What if I told you there is a supplement out there in the vast wild west known as the health industry that can improve cognitive health, improve exercise performance, improve blood flow, and more? Would you be interested in learning about this supplement? If so, you’ve come to the right place. L-citrulline has been gaining popularity in fitness circles recently for its possible benefit of improving exercise performance. If you’re reading this, chances are you care about more than your post-workout pump. L-citrulline has a host of other potential benefits as well as risks. We will explore the ins and outs of L-citrulline so you have all the facts. Let’s go over everything you could ever need to know about this supplement and see if it’s worth adding to your health and wellness protocols.


What Is L-Citrulline?

L-citrulline is an amino acid that occurs naturally in the body. Foods such as watermelon and pumpkin seeds contain high levels of L-citrulline. Since the body produces L-citrulline naturally, we call it a nonessential amino acid. Even though L-citrulline is an amino acid, it does not directly impact protein synthesis. However, it still has value in other processes within the body. L-citrulline could also potentially increase chemicals in the body that aid in protein synthesis. One such chemical process L-citrulline is a vital component of is the urea cycle. This cycle is responsible for flushing harmful compounds such as ammonia from the body. Urine flushes out the urea that remains. So now you know what L-citrulline is, let’s look at how it works.


How Does L-Citrulline Work?

We know that L-citrulline is an amino acid produced in the body and used for various body processes. One of those processes is vasodilation. Vasodilation is the relaxing and widening of blood vessels. This process is made possible via the conversion of L-citrulline into another amino acid, L-arginine. When this happens, L-arginine gets converted into nitric oxide. This in turn promotes vasodilation thanks to the relaxing of cells within the blood vessels. A popular question amongst nutrition experts is: “why should we supplement L-citrulline for vasodilation when it’s converted into L-arginine anyway?” Why not just supplement L-arginine?

This is a fair question, and maybe one you are asking as well. What researchers found is the body seems to better absorb L-citrulline, or at least differences in absorption rate demonstrate consuming L-citrulline may increase the bioavailability of L-arginine better than consuming L-arginine itself. We have already touched on a couple benefits of L-citrulline, but let’s dive a little deeper now.


What are the benefits of L-Citrulline?

L-citrulline has had research conducted to look into the potential benefits for various areas of health. This includes cognition, sexual health, exercise performance, fatigue recovery, blood flow, etc. Let’s dive into the benefits of L-citrulline so you can see why it may be smart o add it to your supplement stack.


Improved Blood Flow

The first benefit is the most obvious benefit, and the benefit discussed most often. L-citrulline may improve the expansion of blood vessels via vasodilation. This vasodilation can make blood flow more efficiently throughout the body. As a result of this more efficient blood flow, delivery of oxygen and nutrients to the muscles and other cells of the body also improves. As the delivery of nutrients and oxygen improves, so does the removal of waste materials in those muscles and cells. as a final note, it is worth stating that a single dose is unlikely to yield any significant results, so continual supplementation has a far greater likelihood of benefit. This is especially true if you have any underlying heart health issues.


Reduced Blood Pressure

If you have any hypertension issues, L-citrulline may come in handy. There is some research showing L–citrulline may help lower blood pressure, especially if you have high blood pressure. There is less research supporting improved blood pressure for already healthy individuals, but rest assured there are other benefits for you.


Better Pump

A side benefit to better blood flow is the improved delivery of oxygen and nutrients to cells of the body; this includes muscle cells. When blood flows faster into muscles, this creates a fuller and thicker appearance. Bodybuilders call this thicker and fuller appearance the “pump.” The pump creates a full and defined physical appearance, which is the ideal look competitive bodybuilders chase for stage competitions as well as photoshoots. If you are trying to achieve this particular look, supplementing L-citrulline might be useful.


