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L-Citrulline vs L-Arginine: How the Two Relate
L-citrulline is partly converted into L-arginine in the body, and arginine feeds nitric oxide production. One study found citrulline raised blood arginine more than arginine itself did, because arginine is broken down in the gut. Trial results for both are small and mixed, and Melonex contains both.
Written by the Melonex label deskUpdated · 4 min read
How is citrulline related to arginine?
Citrulline is a building block the body converts into arginine, which in turn makes nitric oxide 1.
So the two sit on the same path. Arginine is closer to the end, citrulline is closer to the start. Nitric oxide is a gas the lining of blood vessels makes, and it helps widen them.
That shared path is why a product can list both without repeating itself. It is also why a claim about one cannot simply be copied to the other. Each was tested separately, in different groups, at different doses, so line up the numbers before you compare.
Which one does the body absorb better?
Citrulline, in the one study that compared them. Oral arginine is largely broken down in the gut before it reaches the blood 2.
L-Citrulline
Readily absorbed and partly turned into arginine. In 20 healthy volunteers it raised blood arginine more than arginine did 2.
L-Arginine
Hampered by intestinal breakdown, so less reaches the blood from a given swallowed amount 2.
Absorption into the blood is not the same as a health result. The same study found that no treatment improved flow-mediated vasodilation over baseline 2. Keep lab numbers and real outcomes apart.
What did the trials find?
Small average changes in blood pressure from each, and wide disagreement between analyses.
| Supplement | Analysis | Systolic change |
|---|---|---|
| L-arginine | 22 trials 3 | -6.40 mm Hg on average |
| L-citrulline | 8 trials 4 | -4.10 mm Hg on average |
| L-citrulline | 5 interventions | No significant change |
One analysis of middle-aged and older adults found the pair together did better than either alone. All of these used grams, not a 500 mg blend.
Melonex: from $49 a bottle60 capsules · 2, 3 or 6 bottles · free US shipping on 3 and 6 · 60-day money-back guarantee
See packsWhat does that mean for one capsule?
Melonex holds both, but the doses in trials dwarf what one capsule can contain.
Label vs studies
Read the blend page to see why amounts matter. A blend label can hide whether the citrulline or the arginine does most of the work, and a shopper cannot compare it with a trial dose without the numbers.
Both amino acids are real, both are studied, and both show small, mixed results at gram doses. A 500 mg three-name blend sits outside that evidence.
So which one wins?
Neither, as a buying reason. The label hides how much of each you get.
If you take blood pressure medicine, nitrates or sildenafil, ask a pharmacist about arginine first, and keep taking what you were prescribed. The ingredients page lists all three names.
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Order 6 bottlesPrices on the Melonex sales page, October 30, 2026 5. Two bottles are also sold for $158, plus $9.99 shipping. Check your medicines with your doctor or pharmacist before you order.
FAQ01
Melonex questions people ask
Is citrulline better than arginine?
In one absorption study, citrulline raised blood arginine more than arginine did. That is a lab finding, not a health result.
Does the body turn citrulline into arginine?
Yes, in part. A clinic page explains citrulline is converted into arginine, which makes nitric oxide.
Why take both in one capsule?
The label does not say. A pooled analysis found the pair did better than either alone in older adults, but it tested grams, not this blend.
Which has more side effects?
Both list bloating and diarrhea. Arginine has more drug interaction warnings than citrulline.
Who wrote this02
Written and reviewed by
Pages built from the label, the sales page and linked NIH, FDA, CDC, FTC and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is the information site for a USA Authorized Melonex Retailer. It is not the manufacturer or the distributor named on the label. We earn money when you buy through our order links.
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