Melonex Ingredients: The 500 mg Blend, Form by Form, With the Research

The whole formula in one table

Melonex has three active ingredients and three inactive ones. That makes it one of the shortest labels in the blood pressure supplement category, which is a point in its favor: there is nothing hidden among dozens of botanicals. The weakness is elsewhere. All three actives sit inside a single 500 mg "proprietary blend", so the label tells you what is in the capsule but not how much of each.

The ingredient order inside a blend follows weight, from most to least. Citrulline malate comes first, so it is most likely the largest share. That is a sensible choice pharmacologically, as the sections below explain, but the label still leaves the actual numbers unknown.

Three framing points apply to everything on this page. First, all three ingredients act through one pathway, nitric oxide, so the formula is less of a "combination" than its three names suggest. Second, the research on that pathway was done with grams, not milligrams. Third, none of the studies below tested Melonex itself; they tested its ingredients, usually alone.

L-Citrulline DL-malate

What it is

L-citrulline is an amino acid that the body does not use to build proteins. Instead it shuttles nitrogen: cells in the small intestine make citrulline, release it into the blood, and the kidneys convert it into arginine, which then circulates to tissues. Inside blood vessel cells, the same conversion happens locally, recycling the citrulline left over each time nitric oxide is made. Watermelon, especially its pale rind, is the richest common food source, and the name itself comes from Citrullus, the watermelon genus.

"Citrulline malate" is citrulline bonded to malic acid. Commercial citrulline malate is usually sold as 2:1 (two parts citrulline to one part malate) or 1:1. The Melonex label does not say which, and "DL-malate" means the malic acid is a mix of its two mirror-image forms, which is the cheaper industrial version. The citrulline itself is the natural L form.

Why citrulline is the smarter half of the formula

When you swallow arginine, enzymes called arginases in the gut wall and liver break down a large share of it before it reaches the circulation. Citrulline is not a substrate for those enzymes. In a randomized crossover study in 20 healthy volunteers, oral citrulline raised plasma arginine in a dose-dependent way and did so more effectively than oral arginine, while also increasing markers of nitric oxide activity such as urinary nitrate and cyclic GMP^[1]. Reviews of citrulline for heart and metabolic health reach the same conclusion: as a way of raising arginine, citrulline is the better route^[7][8].

What the human research found

The Citrudose study gave healthy men single doses of 2, 5, 10 and 15 grams. All were well tolerated, without the digestive upset that limits arginine, and plasma arginine rose with dose^[2]. In exercise research, 8 grams of citrulline malate taken an hour before training let men complete more repetitions and reduced soreness afterwards^[3], and 6 grams a day for a week improved how quickly the body ramped up oxygen use at the start of exercise^[4].

For blood pressure the data are thinner. A pilot study gave nine people with prehypertension a watermelon extract that supplied about 2.7 grams of citrulline and 1.3 grams of arginine a day, and found lower aortic systolic pressure and wave reflection after six weeks^[5]. A 2019 meta-analysis pooled the small citrulline trials and reported a reduction in systolic pressure; the authors noted short durations and small samples^[6].

How the Melonex amount compares

Unknown, because of the blend. The ceiling is clear, though: if the entire 500 mg were citrulline malate in a 2:1 ratio, one capsule would hold about 330 mg of citrulline, and the label maximum of two capsules about 670 mg. Blood pressure and vascular studies typically used 3 to 6 grams, so the best case is roughly a tenth to a fifth of the research range.

L-Arginine alpha-ketoglutarate (dihydrate)

What it is

Arginine alpha-ketoglutarate, usually shortened to AAKG, is a salt of arginine with alpha-ketoglutarate. AKG is an intermediate in the Krebs cycle, the series of reactions cells use to release energy from food, and it also takes part in amino-acid metabolism. In supplements, the pairing is popular mainly because AAKG became a staple of bodybuilding "pump" products in the 2000s. "Dihydrate" means each unit of the crystal carries two water molecules, which adds weight without adding anything active.

What the human research found

The most-cited trial gave 35 resistance-trained men 12 grams of AAKG a day, in three doses, for eight weeks. It was well tolerated and safe on blood tests, and the AAKG group improved one-repetition bench press and sprint peak power slightly more than placebo; it did not change body composition or aerobic capacity^[9]. That study measured strength and power, not blood pressure or blood vessel function, and it used about twenty-four times the entire Melonex blend.

No published trial has tested AAKG for blood pressure. Its relevance to Melonex rests on the fact that it delivers arginine, so the arginine evidence below is what applies.

How the Melonex amount compares

Roughly half of AAKG's weight is arginine. If, say, a third of the blend were AAKG, a capsule would supply under 100 mg of arginine from this source. The sales page describes AAKG as "highly-tolerated" and gentle on the stomach; at this size of dose that is true of almost anything.

