L-Citrulline

It has the ability to improve focus, strength, and stamina. Furthermore, it also shows to prevent neural cell death while protecting blood vessels within the brain. In some cases, l-citrulline is an organic compound found within the family of non-essential amino acids.

As a whole food, you’ll find citrulline in beetroot, garlic, and some meats. L-citrulline is commonly supplemented with malate to form citrulline malate, which is known to improve sports performance. It’s is an important amino-acid as it not only improves physical performance, but it also assists the body with the urea-cycle which is the removal of toxins from the body.

Benefits of L-Citrulline

Supplementing with l-citrulline can delay the onset of fatigue while improving endurance in aerobic and anaerobic activities. This means that activities such as sprinting and long-distance exercises can be improved with the use of l-citrulline.

You may have seen citrulline malate before in some supplements. As a natural process in the body, this is a component of the ‘tricarboxylic acid cycle’ which can increase aerobic metabolism. It does this by reducing lactic acid production allowing you to train harder for longer. (III) Furthermore, l-citrulline works together with l-arginine and l-ornithine – these amino acids are present in the urea cycle (removal of waste via urination).

Together, these assist the body in a number of ways. Such as the removal of toxins, and as already mentioned, the increase of nitric oxide in the body. This allows for more nutrients to be shuttled into your working muscles which extends performance while removing waste products such as lactic acid and other substrates associated with waste products that are built up from exercise.

Not only that, but l-citrulline can also improve strength while increasing growth hormone production. And also, the strength of erections in men. Furthermore, l-citrulline can work in a short space of time thanks to its ability to cross the blood-brain barrier, making it quick to act throughout the body.

Benefits to L-citrulline Supplementation:

• Increased strength
• Improves levels of stamina
• Reduces erectile dysfunction
• Helps recover sore muscles
• How L-citrulline Works in the Body

Increases Nitric Oxide Production

The body creates l-citrulline within the liver and the small intestines. It’s is the most common byproduct of the precursor l-glutamine. L-citrulline then gets converted to l-arginine, which continues to be converted into nitric oxide.

L-citrulline is produced through a process called the citrulline-NO cycle. (IV) It’s during this process that l-citrulline is created when a byproduct of NO is released (arginine). Arginine can then be converted back to l-citrulline in an ongoing cycle. (V)

It’s nitric oxide’s role to help blood vessels dilate and transport oxygen around the body which assists sports performance. So, does that mean you can skip L-citrulline and take L-arginine to boost nitric oxide levels? Not so fast!

You might want to know that taking large amounts of l-arginine on its own may cause side effects. Such as; stomach pains, diarrhea, headaches, and nausea to name a few. This makes l-citrulline a more favorable option for improved performance.

Removes Unwanted Toxins

As previously mentioned, the urea cycle is vital to the human body as it removes unwanted toxins via urination. If toxins aren’t removed, such as the ones built up in oxidative stress during and after exercise, then, recovery could be hampered. As soon as l-citrulline is present in the body, the kidneys then convert it to l-arginine, which helps you to recover quicker by removing harmful waste products.

As mentioned, it’s the responsibility of the kidneys to release l-arginine into the bloodstream and throughout the body assisting in the removal of unwanted toxins. When this process takes place, complete availability of the amino acid takes place, allowing you to reap its full benefits – such as increased blood and oxygen supply to your working muscles. (VI, VII).

Increases Growth Hormone and IGF-1

A study which took trained athletes and gave them 6g of citrulline malate prior to a prolonged cycling test of 137 km – saw improvements in overall performance and growth hormone (GH) levels. After completion, further results were collected which showed that 66.8% increase in GH was found after 3 hours of rest in total. (VIII)

To highlight these results: When using l-citrulline, you’ll be able to increase muscle growth and weight loss. This is down to the way citrulline enhances growth hormone production post-exercise – growth hormone being responsible for incredible body composition and sports performance adaptations.

