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6 Health Benefits of L-Citrulline


While L-Citrulline doesn’t contribute to protein building, it plays several vital roles beyond that in our bodies. In this article, we look at some L-citrulline benefits, its sources, and how best to use it for your health. Whether you’re an athlete or simply looking to give your well-being a boost, we’ve got something for you.


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What is L-Citrulline?

L-Citrulline is an amino acid made naturally by your body. Although it’s not part of the building blocks for making proteins, it has important roles in our health. The name ‘Citrulline’ comes from ‘Citrullus,’ the Latin term for watermelon, which is where scientists first found this amino acid in 1930.

You can also get L-citrulline from other foods including sour melons, cucumbers, and pumpkins.

The amino acid is also available in supplement form. The two main kinds of supplements are L-citrulline and citrulline malate. L-citrulline is the pure form of this amino acid. Citrulline malate is a mix of L-citrulline and malate, another compound that offers multiple health benefits to the body.

L-Citrulline works in three main ways; vasodilation, reducing amino acid breakdown, and boosting protein synthesis.

In the kidneys, L-citrulline changes into another amino acid, L-arginine. L-arginine helps make nitric oxide, which widens and relaxes blood vessels. This helps blood flow better and lowers blood pressure.

L-citrulline helps your liver get rid of ammonia, a waste product. This helps keep your body from breaking down other amino acids, which helps protect muscle protein.

Finally, L-citrulline boosts protein synthesis by helping your body keep a good balance of nitrogen, which supports the making of new protein molecules.

6 Health Benefits of L-Citrulline

Some of the evidence-based benefits of L-Citrulline include:

1. May improve athletic performance

L-Citrulline can help improve athletic performance in two ways: by improving blood flow and aiding muscle recovery. When L-citrulline is transformed into L-arginine in the body, it produces nitric oxide. This widens blood vessels, allowing more oxygen and nutrients to reach muscles. This process is called vasodilation. Nitric oxide also helps our bodies use glucose more effectively, providing more energy during exercise.

Besides these effects, L-citrulline also supports muscle recovery by helping the body maintain a good nitrogen balance. This is key for the body to make new proteins, which help you build muscle and recover after exercise.

However, it’s important to note that these benefits usually come from regular use of L-citrulline, not just a one-time dose.

In one study, 22 trained males took 2.4 grams of L-citrulline every day for 7 days. On the eighth day, they cycled 4 kilometers after taking either L-citrulline or a placebo. Those who took L-citrulline finished 1.5% faster than those who took a placebo. They also reported feeling less muscle fatigue and better concentration after exercising (*).

In contrast, another study found that a single dose of L-citrulline malate (CM) didn’t improve resistance training performance in regular gym-goers. Participants took either 8 grams of citrulline malate or a placebo before doing weightlifting exercises. The results showed no difference in performance between those who took a supplement and those who took the placebo (*).

Similarly, a study with 10 well-trained males found no performance differences between those who took a single dose of 12 grams of citrulline malate before doing cycling exercises and those who took a placebo. However, this study did find that those who took citrulline malate had significantly higher heart rates during exercise(*).

2. May enhance cardiovascular health

L-Citrulline also supports heart health, mainly by helping your body produce nitric oxide (NO). Even though the body makes NO from L-arginine, taking L-arginine supplements doesn’t work as well because the body breaks down L-arginine in the liver before it can reach the bloodstream. L-Citrulline, on the other hand, bypasses the liver and is converted to L-arginine in the kidneys, promoting NO production.

One study looked at people who took a watermelon supplement with L-citrulline and L-arginine for six weeks. The results showed significant drops in several blood pressure measurements, compared to a placebo (*).

L-Citrulline can also reduce arterial stiffness, which makes it easier for your heart to pump blood (*). In another study, men with a certain level of arterial stiffness took either L-citrulline or a placebo for seven days. The men who took L-citrulline had significantly less arterial stiffness than those who took the placebo (*).

