Ingredient profile
L-Arginine Alpha-Ketoglutarate in Melonex: The Second Line
L-arginine alpha-ketoglutarate, often called arginine AKG, is the second ingredient in the Melonex blend, so one capsule holds at most 250 mg of it. Blood pressure trials of L-arginine used 4 to 24 g a day. It is not advised after a recent heart attack. No trial has tested Melonex.
Written by the Melonexcare editorsUpdated
No. 01What it is
What is L-arginine alpha-ketoglutarate?
L-arginine alpha-ketoglutarate is the amino acid L-arginine paired with alpha-ketoglutarate, a compound the body makes. Melonex lists it second, as a dihydrate.
On the label it reads "L-Arginine (Alpha-Ketoglutarate dihydrate)." Dihydrate means each unit of the salt carries two water molecules. They add weight but no nutrient.
Arginine is an amino acid in meat, dairy and nuts. Your body uses it to make nitric oxide, a gas that helps blood vessels relax. Alpha-ketoglutarate, or AKG, takes part in how cells burn fuel.
The AKG half is only the partner in this salt. A drug reference notes that its "possibly effective" uses are for IV use in hospitals, and that evidence for oral use is not enough (RxList, alpha-ketoglutarate).
| Name on the label | L-Arginine (Alpha-Ketoglutarate dihydrate) |
|---|---|
| What it is | L-arginine (an amino acid) paired with alpha-ketoglutarate |
| Place on the label | 2nd of 3 in the 500 mg proprietary blend |
| Amount per capsule | Not listed; #2 of 3 in the 500 mg blend, so at most 250 mg per capsule |
| At the label maximum (2 capsules) | at most 500 mg |
| Amount used in research | 4-24 g a day of L-arginine in blood pressure trials |
| Strength of evidence | Small drops in blood pressure in trials of grams a day; no trial of Melonex |
| Role | Amino acid used to make nitric oxide |
| Main caution | Not recommended after a recent heart attack; may drop pressure too low with nitrates, sildenafil or blood pressure drugs. |
No. 02How much
How much arginine AKG is in a Melonex capsule?
At most 250 mg per capsule. The second name in a 500 mg blend cannot weigh more than half of it, and the real figure is not printed.
The label lists the blend from most to least by weight (21 CFR 101.36). If the first line took 250 mg, the second could match it. If the first took more, the second would have to be smaller.
An even split would put it near 167 mg. At two capsules a day, the ceiling is 500 mg of the salt.
The bar shows the salt, not the arginine inside it. The free amino acid is less.
No. 03The studies
What do trials of L-arginine and blood pressure show?
In 11 trials with 387 people, oral L-arginine at 4 to 24 g a day went with a small drop in blood pressure compared with placebo.
The average difference was about 5.39 mm Hg systolic and 2.66 mm Hg diastolic (Dong 2011, arginine and BP). That is small, and it came from grams a day, not hundreds of milligrams.
Other reviews are more cautious. One consumer drug guide says arginine "may provide small improvements" and may not be enough to manage high blood pressure (WebMD, L-arginine).
| Measure | Amount per day |
|---|---|
| Lowest dose in the 11 trials | 4,000 mg |
| Highest dose in the 11 trials | 24,000 mg |
| Melonex at 1 capsule, ceiling of this line | 250 mg |
| Melonex at 2 capsules, ceiling of this line | 500 mg |
No. 04After a heart attack
Is L-arginine safe after a heart attack?
After a recent heart attack, it is not recommended. In one trial, arginine at 9 g a day was stopped early after more deaths than on placebo.
The VINTAGE MI trial enrolled 153 adults after a first heart attack. Six died on arginine, 8.6 percent, and none on placebo. The safety board ended the trial early (VINTAGE MI trial (ACC summary)).
The dose, 9 g a day, was far above one capsule. Even so, a major clinic advises against arginine after a recent attack (Mayo Clinic, L-arginine). If you have had one, ask your cardiologist before you open the bottle.
No. 05Blood pressure
Does L-arginine lower blood pressure?
In trials at grams a day, it went with a small drop. What it does in a 250 mg share of a capsule has not been tested.
People search for "l-arginine blood pressure" hoping for a yes or no. The honest answer is a range: small drops in trials, at large doses, in short studies.
The same effect is why a medicine list matters. Arginine can add to blood pressure drugs, nitrates and sildenafil, and pressure may drop too low (Mayo Clinic, L-arginine). Signs include dizziness on standing.
Do not stop or change a heart or blood pressure medicine because you started a supplement. Tell your pharmacist about the capsule.
No. 06Tolerance
What are the side effects of L-arginine?
At large doses, the common ones are stomach upset, bloating, nausea and diarrhea. One capsule holds far less than those doses.
The NIH says up to 9 g a day for weeks was well tolerated, and that 9 to 30 g a day often caused stomach upset and slightly lower pressure. Safety beyond three months is not known (NIH ODS, arginine and citrulline).
Other reported effects include abdominal pain, headache, gout and worse asthma (Mayo Clinic, L-arginine). For arginine and potassium, see the arginine HCl profile.
No. 07Keep reading
Where should you read next?
The third line is a second form of arginine, so its cautions overlap with this one.
Read the arginine HCl profile, then the supplement facts. If you decide to order, see pricing.
No. 08FAQ
L-arginine AKG questions
What is L-arginine alpha-ketoglutarate?
L-arginine alpha-ketoglutarate is the amino acid arginine paired with alpha-ketoglutarate, a compound the body makes. In Melonex it is listed second, as a dihydrate, inside a 500 mg proprietary blend.
What is arginine AKG used for?
Supplement makers sell it for exercise and heart support. Evidence is limited: the AKG part has proven uses only by IV in hospitals (RxList, alpha-ketoglutarate), and arginine's blood pressure effects are small. The Melonex label makes no medical claim.
How much arginine AKG is in Melonex?
The label does not say. As the second name in a 500 mg blend, it can be at most 250 mg per capsule. An even split among three lines would be about 167 mg, and the arginine itself is less.
Does L-arginine lower blood pressure?
In 11 trials, arginine at 4 to 24 g a day went with systolic pressure about 5 mm Hg lower than placebo (Dong 2011, arginine and BP). One Melonex capsule holds far less, and the product itself has never been tested.
Can I take arginine after a heart attack?
Not without your cardiologist. In a trial after heart attacks, 6 people died on arginine and none on placebo, and it was stopped early (VINTAGE MI trial (ACC summary)). A major clinic advises against arginine after a recent attack (Mayo Clinic, L-arginine).
Is arginine safe with blood pressure medicine?
Ask your doctor or pharmacist first. Arginine can add to blood pressure drugs, nitrates and sildenafil, and push pressure too low (Mayo Clinic, L-arginine). Keep taking your prescribed medicine exactly as directed.
Is Melonex the same as an arginine AKG supplement?
Not quite. Melonex pairs arginine AKG with citrulline malate and arginine HCl in one 500 mg blend. Its amounts are hidden, so it is not comparable to a single-ingredient product with a printed dose.
No. 09Who wrote this
Written and reviewed by
Pages built from the bottle label, the seller’s order page and linked NIH, FDA, CDC, AHA, FTC and peer-reviewed sources.
Last updated . Learn about our editorial standards and how we check reviews. This website is run by Melonexcare, which describes itself as an authorized American Melonex outlet. It is not the manufacturer or the label’s distributor. Buying through our order links earns us money.
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