About the Product
Marvelous Nutrition's Arginine is a pure L-Arginine powder supplement from the Old School line, with 4000mg of L-Arginine per serving — the semi-essential amino acid central to the production of nitric oxide (NO), growth hormone (GH) secretion, endogenous creatine synthesis, and ammonia detoxification via the urea cycle. Free Form. Premium Quality. 100% Pure. Vegan. GMP. Gluten Free. 75 servings, 388g. Marvelous's own website recommends mixing Arginine with their pre-workout Experiment to boost the pump.
Ingredient: L-Arginine (100% pure, free form). No other ingredients.
Benefits
L-Arginine: the direct substrate of nitric oxide synthase (NOS) and the center of nitrogen metabolism:
L-Arginine (2-amino-5-guanidinopentanoic acid) is a semi-essential amino acid (essential under conditions of stress, disease, or accelerated growth, but endogenously synthesizable under normal conditions) with a central role in multiple metabolic pathways. Its most relevant function for athletic performance is as an obligatory substrate of nitric oxide synthase (NOS) — the enzyme that converts L-Arginine + O₂ into L-Citrulline + NO (nitric oxide). The NO produced in the endothelial cells of blood vessels diffuses into the adjacent vascular smooth muscle, where it activates soluble guanylate cyclase (sGC) to produce cGMP (cyclic guanosine monophosphate), which activates protein kinase G (PKG) and induces vascular smooth muscle relaxation — i.e., vasodilation. This vasodilation increases muscular blood flow, oxygen and nutrient delivery, and produces the characteristic muscle pump sought by strength athletes.
The hepatic first-pass limitation of oral arginine and why citrulline is complementary:
An important technical aspect about oral L-Arginine: oral free L-Arginine has intestinal absorption partially limited by hepatic and intestinal first-pass metabolism — arginine is converted to ornithine + urea by hepatic arginase before reaching systemic circulation, reducing plasma bioavailability compared to the ingested dose. This is why L-Citrulline (which avoids intestinal and hepatic arginase by being metabolized differently, being converted to arginine in the kidneys) is often more effective than oral arginine in increasing plasma arginine levels. However, the combination of L-Arginine + L-Citrulline is superior to each one alone: citrulline ensures the sustained increase in plasma arginine long-term, and pure arginine ensures a faster onset via immediate NOS saturation. The Marvelous website explicitly recommends mixing standalone Arginine with Experiment to potentiate this combined effect.
GH (Growth Hormone) secretion: the endocrine effect of arginine:
L-Arginine stimulates the secretion of growth hormone (GH) by the anterior pituitary via inhibition of somatostatin (the hypothalamic inhibitor of GH release) and by direct stimulation of somatotrophic cells. This effect is more pronounced with intravenous arginine infusion (used clinically as a GH reserve stimulation test) than with oral supplementation, but studies with oral doses of 5 to 9g/day have documented GH increases of 100 to 300% above baseline at rest, especially when fasting. GH stimulates lipolysis (fat mobilization from adipocytes), muscle protein synthesis, and IGF-1 (insulin-like growth factor 1, the central anabolic mediator of GH) synthesis. For pre-workout use, arginine potentiates the GH secretion that naturally accompanies high-intensity exercise, potentially amplifying the hormonal response to training.
Endogenous creatine synthesis and ammonia detoxification:
In addition to NO and GH, L-Arginine participates in two other metabolic pathways relevant to athletes. It is the guanidino group donor in creatine synthesis (via AGAT: arginine + glycine → guanidinoacetate + ornithine, followed by methylation by GAMT to creatine), supporting the replenishment of intramuscular creatine stores. It is also an intermediary of the urea cycle (arginine → ornithine + urea via arginase, with elimination of toxic nitrogen in the form of urea excreted in the urine), contributing to the elimination of ammonia produced by muscle catabolism during intense exercise.
4000mg per serving: the documented therapeutic dose for performance effects:
The dose of 4000mg (4g) per serving is within the documented window in clinical studies on oral arginine and performance: doses of 3 to 6g/day are associated with increases in NO, vasodilation, and improved muscle pump; doses of 5 to 9g/day with GH stimulation; doses of 6 to 8g/day with improved exercise capacity in athletes with cardiovascular disease. The 4g dose is therefore a moderate and safe dose, suitable for standalone use or in a stack with citrulline (for combined vasodilatory effect) or with Experiment/INFECTED (for maximum pump).
Free Form, 100% Pure, GMP: the premium quality of Marvelous Arginine:
The designation Free Form confirms that the L-Arginine in the product is in the free amino acid form — without salts (such as hydrochloride or alpha-ketoglutarate which alter molecular weight and reduce the percentage of arginine per gram of product). 100% Pure confirms the absence of any additives, fillers, or excipients. GMP (Good Manufacturing Practices) certification ensures that the product is manufactured in facilities with the highest standards of quality control, hygiene, and traceability. Vegan confirms its plant-based origin by fermentation (without any animal ingredients). Gluten Free confirms the absence of gluten contamination.
Usage
Recommended dosage: Dissolve 4g (check included scoop) in 250 to 400ml of cold water, 30 minutes before training. For maximum pump, mix directly into the shaker with Experiment or INFECTED pre-workout (as officially recommended by the Marvelous website). For NO stack use without a stimulant pre-workout, combine 4g of Arginine + 5g of Glycerol in the same glass of water 30 minutes before training. For GH stimulation while fasting, consume 4 to 6g of arginine on an empty stomach (30 minutes before breakfast or before morning fasted training), away from protein-rich meals (which suppress GH secretion). 75 servings, 388g.
