L-Citrulline is the surprising powerhouse of nitric oxide pathway support - often raising arginine levels better than arginine itself. Here's how it works, what the research shows, and why it pairs with arginine in formulas like Memocept.
L-Citrulline is a non-essential amino acid found naturally in watermelon and produced by the body. Its name comes from Citrullus, the Latin for watermelon. While it isn't used to build protein, it plays a key role in the urea cycle and, importantly for circulation, in nitric oxide production. Memocept includes two forms: L-Citrulline HCL and L-Citrulline Malate (citrulline bound to malic acid, which adds energy-metabolism support).
Here's the counterintuitive part: L-citrulline is often more effective at raising blood arginine levels than taking L-arginine directly. When you take L-arginine orally, much of it’s broken down in the gut and liver before reaching the bloodstream. L-citrulline bypasses this - it's absorbed efficiently and then converted to arginine in the kidneys, leading to a more sustained rise in arginine and nitric oxide. This is why the two are so often combined: arginine provides an immediate source, citrulline sustains it (PMID 28336910).
By raising arginine and supporting nitric oxide, L-citrulline supports vasodilation - the widening of blood vessels - and healthy blood flow. For the brain, the relevance is the same as arginine's: better circulation supports the delivery of oxygen and nutrients to neurons. Citrulline is also part of the brain's own citrulline-NO cycle, the recycling system that regenerates arginine from the citrulline produced during nitric oxide synthesis.
Citrulline supplementation has been studied extensively for vascular function and exercise performance. Reviews find it supports nitric oxide production and vascular function (PMID 28336910), and systematic reviews have examined its effects on circulation and performance (PMID 32824588). A narrative review of arginine and citrulline confirms their combined role in cardiovascular health (PMID 36014985). As with arginine, most research targets cardiovascular and exercise outcomes; the cognitive benefit is inferred from improved blood flow to the brain rather than from direct memory trials.
Research on citrulline for circulation often uses several grams per day (commonly 3-6g of citrulline malate). Supplement cognitive formulas like Memocept use smaller amounts (100mg each of HCL and Malate forms), so the effect is gentler. Citrulline malate adds malic acid, which is involved in the body's energy cycle, while citrulline HCL is a more concentrated form. Using both offers complementary delivery.
L-Citrulline is generally well tolerated, with occasional mild digestive upset. Like arginine, it lowers blood pressure through vasodilation, so anyone on blood pressure or heart medication, or with low blood pressure, should consult a doctor before use. The same caution applies to combining it with erectile dysfunction medications, which share the nitric-oxide mechanism.
Memocept pairs two forms of L-Citrulline with two forms of L-Arginine - a deliberate strategy to support nitric oxide from multiple angles and sustain the effect longer. Together they form the circulation backbone of the formula, complemented by Niacin for energy and Beta-Alanine for endurance. It's a thoughtfully constructed nitric-oxide blend, with the usual blood-pressure caution applying to the combination.
Gonzales JU, et al. (2017) "Citrulline supplementation, vascular function, and exercise." Nutr Res. PMID: 28336910
Viribay A, et al. (2020) "Effects of citrulline supplementation on exercise performance: a systematic review." Nutrients. PMID: 32824588
Khalaf D, et al. (2022) "Dietary arginine and citrulline supplements for cardiovascular health and athletic performance: a narrative review." Nutrients. PMID: 36014985
Citations refer to research on the individual ingredients, not on the Memocept product itself. Studies often use doses, delivery methods, or populations that may differ from those in the product. Memocept is a dietary supplement; these statements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease.
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