Scientific studies show the combination of L-Citrulline and L-Arginine increases Nitric Oxide production for cardiovascular, immune boosting, and sexual health benefits!
You have probably heard of the amino acid L-arginine, which is also called simply arginine.
If you eat at least six cups of watermelon every day then you’re getting an adequate dose of the amino acid citrulline. Citrulline’s name is actually derived from the Latin word for watermelon—citrullus—because it was first isolated from the fruit in 1930.1
What does L-Citrulline and L-Arginine do?
Together they help:
- Support cardiovascular health by boosting nitric oxide production and helping blood flow more easily throughout the body
- Support healthy blood pressure and boost the immune system
- Detoxify the liver and eliminate ammonia from the body
- Improve sexual stamina and enhance recovery from an intense workout
Who might benefit from taking a supplement containing
both citrulline and arginine?
- Anyone who wants to support healthy blood pressure Individuals who want to avoid angina (chest pain)
- Individuals who want to avoid leg pain due to poor blood circulation
- Anyone who wants protection from heart attack and stroke
- Men suffering from erectile dysfunction
- Athletes who want a faster recovery
How are citrulline and arginine related?
As soon as citrulline enters the kidney, vascular endothelium and other tissues, it is converted into arginine. Plasma and tissue levels of arginine increase, which is necessary for the production of nitric oxide and relaxation of blood vessels. An additional benefit of supplemental citrulline is that it helps eliminate ammonia, a highly toxic substance, from the liver.
Will citrulline and arginine help my sex life?
The answer is yes. Arginine has been well studied for its ability to enhance sexual satisfaction. Both men and women report longer and more intense orgasms when their intake of arginine increases. Additionally, arginine is often used by men to achieve long lasting and harder erections. Since citrulline is a precursor for arginine and arginine is a precursor to nitric oxide, you can combine the two for enhanced sexual pleasure and vascular health.
But you’re probably not eating six cups of watermelon every day, and actually it isn’t recommended. Watermelon is high in fructose (fruit sugar) and it’s a natural diuretic, so you’d be spending a whole lot of time in the bathroom.
In addition to watermelon, citrulline is found in cucumbers and cantaloupe, at very low levels, as well as the milk protein casein. But since it is a nonessential amino acid, you don’t have to rely on getting citrulline from food. It is manufactured from other nutrients in your body, however, you only manufacture it if you are young
and healthy and producing those other essential nutrients in adequate amounts!
The citrulline and arginine combination plays an essential role in your body
Citrulline, like arginine, is important in vasodilation, the widening of blood vessels, resulting from relaxation of smooth muscle cells within the vessel walls, especially in the large arteries and veins and smaller arterioles.
The endothelium (inner lining) of blood vessels uses nitric oxide to signal the surrounding smooth muscle to relax. This results in a relaxing of the blood vessels, and increased blood flow.
In the body, citrulline is converted to the amino acid arginine, which goes on to make another important substance—nitric oxide. When citrulline enters the kidney, vascular endothelium and other tissues, it can be readily converted to arginine, thus raising plasma and tissue levels of arginine and enhancing nitric oxide
The importance of nitric oxide to healthy blood flow
As stated, nitric oxide is integral to relaxing blood vessels which is necessary for healthy blood flow to the heart and genital area in both men and women, and throughout the body. Nitric oxide helps the blood vessels maintain their flexibility so that the blood flow is unrestricted. This, in turn, helps maintain healthy blood pressure, and a healthy sexual response.
When your vascular system is working efficiently there is less chance that a blood clot will form, which means there is less chance of having a heart attack or stroke.
Nitric oxide helps prevent blood clots because it prevents blood aggregation or platelets from becoming sticky. When platelets are not sticky they can move in a single file through the capillaries.
But if they are sticking together it’s like trying to move a dozen people through a crack in the wall. There is nowhere for the platelets to go, so a blood clot forms.
Additionally, nitric oxide works as an antioxidant that reduces the possibility of immune cells adhering to artery walls. This helps keep down inflammation,
which most health professionals agree is a major cause of the plaque formation that contributes to atherosclerosis.
What inhibits adequate nitric oxide production?
- People who have atherosclerosis, diabetes or hypertension (high bloodpressure) often show impaired nitric oxide pathways.3
- Over-consumption of salt can impair nitric oxide production.4
- Aging—as we get older there is a decrease in nitric oxide production because the body makes less citrulline and arginine.5
Boosting nitric oxide production with nutritional supplements
Supplemental arginine helps the body produce more nitric oxide, and it helps with conditions that improve when blood vessels are relaxed, such as atherosclerosis
and intermittent claudication (difficulty walking due to pain in leg muscles because of inadequate blood supply).
Even more importantly, new studies are showing that supplemental citrulline also assists in nitric oxide production by boosting blood levels of arginine. It does this because it is more readily absorbed and bioavailable than arginine alone, and it bypasses metabolism in the liver and gastrointestinal tract and is readily absorbed in the kidneys.6, 7
Citrulline and argininescientific studies
In the first study to show that oral supplementation with citrulline raises blood levels of arginine, 20 healthy volunteers were given 6 different dosing regimens of placebo, citrulline, and arginine.
After one week of oral supplementation, the citrulline dose increased plasma arginine concentration more effectively than arginine alone.8
A study in humans also showed the citrulline supplementation’s “time release” effect on arginine production. In this study an oral dose of 3.8 grams of citrulline resulted in a 227% peak increase in plasma arginine levels after 4 hours, compared with a 90% peak increase with the same dose of arginine.7,9
Thus, acute oral administration of citrulline appears to be considerably more efficient at raising plasma levels of arginine over the long term than arginine itself.7
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This article is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a physician before embarking on a dietary supplement program.
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Osanai, T; Fujiwara, N; Saitoh, M; Sasaki, S; Tomita, H; Nakamura, M; Osawa, H; Yamabe, H et al. (2002). "Relationship between salt intake, nitric oxide and asymmetric dimethylarginine and its relevance to patients with end-stage renal disease.". Blood purification 20 (5): 466–8. doi:10.1159/000063555. PMID 12207094
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Schwedhelm E, Maas R, Freese R, Jung D, Lukacs Z, Jambrecina A, Spickler W, Schulze F, Boger RH. Pharmacokinetic and pharmacodynamic properties of oral Citrulline and Arginine: impact on nitric oxide metabolism. Br J Clin Pharmacol. 2008 Jan;65(1):51-9. Epub 2007 Jul 27.
Kuhn KP, Harris PA, Cunningham GR, Robbins IM, Summar ML, Christman BW. Oral citrulline effectively elevates plasma arginine levels for 24 h in normal volunteers. Circulation AHA Scientific Sessions 2006; abstract 1692, p. II-1339.
Figueroa A, Trivino JA, Sanchez-Gonzalez MA, Vicil F. Oral Citrulline supplementation attenuates blood pressure response to cold pressor test in young men. Am J Hypertens. 2010 Jan;23(1):12-6. Epub 2009 Oct 22.
Sureda A, Cordova A, Ferrer MD, Tauler P, Perez G, Tur JA, Pons A. Effects of Citrulline oral supplementation on polymorphonuclear neutrophils oxidative burst and nitric oxide production after exercise. Free Radic Res. 2009 Sep;43(9):828-35. Epub 2009 Jul 6.
Chinda D, Nakaji S, Umeda T, Shimoyama T, Kurakake S, Okamura N, Kumae T, Sugawara K. A competitive marathon race decreases neutrophil functions in athletes.Luminescence. 2003 Nov-Dec;18(6):324-9.
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