L-Citrulline: More Reps, Bigger Pumps, Greater Gains


If you’re reading this article, you’ve probably heard of L-Citrulline.

But do you really know what it is and how it works?  Most people think Citrulline is just a “nitric oxide supplement”, but if you were to explore the research you’d see that it’s actually so much more.

Well, not to worry.  That’s what I’m here for…

I’ve read every just about every published study on Citrulline and, although it’s not as well known as some other supplements, it’s without a doubt one of the most useful and effective.

By the end of this article you’ll know everything you need to know about this wonderfully unique amino acid, including,

  • What It Is
  • The Proven Benefits
  • L-Citrulline Dosing
  • Side Effects
  • Choosing The Best L-Citrulline Supplement

And a whole lot more!

So if you’re ready to learn all about L-Citrulline and how it can potentially benefit you, let’s get started…

What Is L-Citrulline?

L-Citrulline amino acid molecule

L-Citrulline is a non-proteinogenic, non-essential amino acid.

This means it isn’t used to make proteins, and can actually be produced by the body, but make no mistake…

It plays an important part in several critical bodily functions.

Citrulline is a precursor to the amino acid, Arginine, which in turn is used to produce Nitric Oxide.

This has earned Citrulline a reputation as a “pump enhancer”, but that’s actually just one of it’s jobs.

Citrulline also plays a role in the Urea Cycle, a detoxification process by which Ammonia is converted into Urea and expelled from the body.

Both of these properties–being able to increase NO production and helping rid the body of Ammonia–are what make L-Citrulline such an effective performance enhancement supplements, but it has other benefits as well…

What Are The Proven Benefits Of L-Citrulline?

L-Citrulline Proven Benefits

Although it’s relatively unknown to most people, L-Citrulline has actually been studied fairly extensively over the years.  Especially with regards to exercise and performance enhancement.

This has earned Citrulline a place as a key ingredient in amino acid and pre-workout supplements, but the benefits extend outside of the gym as well.

At this point, L-Citrulline has been proven to do much more than just improve workout performance, but we may as well start there since that’s what it’s known for…

L-Citrulline Increases Muscular Endurance

Citrulline has been shown to increase muscular endurance.

More specifically, it increases the amount of reps you can do towards the end of your workout, when muscular fatigue would ordinarily be setting in.

You see, muscle fatigue is partially caused by Ammonia build-up in muscle tissue.  Citrulline, being a key player in the Urea Cycle, can reduce the amount of Ammonia that builds up in muscle tissue.

Just to be clear, muscular endurance isn’t the same thing as strength…

  • Greater strength is being able to put up more weight.
  • Greater endurance is being able to put up a given weight more times.

So to say that Citrulline increases your strength would be false, but that doesn’t mean it won’t help you get stronger over time.

As long as you stick to the principle of progressive overload–that is, continually increasing the amount of weight you lift over time–supplementing with Citrulline can be quite useful.

More reps and more sets = greater gains over time.

L-Citrulline Increases Nitric Oxide

Remember earlier?

We talked about how Citrulline is the direct precursor to the amino acid L-Arginine which is the immediate precursor to Nitric Oxide.

We also mentioned that Nitric Oxide supplements are one of the most sought after kinds of workout supplements.

Well, that’s because anything that increases Nitric Oxide levels can potentially increase blood flow, causing some pretty nice pumps during workouts.

Unfortunately, most “nitric oxide supplements” don’t really work.

L-Arginine is a perfect example.

One would think that, since Arginine is actually closer to Nitric Oxide than Citrulline, supplementing with Arginine would be a better idea.

Makes sense, but it isn’t true…

Studies which have looked at how Arginine impacts performance enhancement, blood flow, and nitric oxide production have failed to find any real benefit.

There’s no doubt about it…

As a supplement, Citrulline is superior to Arginine.

This is because Arginine is subject to breakdown by the enzyme Arginase.

L-Citrulline, on the other hand, is not.  It bypasses this enzyme, then converts into Arginine which converts into Nitric Oxide.

If it’s better pumps and fuller muscles you’re after, you want L-Citrulline, not Arginine.

