What it is
L-Citrulline is an amino acid first found in watermelon (the Latin name for watermelon is Citrullus). The HCL form is citrulline bonded to hydrochloride for stability.
What it does in Memoclear
Citrulline does something arginine cannot. When you swallow arginine, the gut and liver break down a large share of it before it reaches the blood. Citrulline mostly skips that breakdown, travels to the kidneys and is converted into arginine there. Studies show oral citrulline raises blood arginine more effectively than oral arginine does. In Memoclear it is the recycling loop that keeps nitric oxide production going after the direct arginine is used up.
Where it comes from in food
Watermelon is the richest food source. Smaller amounts are in cucumber, pumpkin and other melons.
What the research says
The citrulline-to-arginine conversion is well documented, and several trials show citrulline supplements raise plasma arginine and nitric oxide markers. Blood pressure and blood-vessel studies show modest benefits. As with arginine, direct trials on memory in healthy adults are limited.
Who should be careful
Citrulline is generally well tolerated. Because it raises arginine and nitric oxide, the same interaction cautions apply for blood pressure medicine, nitrates and erectile dysfunction medicine.
Where it sits in the formula
L-Citrulline HCL works alongside the other five ingredients: L-Arginine (base), L-Arginine AKG 2:1 Extract, L-Citrulline Malate, Niacin (Vitamin B3), Beta-Alanine. Together they cover blood flow, cell energy and neuron protection in one daily capsule.
Further reading
L-Citrulline and plasma arginine, PubMed. This research is on the ingredient, not on the finished Memoclear product.