L-Citrulline & L-Arginine Stack

Oxygen delivery to working muscle is a performance ceiling in every distance event; this L-citrulline and L-arginine stack supports nitric oxide production to raise that ceiling at the vascular level.

L-citrulline converts to L-arginine in the kidneys via the citrulline-arginine cycle, raising plasma arginine concentrations more effectively than direct arginine supplementation alone, because citrulline bypasses first-pass liver metabolism where absorbed arginine is largely broken down before reaching circulation. The combined citrulline-arginine stack drives endothelial nitric oxide synthase activity, widening blood vessels and improving oxygen and nutrient delivery to contracting muscle during sustained aerobic effort. L-arginine alpha-ketoglutarate contributes a secondary arginine source alongside a Krebs cycle intermediate that may support ammonia clearance during prolonged training loads.

Built for distance runners, trail runners on sustained climbs, and athletes in structured speed or threshold blocks where blood flow efficiency and oxygen delivery are primary performance constraints. Relevant for any runner looking to build a science-backed pre-race nitric oxide protocol alongside a dietary nitrate source such as beetroot.

Quality and simplicity are at the core of this supplement. Each serving contains carefully measured amounts of active ingredients without unnecessary additives. Add it to your regimen as a reliable way to support your body’s natural performance processes.*

Ingredients: L-Citrulline DL-Malate (400 mg), L-Arginine Hydrochloride (350 mg), L-Arginine Alpha-Ketoglutarate (50 mg), Vegetable Cellulose (Capsule), Brown Rice Flour.

Manufacturer's country: USA

Product amount (oz/lbs/g): 60 capsules / 2.5 oz / 0.15 lbs / 70 g

Gross weight (oz/lbs/g): 2.4 oz / 0.15 lbs / 68 g

Suggested use: As a dietary supplement adults take two (2) capsules daily. For best results, take with 6-8 oz (177-237ml) of water or as directed by healthcare professional.

Warning: Do not exceed recommended dose. Pregnant or nursing mothers, children under the age of 18, and individuals with a known medical condition should consult a physician before using this or any dietary supplement.

KEEP OUT OF REACH OF CHILDREN. DO NOT USE IF SAFETY SEAL IS DAMAGED OR MISSING. STORE IN A COOL, DRY PLACE.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

FAQ

Q: How does the citrulline-arginine combination differ from taking arginine alone?

A: L-citrulline is more effective at raising plasma arginine than direct L-arginine supplementation. When you consume arginine orally, a significant portion is broken down by the liver before reaching systemic circulation. L-citrulline bypasses this first-pass metabolism, converts to arginine in the kidneys, and delivers a more reliable elevation in plasma arginine. Combining both compounds in one formula provides dual-pathway coverage for runners who want consistent nitric oxide support across a session.

Q: How much L-citrulline do runners need, and does this dose deliver that?

A: Performance research on L-citrulline typically uses 4 to 8g of citrulline malate taken acutely before exercise. This formula provides 400mg per 2-capsule serving, which is below that acute performance dose range. At the current serving size, this product is best positioned as a daily nitric oxide support supplement rather than a standalone high-dose pre-race acute intervention. Runners seeking an acute pre-race nitric oxide load should also incorporate dietary nitrate via beetroot alongside this stack.

Q: Is this stack useful for trail runners, not just road runners?

A: Trail running places high demands on blood flow efficiency, particularly on sustained climbs where oxygen delivery to working muscle becomes a direct constraint on pace. The citrulline-arginine nitric oxide mechanism is relevant in exactly this context. Runners who include hill repeats, vertical kilometre efforts, or technical terrain with significant elevation gain are the primary performance use case for this ingredient combination. The daily capsule format supports consistent intake across a training week regardless of where sessions take place.

Q: Can I take this alongside a beetroot supplement?

A: Yes, and this is the recommended approach. Beetroot provides dietary nitrate (NO3), which converts to nitrite (NO2) and then to nitric oxide via a bacteria-dependent pathway in the mouth and gut, a route that does not require arginine or NO synthase. Citrulline and arginine activate the separate enzymatic NO synthase pathway. Using both targets two independent NO production routes simultaneously, making the pre-race stack more robust than either ingredient category alone.