L-citrulline supplements are used to enhance physical performance and increase levels of arginine in the blood. This supplement has been shown to increase Nitric Oxide and Growth Hormone levels, which may support muscle growth for bodybuilders.
L-citrulline is an amino acid that plays several important roles in the body.As an intermediate in the urea cycle, it helps to rid the body of ammonia.
Citrulline results as a byproduct of the conversion of arginine (another amino acid) into NO (nitric oxide). Nitric oxide is a powerful vasodilator; required for maintaining proper blood pressure levels.
As a Nitric Oxide booster, citrulline supplements may improve circulation throughout the body and boost nutrient delivery to muscle cells. This compound is taken as a pre-workout supplement to improve muscle pumps when lifting heavy weights.



- Shown to raise blood arginine levels
- Increases Nitric Oxide & Growth Hormone
- Delays onset of fatigue during intense training
L-Citrulline Supplements
Related Topics
- L-Citrulline
- Citrulline Malate
- L-Citrulline Supplements
- L-Citrulline Benefits
- Citrulline Malate Effects
- L-Citrulline Dosages
- Citrulline Malate Dosages
- L-Citrulline Foods
- Potential Side Effects
- Citrulline for Bodybuilding
- L-Citrulline for Depression
- Citrulline Malate Reviews
- Primaforce Citrulline Malate
- L-Arginine vs. L-Citrulline
Citrulline is an non-essential alpha-amino acid. It is non-proteinogenic, meaning it is not used in protein synthesis. As a supplement, it is typically sold in the form of Citrulline Malate and can be purchased in bulk powder, tablet or capsule form.
This amino acid also occurs naturally in certain foods. Watermelon is the best L-citrulline food source, containing between 0.7-3.6 mg per 1-gram serving. Cucumbers and certain other melons also contain citrulline, in lesser amounts.
Inside the body, L-citrulline is synthesized from both ornithine and glutamine. This occurs in intestinal mucosa.
L-citrulline supplements and endogenous citrulline both travel through the liver without being changed. When citrulline reaches the kidneys, it is converted to L-arginine and then released into the circulatory system.
Subsequently, L-arginine is converted to NO. This conversion occurs inside the inner linings (endothelium) of the blood vessels, as well as various other tissues and organs. L-citrulline is also created as a byproduct of this conversion process.
Uses of L-citrulline Supplements
Oral use of L-citrulline supplements can help to elevate NO availability in the body. NO helps circulatory vessels to relax and dilate. This relaxes erectile tissue and smooth muscle tissues throughout the body.
By expanding in diameter, these vessels are able to deliver more blood without increasing blood pressure. This can have a positive effect on circulation, nutrient delivery to muscles, sexual function and more.
L-citrulline is a non-essential amino acid, meaning that we do not need to consume dietary sources of this compound to prevent deficiency. However, there may be health benefits associated with increasing your intake of this product.
According to the Natural Medicines Comprehensive Database (NMCD), taken orally, L-citrulline (2-Amino-5-(carbamoylamino)pentanoic acid) supplements are used for Alzheimer’s disease, hypertension (high blood pressure), diabetes mellitus, muscular weakness, ED (erectile dysfunction), impotence, heart failure, sickle cell disease and Reye’s syndrome.
L-citrulline may also be used for vascular disease, fatigue, poor immune system functioning, cardiovascular disease, lysinuric protein intolerance, postoperative pulmonary hypertension and certain other conditions and diseases.
In children, L-citrulline may be used intravenously to prevent pulmonary hypertension following heart surgeries.
L-citrulline Supplement for Hypertension
Increasing L-citrulline consumption results in higher levels of L-arginine in the blood. Increasing L-arginine results in an increase in NO synthesis.
NO induces vasodilation, which can result in lower blood pressure as blood vessels can carry more blood throughout the body when they are dilated.
Research suggests that an L-citrulline supplement can be helpful for decreasing blood pressure in those with prehypertension. Prehypertension is marked by slightly elevated blood pressure levels (between 120/80 to 139/89). The condition increases risks for heart disease and hypertension.
