Can L-arginine Cure Erectile Dysfunction And Improve Libido?
By Johnathan P Cumberwell
L-arginine may be effective at helping you overcome erectile dysfunction.
However, it will typically not increase your libido.
L-arginine helps you ‘get it up’ because it increases your production of nitric oxide.
You simply need nitric oxide in order to get erections.
Because this is what opens the blood vessels in your penis, so that blood can flow into your penis and produce an erection.
If you don’t produce enough nitric oxide, you will find it almost impossible to get an erection.
Let’s learn more about L-arginine.
What Is L-arginine?
L-arginine is an amino acid. One of many, because in your body you have more than 500 different amino acids.
Yet there are two basic types of amino acids:
- Essential amino acids, and
- Semi-essential amino acids
Essential amino acids cannot be synthesized in the body, so they have to be obtained via foods (or supplements).
The semi-essential amino acids on the other hand, can be manufactured in your body.
L-arginine is one of the semi-essential amino acid. This means that you normally produce adequate amounts of it.
However, certain people such as infants and people with particular health conditions, do not produce enough. They therefore need to get additional L-arginine either through foods or supplements.
And even though your body in theory should produce enough of it, there are still several reasons why you may not produce enough. Particularly in the blood vessels in your penis.
And this will in turn make it difficult to get erections.
Although there are more than 500 different amino acids, the most well-known are the 22 so-called proteinogenic amino acids.
These are called proteinogenic because they are precursors to, or building blocks of, proteins.
L-arginine, by the way, is also one of these proteinogenic amino acids.
L-arginine Helps You ‘Get It Up’ By Increasing Your Nitric Oxide Production
The smooth muscles in the blood vessels in your penis are normally contracting. When they contract, they squeeze the blood out of these blood vessels.
This in turn causes your penis to be flaccid.
When nitric oxide is diffused into these smooth muscles, something happens.
They start to relax.
And when they relax, they give up the tight squeeze around your blood vessels. Which means that blood is allowed to flow into these blood vessels.
When enough blood enters, your penis gets filled with blood and an erection forms.
That is how you get an erection. And this is why nitric oxide is so important.
Let’s look at what the scientists have to say.
Scientific Studies On L-arginine’s Impact On Libido And Erectile Dysfunction
L-arginine Study 1: June 2020
The goal of this study was to evaluate the effectiveness and tolerability of 5 mg of tadalafil and 2,500 mg of L-Arginine, in monotherapy and combination therapy.
The study included 300 men with erectile dysfunction. The men were put in three groups, and received the following treatment:
- Group 1: L-arginine 2,500 mg
- Group 2: Tadalafil 5 mg
- Group 3: L-arginine 2,500 mg + Tadalafil 5 mg
The men received the treatment daily for 12 weeks.
The ED score for the men in the 3 groups increased as follows:
- Group 1: 15.0 to 18.1
- Group 2: 14.8 to 20.8
- Group 3: 14.9 to 22.0
The group that took the combined treatment had a significantly larger improvement in erectile dysfunction score, than either of the single treatments.
But also the group that only received the L-arginine treatment, saw significant improvements.
L-arginine Study 2: February 2019
The aim of this study was to assess the potential role of arginine supplements on ED as alternatives to phosphodiesterase inhibitors.
This study reviewed existing research studies that had been done on arginine supplements and erectile dysfunction.
In total, 10 randomized controlled trials met the inclusion criteria, involving 540 patients with ED.
The study found that arginine supplements with dosage ranging from 1,500 to 5,000 mg significantly improved ED, compared with placebo or no treatment.
It also reported that arginine supplements caused significant improvements in the ED scores of overall satisfaction, intercourse satisfaction, orgasmic function, and erectile function, whereas the sexual desire score was unchanged.
L-arginine Study 3: March 2013
L-arginine Study 4: February 2011
The aim of this study was to investigate the ergogenic potential of arginine on nitric oxide synthesis, muscle blood flow, and skeletal muscle protein synthesis.
8 healthy young men participated in 2 leg resistance exercises and ingested a drink containing, either 10,000 mg L-arginine, or a placebo. The study lasted one day.
The study found that 10,000 mg of arginine did not increase nitric oxide synthesis or muscle blood flow. Neither did it enhance mixed or myofibrillar skeletal muscle protein synthesis, either at rest or after resistance exercise.
L-arginine Study 5: November 2010
The purpose of this study was to analyze whether dietary supplementation with L-arginine improves exercise efficiency and exercise tolerance in healthy humans.
9 healthy men (from 19-38 years of age) consumed a beverage containing 6 g of L-arginine, or a placebo beverage, and then completed a series of moderate- and severe-intensity exercises, 1 hour later.
In the L-arginine group, nitric oxide concentrations were 104% higher, blood pressure was 6% lower, steady-state oxygen uptake during moderate-intensity exercise was 7% lower, and time to exhaustion was extended by 26%.
