attorney General of herbal products sold at GNC, Target, Walgreens, and Walmart found that four out of every five products didn’t contain the ingredient they claimed!  Fourteen US states and territories have petitioned Congress to regulate the herbal supplements industry.


Currently, there are four orally active drugs are available to treat ED. These include: sildenafil citrate (Viagra [Pfizer, USA]), vardenafil hydrochloride (Levitra [Bayer, Germany]), tadalafil (Cialis [Eli Lilly, USA]) and avanafil (Stendra, Spedra [Vivus Inc, USA]). These drugs inhibit the enzyme phosphodiesterase type 5 (PDE-5), which is responsible for the hydrolysis of cGMP. PDE-5 inhibitors and cGMP act as effectors of dilation of smooth muscle of cavernosal bodies. PDE-5 inhibitors are contraindicated in patients taking any kind of nitrate therapy for angina, and may not be appropriate for men with certain health conditions, such as severe heart disease, heart failure, history of stroke or heart attack, uncontrolled high blood pressure or diabetes, and patients with pigmental retinopathy. PDE-5 inhibitors are less effective in men with diabetes and men who have been treated for prostate cancer. PDE-5 inhibitors are also not effective in men with retinitis pigmentosa, a genetic disease involving PDE-5 deficiency. The common side effects of PDE-5 inhibitors include gastrointestinal upset, headache, nasal congestion, back pain and dizziness. The PDE-5 inhibitors may interact with other medications including antihypertension drugs. Nonetheless, the PDE-5 inhibitors are generally safe and effective for most men. The primary mechanism of action of these drugs is through the mediation of NO. NO is one of the key molecules involved in ED. It is a short-lived, highly permeable, pleiotropic, gaseous molecule, secreted from the postganglionic cavernosal parasympathetic nerves, endothelium of the cavernosal blood vessels, platelets in the cavernosal sinuses and phagocytic cells (monocytes, macrophages and neutrophils). NO acts on platelets to inhibit platelets adhesion and aggregation. NO causes relaxation of the smooth muscle of the cavernosal blood vessels of the penis, leading to vasodilation, tumescence and stimulation. Release of NO in the corpus cavernosum of the penis during stimulation activates the enzyme guanylate cyclase, which results in increased levels of cGMP, producing smooth muscle relaxation in the corpus cavernosum and resulting in increased blood flow (5). NO is mainly produced from cavernosal nerves, which are nonadrenergic, noncholinergic nerves within the penis, and acting via its second messenger cGMP. It has been suggested that maintaining normal body weight and mild exercise, as well as dietary supplementation of folic acid, zinc, calcium, vitamin C, vitamin E and L-arginine, a precursor of NO, can support the biochemical pathway leading to NO release [6]. NO is an effector molecule that is involved in a number of intracellular functions such as vasorelaxation, endothelial regeneration, inhibition of leukocyte chemotaxis and platelet adhesion [7]. A small proportion of autonomic nerves do not release either Ach or norepinephrine [8]. For example, the cavernous nerves predominantly release NO in the penis. The exact mechanism is not known, but it is believed to be through increased intracellular calcium. Another gaseous molecule produced in the corpora cavernosa is hydrogen sulphide (H2S), which is also known to be involved in erectile function [9]. H2S activates ATP-sensitive potassium channels in smooth muscle cells. Some reports indicate that NO acts in large vessels and H2S in small vessels. A high level of tumour necrosis factor-alpha has been shown in ED patients [10]. Although current ED therapies using PDE-5 inhibitors are safe and effective, approximately 40% of ED patients do not respond to currently available treatment [11,12]. For these patients, herbal therapy may be useful.
Yohimbe	A number of clinical trials have shown that the primary component of this bark from an African tree can improve sexual dysfunction associated with selective-serotonin reuptake inhibitors (SSRIs) used to treat depression.	This herb has been linked to a number of side effects, including increased blood pressure, fast or irregular heartbeat, and anxiety. Yohimbe shouldn't be used without a doctor's supervision.
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