L-Citrulline Improves Cardiovascular Health

Given it’s role in Nitric Oxide production, it makes sense that Citrulline would be explored as a potential treatment for people with cardiovascular conditions.

And it has…

L-Citrulline has been shown to prevent hypertension in kids recovering from heart surgery but appears to encourage healthier heart function in healthy individuals as well.

It has been shown to prevent increases in blood pressure in people with high blood pressure, but does not lower blood pressure to an unhealthy degree in healthy people.

In other words…

Citrulline helps maintain healthy blood pressure but won’t drop it too low, as so many blood pressure medications (especially blood thinners) may do.

This makes it a natural and safe first-line defense against high blood pressure.

More of a blood pressure “regulator”, if anything.

L-Citrulline Helps With Erectile Dysfunction

Naturally, anything that helps maintain optimal blood pressure is going to attract the interest of Erecetile Dysfunction researchers.

After all, an estimated 40% of men experience ED at some point.

Maybe that’s why Sildenafil (Viagra) is such a widely prescribed drug!  Clearly there’s a market there…

If you’re like most people though, you’d rather try a safe, natural substance that’s be found in watermelon before taking a synthetic drug.

L-Citrulline supplementation has been shown to improve symptoms of ED, even at 1.5 grams daily.  The same dose of L-Arginine has actually failed to have any impact on ED whatsoever.

So yeah, if it’s harder boners you’re after, L-Citrulline is the way to go!

L-Citrulline Reduces Muscle Soreness

One of the most intriguing benefits of L-Citrulline is that which pertains to recovery from exercise.

It’s actually been shown to reduce muscle soreness.

Although this was originally more of a positive side effects noted in one study, several other studies have now confirmed it.

L-Citrulline definitely reduces muscle soreness.

How exactly it works though, remains something of a mystery…

It my have something to do with L-Citrulline reducing free radical damage during workouts.

Free radicals are molecules which cause oxidative damage.  They’re suspected of contributing to muscle soreness, among other things.

Given Citrulline’s role as a free-radical scavenger throughout the body, it makes sense that it would indirectly reduce muscle soreness ordinary caused by free radicals.

Of course, this is pure speculation (albeit, based on solid facts) but the research is pretty clear…

L-Citrulline is an effective supplement for reducing muscle soreness and enhancing exercise recovery.

L-Citrulline And Growth Hormone

Growth Hormone (GH) is involved in a ton of physiological processes including building muscle, burning fat, and supporting immune function.  When you exercise, you naturally secrete more Growth Hormone.

Combined with exericse, L-Citrulline supplementation has been shown to augment the increase in Growth Hormone.

It does not appear to be effective without exercise though.

It can’t be considered a GH-booster really.  More of a GH-augmenter, really.

Also, it’s not clear whether the increase is large enough to really matter in the scheme of things.

Most supplements that “increase Growth Hormone” really only do it to a small degree and for a short period of time.

Citrulline supplementation won’t mimic the effects of taking actual GH or a GH secretagogue, like MK-77.

Still, it’s worth mentioning the relationship.

L-Citrulline May Be Synergistic With Leucine

Leucine is the most important amino acid when it comes to building muscle.

It directly stimulates mTOR, a signaling molecule which tells the body to start building proteins (muscle protein synthesis).

There is some preliminary evidence which suggests Citrulline may enhance Leucine’s signaling of mTOR.

This could potentially mean that L-Citrulline and L-Leucine are synergistic, but it’s an area that remains under-researched at this time.

We need a few more studies before drawing any solid conclusions about how Citrulline actually interacts with Leucine.

Theoretically though, it makes sense to include Citrulline anytime you’re supplementing with Leucine.

Especially when it comes to fasted cardio!

That’s why I included 6g of Citrulline Malate along with 4g of Leucine when I formulated Amino Beyond.

Given the research on either of these supplements alone, they’re worth taking in my opinion.

Given the limited, albeit encouraging research on the combination of Leucine AND Citrulline, I’m a believer.  They go together well and accomplish different but equally important things on their own anyway.

The Different Types Of L-Citrulline Supplements

Citrulline Supplements

You’ll typically find 2 types of L-Citrulline supplements:

  1. L-Citrulline
  2. L-Citrulline Malate

Throughout the research we discussed, we referred to both of these as L-Citrulline, but there is actually a difference between them…

  • L-Citrulline is just free form Citrulline.  
  • L-Citrulline Malate is L-Citrulline bonded with Malic Acid.  