L-arginine Study 6: October 2004
The aim of this study was to analyse the effects of L-arginine on endothelial function in patients with atherothrombosis (which is the formation of a blood clot within an artery as a result of atherosclerosis).
The study indicated that acute or chronic administration of supplemental L-arginine enhances endothelial nitric oxide production, and improves endothelial function in the setting of atherothrombosis.
It found that L-arginine does this through:
- Increased intracellular uptake via the high-affinity cationic transporter
- Substrate competition with asymmetric dimethylarginine
- A naturally occurring inhibitor of nitric oxide synthase
- Direct antioxidant activity
- Stimulated release of histamine from mast cells, which produces a vasodilator response
- Decreased activity of norepinephrine, which promotes the effect of endogenous vasodilators including nitric oxide
- Increased insulin secretion, which causes vasodilation
The study also found that L-arginine may have a negative effect on endothelial function, via creatine, but that the net effect of the supplement is positive.
L-arginine Study 7: June 2003
The aim of this study was to investigate the possibility of overcoming erectile dysfunction by increasing the amounts of endogenous nitric oxide with Pycnogenol (pine bark) and L-arginine.
The study included 40 men, aged 25-45 years, without confirmed organic erectile dysfunction. The study lasted for 3 months.
The men were given 1,700 mg of L-arginine per day during the first month.
During the second month, the men were given 1,700 mg of L-arginine + 80 mg of pine bark, per day.
And during the third month, the men were given 1,700 mg of L-arginine + 120 mg of pine bark, per day.
After the first month, 5% experienced normal erections. After the following month, 80% experienced normal erections. And after the third month, 92.5% of the men experienced normal erections.
L-arginine Study 8: December 2002
The goal of this study was to evaluate the nitrate-induced, endothelium-independent vasodilatation from L-arginine in patients with essential hypertension.
35 patients with essential hypertension received either 6,000 mg of L-arginine, or a placebo.
Patients were then examined for flow-mediated endothelium-dependent dilatation of the brachial artery (the major blood vessel of the upper arm), before and 1.5 hour after administration of the L-arginine, or the placebo.
The study concluded that administration of L-arginine acutely improved endothelium-dependent, flow-mediated blood vessel dilatation by more than 300% in these patients.
L-arginine Study 9: June 2002
L-arginine Study 10: December 2001
The purpose of this study was to determine, in a prospective randomized, double-blind placebo-controlled study, the effect of 6 weeks of 5,000 mg/day L-arginine on men with organic erectile dysfunction.
The study included 50 men with confirmed organic ED. They first went through a 2-week placebo run-in period, and then received 5,000 mg/day L-arginine, or a placebo.
Oral administration of L-arginine in high doses seemed to cause significant subjective improvement in sexual function in men with organic ED, but only if they already have decreased nitric oxide excretion or production.
L-arginine Study 11: February 1999
The purpose of this study was to examine the effectiveness and safety of L-arginine, in the treatment of mixed-type impotence.
32 patients with impotence and with a mean age of 51.6 years, enrolled in the study. They were given 1,500 mg per day of L-arginine, or a placebo, for 17 days. Then the groups were switched.
1,500 mg/day of L-arginine is not better than placebo as a first-line treatment for mixed-type ED.
L-arginine Study 12: September 1997
The aim of this study was to determine whether dietary supplementation of L-arginine can stimulate penile erection, and whether ancillary pathways for penile erection may exist.
Adult male (5 months old) and aged (20 months old) rats were fed L-arginine dissolved in tap water, for 8 weeks.
After 8 weeks, the maximal intracavernosal pressure was increased by 21% in the adult group, and 32% in the aged group, compared to the control group.
Also, penile nitric oxide synthase activity was increased by almost 100% in the L-arginine treated groups, vs. the control group.
Is L-citrulline Better Than L-arginine?
The goal of supplementing with L-arginine, is to deliver this L-arginine to the enzyme nitric oxide synthase.
This way, nitric oxide synthase can use this L-arginine to produce nitric oxide. Which you need in order to get erections.
However, supplementing with L-arginine may not be the optimal way to get L-arginine to your nitric oxide synthase.
Because your gut and liver break it down. So that in the end, only a small amount of the L-arginine actually reaches the end destination.
Research has indicated that as much as 38-75% of the L-arginine is lost on the way.
Therefore, you may be better off supplementing with L-citrulline instead.
Because it does not undergo transformations in your gut or liver (or at least to a much smaller extent).
When it reaches your kidneys, it is transformed to L-arginine.
Which means that essentially all the L-citrulline converts to L-arginine, which is then available for nitric oxide production.
This is what you want.
Let’s have a look at what research says about this.
L-citrulline Study 1: June 2019
The aim of this study was to investigate whether oral administration of the amino acids L-arginine and L-citrulline could effectively reduce blood pressure by increasing nitric oxide production.
The study suggested that oral L-arginine supplementation can lower blood pressure by 5.39/2.66 mmHg.