L-Arginine HCl

What it is

Arginine is one of the twenty amino acids used to build proteins, and the one that nitric oxide synthase uses to make nitric oxide. The body makes some itself, mostly from citrulline, and gets the rest from food: meat, poultry, fish, dairy, nuts, seeds and legumes are all good sources. A typical Western diet supplies several grams a day^[13]. Arginine HCl is the hydrochloride salt, stable and inexpensive, and about 83% arginine by weight.

What the human research found

A 2011 meta-analysis pooled 11 randomized, double-blind, placebo-controlled trials with 387 participants. Oral arginine at 4 to 24 grams a day lowered systolic blood pressure by about 5.4 mmHg and diastolic by about 2.7 mmHg compared with placebo^[10]. An umbrella review of meta-analyses found consistent support for modest blood pressure reductions and improved endothelial function, the ability of vessel linings to relax^[11]. Researchers still debate why extra arginine works at all when the enzyme is normally saturated with it, the so-called "arginine paradox"; competition from a natural inhibitor, ADMA, is one leading explanation^[12].

The trial that matters most for safety

VINTAGE MI randomized 153 patients after a heart attack to arginine (3 grams three times a day) or placebo for six months. Arginine did not improve arterial stiffness or heart function, and six patients in the arginine group died compared with none on placebo, so the safety board stopped the trial early^[15]. The doses were far higher than Melonex's, and the deaths may have been chance, but the result is the reason anyone with heart disease should involve a cardiologist before taking arginine in any amount.

How the Melonex amount compares

Even if the entire blend were arginine HCl, one capsule would provide about 415 mg of arginine and two capsules about 830 mg. The blood pressure trials used 4,000 to 24,000 mg a day. Next to the several grams already in a normal diet, one capsule adds a modest top-up.

Why the blend matters more than any single ingredient

A proprietary blend is legal: U.S. rules let a company list a blend's total weight and its ingredients in descending order without giving individual amounts. Companies defend blends as protection for their recipe. For buyers, the cost is that you cannot compare the product with research or with competitors.

Melonex shows why this matters. A 500 mg blend split 400/50/50 between citrulline malate, AAKG and arginine HCl is a very different product from one split 100/200/200, yet both would print the same label. The sales page gives each ingredient its own paragraph of benefits ("primary fuel for nitric oxide", "drastic reduction in strain", "immediate relief"), which implies each is present in a meaningful amount. The label cannot confirm that.

Assumes 2:1 citrulline malate, AAKG at about 50% arginine and arginine HCl at about 83%. Illustrative only; the real split is not published.

What you can say with confidence: whatever the split, one capsule supplies well under half a gram of the amino acids themselves. If you want the maker to settle it, ask [email protected] for the amount of each blend ingredient per capsule or for the certificate of analysis for your lot.

The inactive ingredients

Hydroxypropyl methylcellulose (HPMC) is the capsule shell, made from plant cellulose. It suits vegetarians and vegans, though the label does not make a vegan claim. Microcrystalline cellulose is purified wood or cotton fiber used as a filler so that each capsule fills to the same weight. Magnesium stearate is a common flow agent in very small amounts; online claims that it blocks absorption are not supported by evidence.

No colors, sugars, sweeteners, gluten sources, soy, dairy or shellfish are listed. The label does not carry an allergen statement, which is consistent with none of the major allergens being present, but it also makes no "free from" claims. If you have a severe allergy, confirm with the maker.

What is not in Melonex

It is useful to know what a blood pressure supplement does not contain, because the category is crowded with ingredients that have different evidence. Melonex has none of the following:

• Dietary nitrate (beetroot juice or extract), the other main route to nitric oxide, studied in hundreds of milligrams of nitrate a day.
• Potassium, which helps offset the effect of sodium on blood pressure and is part of the DASH eating pattern.
• Magnesium at a meaningful dose (the stearate is a trace flow agent).
• Hibiscus, garlic, hawthorn, olive leaf or CoQ10, botanicals and nutrients with their own small blood pressure literatures.
• Stimulants such as caffeine or yohimbe, which is a plus for a blood pressure product.

This is not a criticism in itself; a focused formula is easier to evaluate. It does mean Melonex's case rests entirely on the citrulline and arginine evidence, and therefore on the dose question.

Ingredient safety in one place

At the amounts in Melonex, citrulline and arginine are well within normal dietary exposure. Arginine's classic side effects, nausea, cramps, bloating and diarrhea, appear at single doses of several grams^[14]; citrulline is better tolerated even at high doses^[2]. The interactions to take seriously are pharmacological rather than dose-related: nitrates and PDE5 inhibitors such as sildenafil already act on the nitric oxide pathway and must not be combined with each other^[16], blood pressure medicines can add to any lowering effect, and arginine after a heart attack has the VINTAGE MI result against it^[15]. As with any supplement, the company, not the FDA, is responsible for safety before sale^[17]. The safety page covers each point in depth.

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