In one double-blind human trial, overweight middle-aged men were given 5600 mg of an L-citrulline supplement each day for 7 days. Asides from being overweight, all subjects were healthy.
After 7 days, blood flow was increased secondary to increased Nitic Oxide concentrations. This improvement in blood flow was attributed to increased L-arginine levels.
L-citrulline for Erectile Function and Circulation
Improving blood flow with a L-citrulline supplement may help to alleviate certain symptoms of mild-to-moderate ED, particularly when caused by hypertension.
Research has shown that it acts similarly to the active molecule in Viagra (sildenafil citrate). While it is not as effective for ED as sildenafil, it may present a safer treatment option.
Research in animals shows that L-citrulline supplements can help to prevent and/or treat certain blood vessel disorders. This may prove to be helpful for improving various conditions.
For example, slow wound healing capacities in those with type 2 diabetes mellitus may be improved with regular L-citrulline supplementation.
L-citrulline for Improving Athletic Performance
Many athletes use L-citrulline supplements to improve cardiovascular efficacy, and certain sports performance markers. Research has shown that L-citrulline administration can reduce fatigue. It has also resulted in performance improvements in both aerobic and anaerobic endurance exercise.
In a double-blind trial involving 41 trained male weightlifters, using a L-citrulline supplement for 7 days delayed fatigue, increased total work and facilitated recovery from post workout muscle soreness. In this study, 8 g doses of oral citrulline malate were administered daily.
Animal research suggests that using a L-citrulline supplement can elevate intramuscular protein levels. This could help to avoid muscular weakness and wasting (cachexia), and malnourishment, especially in elderly persons.
There are various other therapeutic potentials associated with L-citrulline supplement usage. Research continues to explore its gastroprotective, hepatoprotective, renoprotective, and cardioprotective traits.
L-citrulline Supplement Safety
The NMCD reports no adverse effects associated with L-citrulline. However, usage may affect the ways certain drugs are metabolized in the body. Do not use in conjunction with nitrates for heart disease, or other medications that can alter blood pressure; like Viagra, Cialis, Levitra and others.
Pregnant and nursing women should avoid using L-citrulline supplements. Not enough reliable research has been completed to determine safety for these groups.
L-citrulline supplements are rated as “possibly safe” in healthy adults when used properly and orally. Doses in excess of 8 grams daily have been used for as long as 9 months without causing adverse effects. One-time doses up to 15 grams have also been used safely.
In children, proper, oral usage is also rated as possibly safe. 5.7 grams have been used daily for as long as 20 months with no side effects.
To be sure that L-citrulline supplements are safe for you, it is best to talk to a doctor who knows about your health history and medications.
- Pérez-Guisado J1, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res. 2010 May;24(5):1215-22. doi: 10.1519/JSC.0b013e3181cb28e0.
- Figueroa A1, Trivino JA, Sanchez-Gonzalez MA, Vicil F Oral L-citrulline supplementation attenuates blood pressure response to cold pressor test in young men. Am J Hypertens. 2010 Jan;23(1):12-6. doi: 10.1038/ajh.2009.195. Epub 2009 Oct 22.
- Ochiai M1, Hayashi T, Morita M, Ina K, Maeda M, Watanabe F, Morishita K. Short-term effects of L-citrulline supplementation on arterial stiffness in middle-aged men. Int J Cardiol. 2012 Mar 8;155(2):257-61. doi: 10.1016/j.ijcard.2010.10.004. Epub 2010 Nov 9.
- Orozco-Gutiérrez JJ1, Castillo-Martínez L, Orea-Tejeda A, Vázquez-Díaz O, Valdespino-Trejo A, Narváez-David R,Keirns-Davis C, Carrasco-Ortiz O, Navarro-Navarro A, Sánchez-Santillán R. Effect of L-arginine or L-citrulline oral supplementation on blood pressure and right ventricular function in heart failure patients with preserved ejection fraction. Cardiol J. 2010;17(6):612-8.
Article last updated on: March 12th, 2018 by Nootriment