Ingredient comparison
L-Arginine vs L-Citrulline: Two Amino Acids, One Capsule
L-arginine vs L-citrulline: both are amino acids studied for blood pressure, in grams a day. Melonex holds citrulline in line 1 (at most 500 mg) and arginine in lines 2 and 3 (at most 333 mg together). Trials used 3-9 g of citrulline and 4-24 g of arginine. No trial tested Melonex.
Written by the Melonex numbers deskUpdated
01The basics
How do L-arginine and L-citrulline differ?
Both are amino acids your body makes and eats in food. Arginine is used directly; citrulline is a related amino acid found in watermelon and supplements.
A common idea is that the body can convert citrulline into arginine, which is why makers put both in one capsule. That idea is a theory about how they might work together. It is not a result from a Melonex trial.
On the label, they are split into three lines. L-citrulline DL-malate is first, L-arginine alpha-ketoglutarate (AKG) second and L-arginine HCl third. Both of the last two are arginine.
So Melonex is one citrulline line and two arginine lines, ordered by weight (21 CFR 101.36 (proprietary blends)).
1 capsule a day
- L-Citrulline DL-Malate≤500 mg
- L-Arginine (Alpha-Ketoglutarate dihydrate)≤250 mg
- L-Arginine HCL≤167 mg
- Whole blend500 mg
- Water
- 8 oz with the capsule
- One bottle lasts
- 60 days
- Label
- The suggested use
2 capsules a day
- L-Citrulline DL-Malate≤1,000 mg
- L-Arginine (Alpha-Ketoglutarate dihydrate)≤500 mg
- L-Arginine HCL≤333 mg
- Whole blend1,000 mg
- Water
- 16 oz with the capsules
- One bottle lasts
- 30 days
- Label
- The most the label allows
Ceilings from the label order (place k holds at most 500/k mg) (21 CFR 101.36 (proprietary blends)). The label: "As a dietary supplement, take one (1) capsule daily with an 8 oz. glass of water. May take up to two (2) capsules daily."
02Side by side
How do citrulline and arginine compare in numbers?
Citrulline trials ran 3-9 g a day and arginine trials 4-24 g a day. A Melonex capsule holds a few hundred milligrams of each at most.
| Measure | L-citrulline | L-arginine |
|---|---|---|
| Trial dose | 3-9 g a day | 4-24 g a day |
| Trials in review | 8, 12-34 people each | 11, 387 people |
| Systolic change | about -4.1 mm Hg | about -5.4 mm Hg |
| Diastolic change | -2.75 at 6 g or more | about -2.7 mm Hg |
| Melonex lines | 1 line | 2 lines |
| 1 capsule, at most | 500 mg | 333 mg together |
| 2 capsules, at most | 1,000 mg | 667 mg together |
| Share of trial low end | 17% of 3 g | 8% of 4 g |
Sources: citrulline review (Avicenna J Phytomed 2019, L-citrulline and BP meta-analysis), arginine reviews (Am Heart J 2011, L-arginine and BP meta-analysis) (Drugs.com, L-arginine monograph). Ceilings come from label order. Weights include the malate, AKG and HCl parts.
03Blood pressure
Is citrulline or arginine better for blood pressure?
The research does not crown a winner. Both showed small drops in pressure at gram doses, in small trials that cannot be compared head to head.
Citrulline or arginine for blood pressure is a fair question, and the honest answer is that no trial pitted them against each other in the reviews we use. The citrulline review found systolic pressure about 4 mm Hg lower. The authors said it may reduce systolic pressure (Avicenna J Phytomed 2019, L-citrulline and BP meta-analysis).
The arginine review found about 5 mm Hg lower systolic and 2.7 lower diastolic (Am Heart J 2011, L-arginine and BP meta-analysis). Different people, different doses, different weeks. A 1 mm Hg gap between two separate reviews is not a ranking.
WebMD calls the citrulline effect small and possibly not clinically meaningful (WebMD, L-citrulline).