Strength Improvements

In one study when weightlifters were given 8g of citrulline malate alongside 10g of sucrose (a form of carbohydrate), they were able to increase the number of reps per set – 10.48% to 52.92% more reps. (IX)

The same study also recorded that nonresponders (people who don’t respond to supplementation) didn’t see any changes in the first set. However, all participant (including the original nonresponders) saw some benefits on the eighth set of the chosen exercise. (X)

This is incredible, as for people who were originally nonresponders can now take citrulline knowing that it ‘does’ work after longer sets of exercise. Which is great news for anyone who trains with intensity or for longer durations.

Reduced Muscle Soreness

For those who are focused on resistance or high-intensity weight training, such as bodybuilding. L-citrulline offers some relief from muscle soreness and recovery.

Muscle soreness has been shown to be reduced after taking 8g of citrulline malate prior to weight training. The total amount of reduced muscle soreness in one study showed a 39.74% decrease after 24 hours, more so 48 hours later at 41.79%. (XI)

Long story short, if you want to build muscle but you hate delayed onset muscle soreness (also known as DOMS) – taking citrulline you can cut down your muscle aches and pains by almost half!

Improved Erections For Men

L-citrulline supplementation has been proven to be safe and psychologically well accepted by patients suffering from erectile dysfunction.

In a study published by the Department of Urology and Renal Transplantation found that after one month of using l-citrulline, their sexual stamina, frequency, and erection ‘hardness’ improved. (XII)

With as little as 1.5 g per day (the amount used in the study) showed improvements in the sexual life of older men. From this study, we can see that l-citrulline is a powerful libido enhancer.

Ideal Dosages

As we’ve just discovered, taking as little as 1.5 g a day can be beneficial for sexual performance in older men. However, other studies suggest dosing at 15 g for improved sports performance and muscle recovery are even better.

However, this doesn’t mean more is better. Taking large amounts above 20 g per dosage could cause stomach upset. So, if in doubt, stick to the recommended 15 g or below per day, or when needed. (XIII)

References

(I) “Citrulline.” Wikipedia, Wikimedia Foundation, 21 Jan. 2019. (source)

(II) Oketch-Rabah, Hellen A, et al. “The Importance of Quality Specifications in Safety Assessments of Amino Acids: The Cases of l-Tryptophan and l-Citrulline.” The Journal of Nutrition, U.S. National Library of Medicine, Dec. 2016. (source)

(III) Pérez-Guisado, Joaquín, and Philip M Jakeman. “Citrulline Malate Enhances Athletic Anaerobic Performance and Relieves Muscle Soreness.” Journal of Strength and Conditioning Research, U.S. National Library of Medicine, May 2010. (source)

(IV) “Citrulline.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine. (source)

(V) Mori, M, and T Gotoh. “Regulation of Nitric Oxide Production by Arginine Metabolic Enzymes.” Biochemical and Biophysical Research Communications, U.S. National Library of Medicine, 7 Sept, 2000. (source)

(VI) Eberhardt, Dorit, et al. “L-Citrulline Production by Metabolically Engineered Corynebacterium Glutamicum from Glucose and Alternative Carbon Sources.” AMB Express, Springer Berlin Heidelberg. (source)

(VII) Curis, E, et al. “Almost All about Citrulline in Mammals.” Amino Acids, U.S. National Library of Medicine, Nov. 2005. (source)

(VIII) Sureda, Antoni, et al. “L-Citrulline-Malate Influence over Branched Chain Amino Acid Utilization during Exercise.” European Journal of Applied Physiology, U.S. National Library of Medicine, Sept. 2010. (source)

(IX, X) Pérez-Guisado, Joaquín, and Philip M Jakeman. “Citrulline Malate Enhances Athletic Anaerobic Performance and Relieves Muscle Soreness.” Journal of Strength and Conditioning Research, U.S. National Library of Medicine, May 2010. (source)

(XI, XII) Cormio, Luigi, et al. “Oral L-Citrulline Supplementation Improves Erection Hardness in Men with Mild Erectile Dysfunction.” Urology, U.S. National Library of Medicine, Jan. 2011. (source)

(XIII) Moinard, C, et al. “Dose-Ranging Effects of Citrulline Administration on Plasma Amino Acids and Hormonal Patterns in Healthy Subjects: the Citrudose Pharmacokinetic Study.” The British Journal of Nutrition, U.S. National Library of Medicine, Apr. 2008. (source)