Over the past 10 years or so, l-arginine has been one of the most popular muscle building supplement ingredients out there.

It is the primary compound found in most pre-workout “nitric oxide boosters”, with the main forms being l-arginine AKG, l-arginine HCl and regular l-arginine.

The idea is that since l-arginine is a precursor to nitric oxide, and since nitric oxide is a powerful vasodilator (meaning it widens the blood vessels), l-arginine supplementation will increase bloodflow to the working muscles for improved power, endurance and recovery.

But beyond the hyped up marketing and anecdotal reports, what does the actual science say about l-arginine supplementation? Are there any real l-arginine benefits for bodybuilders?

Bodybuilding Supplementation: L-Arginine Benefits?

A common theme in the supplement industry is to simply take an ingredient that has a specific benefit in the body, and then follow the logic that “if some is good, more is better”.

Such is the case with l-arginine.

Yes, l-arginine is indeed an important substance in the human body and it does play a central role in N0 production.

However, not a single shred of scientific evidence exists showing that additional l-arginine supplementation boosts nitric oxide levels in otherwise healthy trainees.

Here’s the simple reason why…

In order for the nitric oxide pathway to function, you need both the enzyme (in this case, an enzyme called “endothelial nitric oxide synthase”, or eNOS for short) as well as the substrate (l-arginine). The reaction between the two produces nitric oxide.

In healthy individuals, the amount of l-arginine in the bloodstream already handily exceeds the amount of eNOS.

In other words, the eNOS enzyme is already completely saturated with l-arginine, and l-arginine is not the limiting factor in nitric oxide production.

Because of this, supplementing with 5 or 10 grams of extra l-arginine is not going to make a damn bit of difference when it comes to nitric oxide production, since your body is already producing enough on its own to max out the effects.

For those with specific clinical conditions (such as heart disease or diabetes) there may be supplemental l-arginine benefits, but this only applies to an extremely small minority of people.

Why then do supplement companies continue to include l-arginine in their formulas?

A few possible reasons…

1) They really don’t give a crap about your results.

For many companies, it’s all about their bottom line and NOT about your goal of building muscle and burning fat. All they want to do is take your money in any way they can.

2) They don’t know any better.

Many of the people formulating these products simply have a poor understanding of basic supplement science.

They don’t bother reading the actual research; they just take ingredients that “sound good” and toss them together.

3) It’s dirt cheap and can be hidden behind other ingredients.

L-arginine is one of the cheapest ingredients out there and is an easy way to hype up a product and beef up the nutrition label. This is why you’ll often see l-arginine listed as the primary ingredient in many formulas.

Most customers won’t know any better, and it allows the company to produce the formula very inexpensively.

Hide it behind a couple ingredients that DO work very well (like creatine and beta alanine) and for dishonest companies, including l-arginine is a no-brainer.

L-Arginine Benefits: The Bottom Line

For an otherwise healthy bodybuilding trainee, there is absolutely no reason to supplement with additional l-arginine.

Your body already produces plenty of it, and the research has never demonstrated any supplemental l-arginine benefits on strength, endurance or muscle growth.

And to be honest, if you see l-arginine listed on the label of ANY bodybuilding supplement, it should raise a massive red flag.

It either means that the company selling it doesn’t give a rat’s ass about your results, doesn’t know any better, or a combination of the two.

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