Increase of GH Production

For those of you looking to add some muscle mass to your physique, L-citrulline might have another benefit for you. There is some research that suggests supplementing L-citrulline (particularly citrulline malate) can promote growth hormone production during and after your workout. As growth hormone production increases, your recovery time improves and you are likely to see muscle growth faster. There are plenty of other factors that do more for growth hormone production, but supplementing L-citrulline can certainly be complementary to other factors such as improving sleep quality, reducing sugar intake, eating more protein, etc.


Increased Energy Levels and Improved Exercise Performance

We all want to be able show to every workout with high energy and crush it with crazy intensity. I’m sure most of you would also love to have enough energy everyday to not need the morning cup(s) of coffee and/or a 3pm nap just to function like a human most days. Lucky for you, L-citrulline might be able to help. Some consumers of L-citrulline have reported increased energy levels, which is why L-citrulline is a common ingredient in pre-workout mixes. Supplementing L-citrulline increases production of ATP (adenosine triphosphate), which is likely a major contributor to this benefit. Increasing ATP leads to an increase in energy and improved fatigue resistance.

L-citrulline research has looked at multiple styles of exercise to establish exercise performance benefits. Researchers have looked at High Intensity Interval Training (HIIT), Endurance Training, and General Strength Training to see the effects of L-citrulline. A variation of L-citrulline called citrulline malate has been studied alongside L-citrulline. The only difference you need to know is that citrulline malate contains malic acid, which can improve absorption rate and bioavailability of L-citrulline in the body. This of course improves energy levels by making more energy available to be used.

To briefly sum up the gist of the research, L-citrulline seems to be more useful for endurance training while citrulline malate seems to be more useful for strength training and HIIT training. Regardless of which variation of citrulline you choose to supplement, they will likely give you more energy to push yourself harder during the workout and recover faster after the workout.


Improved Brain Function

We have established that L-citrulline not only aids in vasodilation (widening of blood vessels, but is a precursor to nitric oxide (NO), a molecule responsible in part for intracellular signaling. This intracellular signaling includes the neurons in the brain. Put these two things together, and you see the importance of L-citrulline for brain health. L-citrulline can improve the delivery of oxygen, blood, and nutrients to the brain the same as it does to other areas of the body. Potential side effects of this are sharper focus, feeling more alert, and improved mood.


Improved Sexual Health

This potential benefit varies amongst studies and is inconclusive, but there is some research showing a decrease in mild erectile dysfunction symptoms. There is also some potential improvement in the ability to maintain an erection. This is likely due to the increased blood flow via vasodilation from the L-citrulline being converted into nitric oxide.


Taking L-Citrulline

Different studies will tell you different amounts, but a generally accepted amount of L-citrulline (for blood pressure and/or endurance training) would be 3-6 grams daily. Some research that suggests if you take citrulline malate (strength training/HIIT) instead, a slightly higher dosage of up to 8-10 grams a day could be beneficial. There is little feedback from consumers of side effects such as upset stomach, so taking 8-10 grams a day should not warrant any negative effects. There is also little to no reported benefit to exceeding 10 grams per day.


Side Effects and Safety Concerns

Preliminary research has been conducted in regard to excessive L-citrulline consumption. Thankfully there seems to be no reported negative side effects of consuming up to 15 grams per day routinely. There are no reported benefits to exceeding the 8-10 grams per day recommendation either. No research has shown any negative impacts on body function or blood pressure. Furthermore, there is evidence that exceeding 10 grams per day likely leads to the body flushing the excess L-citrulline, so it appears to be a waste of time and money to exceed 10 grams per day.


The Crux Of The Matter

Here’s the bottom line: L-citrulline is an amino acid with an array of health benefits. This amino acid can provide energy to crush the toughest workouts, improves blood flow, helps promote nitric oxide, improves brain health, and more! You have plenty to gain and almost nothing to lose by adding L-citrulline to your supplement stack. If you want to improve heart health and be able to train harder, L-citrulline is a solid bet. Like I previously stated, many pre-workout mixes contain L-citrulline, so you are unlikely to need to supplement it by itself.