These are supplements. The label says they are not intended to diagnose, treat, cure or prevent any disease. Keep taking prescribed medicine and follow your doctor's plan.
04Forms
Which forms does Melonex use?
Melonex uses citrulline bound to malate, arginine bound to alpha-ketoglutarate, and arginine bound to hydrochloride.
The partner molecule adds weight. NIH notes citrulline malate is about 57% citrulline by weight (NIH ODS, Supplements for Exercise). If Melonex follows that ratio, a 500 mg citrulline malate ceiling is about 283 mg of citrulline. The label prints no ratio.
Studies of the AKG form of arginine found little. Before exercise, 3,000 mg did not raise strength in 16 men (J Int Soc Sports Nutr 2012, AAKG). A week of an AAKG product did not raise blood flow in 24 men (Baylor University, AAKG and blood flow).
- Citrulline DL-malate: line 1, at most 500 mg
- Arginine AKG: line 2, at most 250 mg
- Arginine HCl: line 3, at most 167 mg
Profiles: citrulline DL-malate, arginine AKG, arginine HCl.
05Safety
Do citrulline and arginine have the same side effects?
Mostly, yes: an upset stomach leads for both, and both can add to the effect of blood-pressure drugs.
For citrulline, the usual complaint is an upset stomach, and it can interact with blood-pressure medicines, nitrates and erectile-dysfunction drugs (WebMD, L-citrulline). For arginine, add belly pain, bloating, headache and gout, plus a warning against use after a recent heart attack (Mayo Clinic, L-arginine).
In the VINTAGE MI trial, 6 of 153 heart-attack patients died on 9 g of arginine a day, against none on placebo (ACC, VINTAGE MI trial summary). Arginine also raises potassium concerns with some drugs.
Pregnant, nursing, under 18 or living with a medical condition: the label asks you to see a physician first.
06Bottom line
So which one is Melonex?
Melonex is both, in small amounts, with citrulline listed first. It is not a high-dose version of either.
One capsule is 500 mg of blend. Even if citrulline took the whole thing, that is 17% of the low end of the citrulline trials. Arginine is capped at 8% of its low end.
See the bigger picture on claims vs evidence, and the medicine table on side effects and interactions.
07FAQ
Arginine and citrulline questions
Is L-citrulline or L-arginine stronger?
Neither can be called stronger. Reviews found small drops in blood pressure for each at gram doses, in separate groups of small trials. Melonex holds at most 500 mg of citrulline salt and 333 mg of arginine salts.
Does the body turn citrulline into arginine?
That is the usual explanation for pairing them. It is a theory, not a Melonex result. NIH found arginine at 2-20 g did not raise nitric oxide or blood flow in exercise studies (NIH ODS, Supplements for Exercise).
Can I take arginine and citrulline together?
Melonex puts them in one capsule, with the label's one-a-day direction and a two-a-day maximum. If you take blood-pressure drugs, nitrates or ED drugs, ask your pharmacist first.
What is citrulline malate?
Citrulline malate is citrulline bound to malate. NIH says it is about 57% citrulline by weight (NIH ODS, Supplements for Exercise). Melonex lists citrulline DL-malate and prints no ratio.
Which has fewer side effects, citrulline or arginine?
Citrulline has a shorter list: mostly stomach upset (WebMD, L-citrulline). Arginine adds bloating, headache, gout and asthma concerns (Mayo Clinic, L-arginine). Both can interact with blood-pressure medicine.
Is watermelon the same as citrulline?
No. Watermelon contains citrulline, but the Melonex label lists no melon. It lists citrulline DL-malate, a supplement form, not fruit extract.
08Who wrote this
Written and reviewed by
Pages built from the label, the seller's materials and linked NIH, FDA, CDC, AHA, FTC and peer-reviewed sources.
Last updated . Read how we write and how we check reviews. This website is run by Melonexheart, which describes itself as a U.S. authorized Melonex merchant. It is not the manufacturer or the label's distributor, and we cannot independently verify the 'authorized' status. We are paid when you buy through our order links.
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