I spend a lot of time in the gym as a fitness coach and constantly hear conversations about the best way to increase testosterone.
L-arginine is brought up more and more in these chats as an effective testosterone booster.
I decided to take a deep dive into this compound, so I talked to our resident medical professional and my colleagues and read a ton of online materials. After a few weeks of research, I compiled it all here so you and my clients can make an informed decision on l-arginine supplementation.
- L-arginine is produced by the body and is found in foods like red meat, fish, and whole grains, and there are some animal studies indicating its role in testosterone production.
- L-arginine converts to nitric oxide, which regulates blood flow.
- L-arginine can treat many cardiovascular conditions and erectile dysfunction.
What Is L-Arginine and Does It Affect Testosterone?
L-arginine is a semi-essential amino acid that helps build protein and acts as a vasodilator (opening blood vessels), but there isn’t much that points to l-arginine having a direct role in boosting testosterone.
However, we need to take a closer look.
L-arginine is considered semi-essential because the body produces some, and you also need to source through your diet in foods like red meat, fish, whole grains, dairy, and nuts.
L-arginine supplementation is most commonly taken orally or topically and is readily available over the counter.
Another form of l-arginine is administered intravenously by your healthcare provider.
Amino acids, like l-arginine, have essential roles in the body in producing proteins, and we know proteins are critical for many body functions, including muscle gain and recovery.
Studies on animal models related to l-arginine’s impact on increasing testosterone levels show promise, but no human research has garnered the same results 
L-arginine also stimulates the release of growth hormone (human growth hormone) and IGF-1 (another key growth factor) in the body, and additional studies support its vital role in muscle tissue .
As these studies suggest, stimulating growth hormone release enhances muscle recovery, aids muscle growth, boosts metabolism, and decreases fat.
Why Do Bodybuilders Take L-Arginine?
Bodybuilders take l-arginine because it seems to contribute to muscle gain, promote growth hormone release, and encourage fat metabolism, three processes critical to obtaining a well-toned, muscular physique.
L-arginine's role as a vasodilator through conversion to nitric oxide enhances endurance and muscle recovery by promoting blood flow and increasing oxygen and nutrient flow in the muscle. The blood flow can also be increased by using these supplements for vascularity.
This allows a bodybuilder to achieve high intensity during workouts at peak performance with reduced muscle damage 
Effectiveness and Other Uses
L-arginine converts to nitric oxide in the body, regulating blood flow and potentially treats cardiovascular conditions like chest pain or pressure (angina), high blood pressure (hypertension), and heart failure, as well as migraines and erectile dysfunction .
L-arginine supplementation studies show its effectiveness in enhanced athletic performance, both anaerobically and aerobically .
These studies seem to underscore the importance of l-arginine’s role in enhancing protein synthesis and muscle recovery and its importance as a precursor to nitric oxide, which may improve muscle power.
L-arginine may effectively combat fatigue and boost the immune system, which are two significant benefits to athletic performance and everyday life .
From all the stress that bodybuilding causes, including mental and physical, the chances of infections and muscle damage are increased, so it is important to make sure your immune system is up to par.”
- Gareth Gray, M.S., Sports and Exercise Nutrition
A common theme in my online research is that l-arginine supplementation is generally considered safe.
As with any medication or supplement, there is a chance for side effects and interactions, so it is always important to speak with your healthcare provider before starting any supplement.
Potential l-arginine side effects include nausea, abdominal pain, diarrhea, bloating, gout, headache, and airway inflammation .
Because l-arginine is a vasodilator, interactions with medications are used to lower blood pressure because of an increased risk of blood pressure dropping too low. This same risk is present for nitrates and drugs that treat erectile dysfunction .
Individuals should note particular caution for asthmatic individuals because of the potential risk of airway inflammation resulting in worsening asthma symptoms.
Does L-Arginine Work Like Viagra?
L-arginine might work like Viagra by relaxing blood vessels which improves blood flow to the genitals, potentially improving erectile dysfunction. A cautionary note, using l-arginine in conjunction with ED medications like Viagra may cause blood pressure to drop too low.
Does L-Arginine Increase Athletic Performance?
L-arginine can increase athletic performance because it converts to nitric oxide (NO), which in turn regulates blood flow. Increased blood flow translates to increased oxygen to your muscles, resulting in less fatigue and enhanced athletic performance.
So, Should You Take L-Arginine To Increase Testosterone?
While there is no arguing that l-arginine proves to be successful in increasing blood flow resulting in more oxygen to the muscles and enhancing athletic performance, I don’t see much that supports an increase in testosterone levels.
When my clients come to me wishing to boost their testosterone naturally and reap the benefits like better libido, muscle gains, and improved mood and cognitive ability, I usually advise them to take some of the natural testosterone boosting supplements for men that we tried and tested ourselves.
Some of them even include l-arginine in their formula for its vasodilating benefits and better delivery of testosterone to all tissues that need it.
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