Lastly, there’s evidence from studies in rats that L-citrulline might protect the endothelial lining, which is the thin layer of cells that line the inside of blood vessels (*). This lining plays a big role in heart health. When it’s damaged, it can lead to serious problems like atherosclerosis, the build up of fats like cholesterol along the walls of the arteries.

3. May increase energy levels

L-Citrulline plays a key role in boosting energy levels, making it an essential nutrient for those needing an extra push during the day or for athletes seeking better performance.

It helps increase energy levels through a process called the urea cycle. This cycle removes waste products like ammonia from the body. If there’s too much ammonia in your body, it can make you feel tired and sluggish. By helping your body get rid of this ammonia, L-citrulline can help you feel more energetic.


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Moreover, as we’ve discussed earlier, L-citrulline boosts the production of nitric oxide, which has a vital role in oxygen and nutrient delivery to your muscles. The more oxygen and nutrients your muscles get, the more energy they can produce.

4. May improve erectile function

While research into L-Citrulline’s effects on erectile function is still limited, early findings are promising. Erectile dysfunction (ED) is often caused by poor blood flow to the penis. This is where nitric oxide comes into play, as it relaxes and opens up blood vessels, allowing for better blood flow. Moreover, research shows that men with ED tend to have lower levels of L-Citrulline in their blood (*).

One study asked men with mild ED to take L-Citrulline for a month. The results showed that the number of successful sexual encounters increased significantly when taking L-Citrulline compared to a placebo. Also, half of the men improved their erection hardness score from mild ED to normal erectile function (*).

Another study combined L-Citrulline with transresveratrol, a supplement known for its heart health benefits. Men with ED who were already using ED medications participated. The results showed that L-Citrulline and transresveratrol significantly increased the Sexual Health Inventory for Men score, which measures erectile function, compared to both baseline and placebo. However, the improvement in erection hardness was not significant (*).

5. May aid in muscle recovery

L-Citrulline plays a crucial role in muscle recovery due to its involvement in waste removal. Our muscles produce waste products like lactic acid during exercise, which contributes to muscle soreness and fatigue. L-Citrulline helps remove these waste products, promoting quicker recovery.

Additionally, L-Citrulline possesses antioxidant and anti-inflammatory properties that may further help in muscle recovery (*). These properties can help reduce the inflammation and oxidative stress that’s typically experienced during strenuous physical activity.

A systematic review, which analyzed various studies about the effects of L-Citrulline on muscle recovery, showed promising results. In this review, researchers examined studies involving healthy individuals who took L-Citrulline supplements up to 2 hours before exercise.

Results revealed that L-Citrulline significantly reduced feelings of physical exertion and muscle soreness 24 and 48 hours after exercise. However, it didn’t significantly reduce muscle soreness 72 hours post-exercise or lower blood lactate levels (*).

6. Potential immune support

Arginine plays a key role in the immune response, as it helps regulate the function and development of certain immune cells. However, supplementing directly with arginine can be ineffective due to its rapid breakdown in our bodies, which is where L-Citrulline comes in. As we saw earlier, L-Citrulline is converted into arginine in our bodies, providing a more stable and reliable source of this crucial nutrient.

Research on L-Citrulline’s effects on the human immune system is limited, but animal studies have shown promising results. For instance, in a study involving infant rats, both L-Citrulline and L-Arginine were given for a week.

The results showed that both supplements improved immune response. The supplements boosted the activity of T-cells which are the cells responsible for identifying and removing foreign bodies like bacteria and viruses. The L-Citrulline supplement group also showed an increase in TGF-β, an important factor that is essential for cell growth and multiplication (*).

Frequently Asked Questions

Can you take L-Citrulline everyday?

Yes, you can take L-citrulline everyday as it is generally regarded as safe for a healthy adult. Multiple studies have given their subjects daily L-citrulline doses and saw no adverse effects (*, *).