Malic Acid plays a role in energy metabolism in the body.  It may have it’s own inherent benefits, but no studies have really looked at Malic Acid supplementation alone.


The majority of the studies in which Citrulline enhance exercise performance and reduces soreness used L-Citrulline Malate.

So, that’s the recommended form.

L-Citrulline is still effective, but needs to be dosed high enough to actually work.

Citrulline Malate is usually in a 2:1 ratio of Citrulline To Malic Acid.

That means 6 grams of Citrulline Malate would yield 4 grams of Citrulline and 2 grams of Malic Acid.

Needless to say, L-Citrulline and L-Citrulline Malate require different doses to be considered effective.

So let’s discuss how to dose them properly…

L-Citrulline Dosing

L-Citrulline Dosing

Studies have used a combination of L-Citrulline and Citrulline Malate but studies pertaining to exercise have gravitated toward Citrulline Malate for whatever reason.

At this point, enough different doses of Citrulline and Citrulline Malate have been used across enough different studies to carve out a clinical dose (range).

  • If you’re taking L-Citrulline, you want to take 4 or 5 grams.
  • If you’re using Citrulline Malate (2:1), shoot for 6-8 grams.

Unfortunately, due to the fact that Citrulline is expensive, most supplement companies under-dose it.

3 grams of Citrulline Malate won’t cut it!  At least not according the majority of the studies.

It’s possible that low doses of L-Citrulline are effective for certain things, but if you’re using it for anything performance enhancement related, make sure you dose it right.

Make sure you’re paying attention to your supplement facts panels and only buy clinically dosed supplements with NO proprietary blends.

Does L-Citrulline Have Any Side Effects?

Side Effects

Not really…

At doses of 6-9 grams, absolutely no negative or adverse health effects have ever been reported.

This makes sense since Citrulline is simply an amino acid which your body is not only accustomed to, but requires to function properly.

If you were to take “too much” Citrulline, your body would just simply not absorb it.

The worst thing you could do to yourself with Citrulline supplementation is get a stomach ache if you ate like 20 grams in one sitting.

There’s really nothing to worry about with Citrulline.  It’s SUPER safe!

Obviously, this is the part where I say “check with your doctor before taking any supplement”, but the reality is:

Assuming your L-Citrulline supplement is pure and uncontaminated, on a scale from 1-10–1 being entirely safe and 10 being dangerous–Citrulline is a 1.

My Opinion On L-Citrulline

I don’t go to the gym without it.

Usually I take Amino Beyond in a shaker or some kind of what bottle and sip on it on my way to the gym and during the warm-up part of my workout.

It’s fine to take it with your pre-workout supplement too.

Whatever gets it into your body so that it can be utilized during the intense parts of your workout, when you need it most.

As far as I’m concerned, L-Citrulline is a must-have supplement when it comes to working out.

This isn’t just a matter of me agreeing with the research (although I typically do).  I’ve worked out with it, without it, with different doses, intra-workout, pre- workout, whatever.

I’ve experimented with Citrulline (Malate) ALOT and I can honestly say that it makes a noticeable difference when it comes to squeezing out those last couple reps, pumps, and recovery.

I see several reasons to use Citrulline and zero reasons not to…

The Bottom Line On L-Citrulline

The Bottom Line On L-Citrulline

If you want to get the most out of each and every workout, you want to supplement with L-Citrulline.

It’s been scientifically proven to:

  • Increase Muscular Endurance (More Reps, More Sets)
  • Reduce Muscle Soreness (Faster Recovery)
  • Increase Blood Flow (Better Pumps)
  • Benefit Cardiovascular Health
  • Treat ED

And it may even be synergistic with Leucine with regards to building muscle (more studies are needed in that area).

What’s more, it’s entirely safe!

Next time you reach for a pre workout or BCAA supplement, make sure it has a clinical dose of Citrulline (Malate) in it.

L-Citrulline is one supplement that is well-researched and, quite clearly, well worth it.

Any thoughts on L-Citrulline?  Comment Below…

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