And that oral L-citrulline supplementation can lower blood pressure in the range of 4.1/2.08 to 7.54/3.77 mmHg.
L-citrulline Study 2: April 2017
The purpose of this study was to determine the relative efficiency of arginine and citrulline supplementation to improve arginine availability.
Male mice were adapted to 1 of 7 experimental diets for 2 weeks. The basal diet contained 2,500 mg L-arginine/kg, whereas the supplemented diets contained an additional 2,500, 7,500, and 12,500 mg/kg diet of either L-arginine or L-citrulline.
On the final day, after a 3-hour food deprivation, the mice were continuously infused with a diet similar to the dietary treatment, along with L-arginine, to determine the first-pass metabolism FPM (extent of breakdown) of L-arginine.
Supplemental arginine underwent an ∼70% FPM, indicating that only 30% was available for nitric oxide production.
The study also found that L-citrulline increased arginine concentrations by 35% more than did L-arginine.
L-citrulline Study 3: October 2013
The goal of this study was to investigate whether oral L-citrulline supplementation improves erectile function in rats with acute arteriogenic erectile dysfunction.
Rats were divided into three groups: A control group, a group where ED was provoked, and a group where ED was provoked and the rats received L-citrulline.
The study lasted for 4 weeks.
The rats who received L-citrulline had significantly improved intracavernous pressure / mean arterial pressure, more smooth muscle expression and higher nitric oxide levels, compared to the group who did not receive L-citrulline.
L-citrulline Study 4: April 2012
The goal of this study was to assess nitric oxide production in subjects with MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) and the effect of the nitric oxide precursors arginine and citrulline.
Arginine and, to a greater extent, citrulline supplementation increased the arginine synthesis rate, the plasma concentrations and flux of arginine and citrulline, and nitric oxide production.
The study concluded that citrulline supplementation was superior at increasing nitric oxide production.
L-citrulline Study 5: January 2011
The aim of this study was to test the efficacy and safety of oral L-citrulline supplementation in improving erection hardness in patients with mild erectile dysfunction
The study included 24 men with an average age of 56.5 years, who had mild ED. They were given 1,500 mg of placebo for one month, and then 1,500 mg of L-citrulline for the following month.
50% of the men given L-citrulline reported improvement in erection hardness.
The mean number of intercourses per month also increased 68% for the men given L-citrulline.
L-arginine Study 6: October 2007
The purpose of this study was to assess the metabolic conversion and subsequent pharmacodynamic effects of L-citrulline and L-arginine.
20 healthy volunteers received six different dosing regimes of placebo, citrulline, and arginine.
For 7 days, the participants received either:
- L‐citrulline 750 mg twice daily
- L‐citrulline 1,500 mg twice daily
- L‐citrulline 3,000 mg twice daily
- L-arginine immediate‐release 1,000 mg
- L-arginine sustained‐release 1,600 mg twice daily
Pharmacokinetic parameters were calculated after 1 week of supplementation.
L‐citrulline increased plasma L-arginine concentration and augmented nitric oxide-dependent signalling, more effectively than L-arginine.
Other Potential Health Benefits From L-arginine And L-citrulline
In addition to its potentially beneficial effects on erectile functioning, L-arginine is also used for heart and blood vessel conditions including congestive heart failure, chest pain, high blood pressure, coronary artery disease, blood clots and stroke.
Some people also use L-arginine for preventing the common cold, reducing healing time of injuries, improving athletic performance, boosting the immune system, stimulating the release of growth hormone, increasing bone strength and preventing inflammation.
L-arginine is also reported to improve sperm production and sperm motility.
Let me tell you about my experience taking L-arginine and L-citrulline.
My Experience With L-arginine And L-Citrulline Supplements
To me, this was highly unusual. I mean, I was struggling with erectile dysfunction at the time, and would normally never get spontaneous erections.
I also had a few other episodes with spontaneous erections after taking L-arginine. But it was nothing consistent or predictable.
Hence taking 1.5 grams of L-arginine in the morning did not help me overcome my ED.
I also tried taking 1.5 grams of L-arginine before sex.
I noticed improvements at times, but it was not consistent. Hence, 1.5 grams of L-arginine alone was not able to help me with erectile dysfunction.
Therefore, I increased the dose to what I used for most of the herbal supplements: To 7 grams.
I mixed one tablespoon (not fully topped) of the powder (about 7 grams) with cold water. I stirred until the powder was dissolved, and then drank it. I did this about one hour before sex.
To me, L-arginine has no taste, so taste-wise taking this was pretty much just like drinking water.
And taking 7 grams had a much more profound effect than taking just 1.5 grams. To me, this did produce noticeable results.
This normally made my erections stronger, fuller and longer lasting.
However, now I no longer take L-arginine. I have switched to L-citrulline.
Because it produces even better and more consistent results.
Safety Of L-citrulline And L-arginine
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