Can you get L-Citrulline from natural foods?

Yes, you can get L-Citrulline from natural foods such as watermelon, cucumber, and pumpkin. However, the dose might be ineffective to achieve certain benefits such as boosted athletic performance.

For example, you would need to eat about 1-1.5 kilograms of watermelon a day to get an effective dose of L-citrulline (*).

What are the side effects of taking L-Citrulline?

Some of the side effects of taking L-Citrulline include heartburn and digestive upset. However, these are very rare especially if you take it in moderate amounts. You should however not pair L-citrulline with other blood pressure medication as this could result in very low blood pressure.

When is the best time to take L-Citrulline?

You should take L-Citrulline about one hour before exercise. However, since its effects are often seen in the long term, you can get away with taking it at any time of day as long as you are consistent.

How long does it take for L-Citrulline to take effect?

L-Citrulline takes about an hour to have a positive effect on physical performance. However, this can vary significantly from person to person.

How long does the L-Citrulline effect last?

The effects of L-Citrulline last anywhere from 30 minutes to two hours after you take it (*). However, you can still benefit from the supplement just by taking it daily and no specifically before a workout (*).


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The Bottom Line

All in all, L-citrulline offers many health benefits. While it is naturally available in food, you need to supplement your intake to reach an effective dose. You may choose to take a daily L-citrulline supplement or incorporate it into your pre-workout snack line up. The Perfect Keto Pre-workout Drink contains 500 mg of L-Citrulline, more than enough to give you a boost in performance and overall cardiovascular health.

18 References

Takashi S et al. Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men: Double-blind randomized placebo-controlled 2-way crossover study. 2016 February 19

Andrew J et al. Citrulline Malate Fails to Improve German Volume Training Performance in Healthy Young Men and Women. 2018 November 21

Brian C et al. Acute Citrulline-Malate Supplementation and High-Intensity Cycling Performance. 2016 September

Arturo F et al. Effects of watermelon supplementation on aortic blood pressure and wave reflection in individuals with prehypertension: a pilot study. 2010 July 8

Arun M et al. Effects of L-Citrulline Supplementation on Endothelial Function and Blood Pressure in Hypertensive Postmenopausal Women. 2022 October 20

Masayuki O et al. Short-term effects of L-citrulline supplementation on arterial stiffness in middle-aged men. 2012 March 8

Amal A et al. The effect of L-arginine or L-citrulline supplementation on biochemical parameters and the vascular aortic wall in high-fat and high-cholesterol-fed rats. 2011 June 3

A Barassi et al. Levels of l-arginine and l-citrulline in patients with erectile dysfunction of different etiology. 2017 February 8

Luigi C et al. Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction. 2011 January

Masato S et al. Oral L-citrulline and Transresveratrol Supplementation Improves Erectile Function in Men With Phosphodiesterase 5 Inhibitors: A Randomized, Double-Blind, Placebo-Controlled Crossover Pilot Study. 2018 August 24

Kirsten E et al. Investigation into the antioxidant capacity of L-arginine and L-citrulline in relation to their vascular protective properties. 2007

Hye Ch et al. Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis. 2020 December

Yi-Chen L et al. L-Arginine and L-Citrulline Supplementation Have Different Programming Effect on Regulatory T-Cells Function of Infantile Rats. 2018 December 10

Alberto C et al. L-Citrulline Supplementation and Exercise in the Management of Sarcopenia. 2021 September 8

Arun M et al. Effects of L-Citrulline Supplementation on Endothelial Function and Blood Pressure in Hypertensive Postmenopausal Women. 2022 October 20

Timothy D et al. l-Citrulline Supplementation: Impact on Cardiometabolic Health. 2018 July 19

Hye C et al. Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis. 2020 December

Alberto C et al. L-Citrulline Supplementation and Exercise in the Management of Sarcopenia. 2021 September 8


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