L-arginine benefits get a lot of press in the bodybuilding world as a supplement that can give those looking to build mass and lean out a leg up due to its role in the body’s production of human growth hormone and creatine.

But interestingly, the most well-researched benefit of this naturally-occurring amino acid has nothing to do with what meets the eye.

Rather, L-arginine acts most prominently as a waste remover and vasodilator that has the potential to improve heart function, reduce headaches and enhance sexual health.

What Is L-Arginine?

L-arginine is a semi-essential amino acid (also known as a conditional amino acid). This isn’t to say it’s “semi-essential” the way that having the perfect playlist is semi-essential to a good workout.

To understand the concept, you need to understand the difference between essential and non-essential amino acids.

Your body requires 20 amino acids to perform all it’s necessary functions. You need all of them, there’s no doubt about that.

What separates the nine essential amino acids from the 11 non-essential amino acids is the fact that your body can manufacture the 11 non-essential amino acids itself – it’s not essential that you consume them in your regular diet.

On the flip side, the nine essential amino acids aren’t manufactured by your body, so you must consume them on a daily basis to keep your system functioning at optimum levels.

Technically, arginine is a non-essential amino acid. Your body does, in fact, do a good job of manufacturing it on its own.

However, there are certain instances – specifically during trauma or illness – when your body may not be able to keep up with demand, If this happens, it’s a good idea to add a supplement to your diet to help your body return to optimum levels.

L-Arginine Benefits and Nitric Oxide

Quite possibly L-arginine’s biggest benefit lies in its role as a precursor to nitric oxide. Nitric oxide functions as a vasodilator, essentially “opening up” veins and arteries, making it easier for blood (and all the oxygen and nutrients it carries) to flow freely through your body.

From a broad perspective, this is huge – just think of all the health problems related to the narrowing of blood vessels – heart disease, headaches, erectile dysfunction (ED) – all of which benefit from increases in blood flow.

In fact, there’s been solid research to back up L-arginine supplementation’s benefits to those suffering angina, thrombolysis related to DVT (deep vein thrombosis), and ED.

L-Arginine Benefits and Exercise Performance

It makes logical sense, then, that L-arginine supplementation might also improve exercise performance.

The efficient flow of blood to working muscles during exercise is essential to performance, so conceptually, a supplement that stimulates vasodilation should be able to boost the delivery of nutrients to muscles while buffering away waste products.

There is, in fact, some evidence that this is the case, particularly in individuals who may have experienced narrowing of the veins and arteries.

For instance, a 2002 study published in the Journal of the American College of Cardiology found that those suffering chronic, stable angina saw an improvement in exercise capacity and quality of life when they consumed an arginine-rich medical food as an adjunct to traditional therapy.

Unfortunately, research regarding the benefits of L-arginine on exercise performance are mixed and inconclusive. Whereas one study might indicate an improvement in aerobic capacity, another study indicates no improvement.

These results are further confused by the broad variations in study type, where L-arginine is often provided to study participants in combination with other supplements, such as antioxidants or other amino acids.

It’s hard to know in these instances if results are due to one substance, the other substance, or the combination thereof.

That’s certainly not to say L-arginine doesn’t have the potential to act as an ergogenic aid.

There’s enough research out there to certainly indicate it might. Case in point – a 2005 article published in the Journal of Sports Science and Medicine that found prolonged intake of a combined L-arginine-L-aspartate supplement synergistically reduced blood lactate accumulation and oxygen consumption during submaximal cycling.

In other words, the amino acid supplement made submaximal exercise feel easier and more tolerable.

Likewise, a 2010 article published in the Journal of the International Society of Sports Nutrition found that a combined arginine and antioxidant supplement provided to elderly male cyclists increased the cyclists’ anaerobic threshold, making it possible for them to work harder before experiencing the buildup of lactic acid in working muscles.

The trick is understanding that while the research is certainly interesting, there are no clear guidelines or references pointing to L-arginine’s direct benefits to exercise performance, especially concerning ideal timing or dosage.

Consuming L-arginine in Your Diet

If you’re concerned about your levels of L-arginine, or if you want to try supplementing L-arginine as a potential ergogenic aid, talk to a registered dietician or naturopathic doctor to get recommendations on proper dosage based on your personal needs.

That said, you can also increase your intake of L-arginine through your diet by consuming high-quality proteins rich in the amino acid. Foods including cage-free eggs, grass-fed beef, wild salmon, nuts and seeds are all good sources of L-arginine.