L-Citrulline / Citrulline Malate

Evidence: ★★★★☆ · Status: OTC Supplement

In plain English

It widens your blood vessels so more blood, oxygen, and nutrients reach working muscle — that's the "pump," plus real endurance and lower blood pressure.

How it works

Converts to arginine → nitric oxide via endothelial NOS3 (eNOS), causing vasodilation, better O₂ delivery, and reduced ammonia. More effective than oral arginine (which is destroyed first-pass).

Molecular target & official sources

NOS3 endothelial nitric oxide synthase (NCBI Gene) · L-Citrulline (PubChem CID 9750)

Protocol

6–8 g L-citrulline (or 8–12 g citrulline malate) 60 min pre-workout.

Bottom line

Better-studied than most pre-workout ingredients.

Helps with: Build Muscle & Strength · Endurance · Cardiovascular

Stacks with

Shares a pathway — often paired with: Caffeine, PDE-5 Inhibitors (Sildenafil / Tadalafil), Minoxidil, Caffeine (thermogenic).

Avoid combining with

Stacking strong blood-flow agents — citrulline + beetroot + ED drugs (PDE-5) + nitrates together can drop blood pressure dangerously.

Availability & where to buy

Available over the counter. Widely available OTC — e.g. iHerb (ships worldwide); in Singapore also Guardian, Watsons, GNC, Shopee / Lazada. Look for a third-party-tested / GMP mark and check the dose per serving. ~S$20–35/month; citrulline malate is dosed higher than pure citrulline (check which you have).

How it works: the Nitric oxide / cGMP pathway →

Used in these protocols

• High Blood Pressure
• Low Libido
• Pre-Workout Energy

Compare L-Citrulline / Citrulline Malate

• L-Citrulline / Citrulline Malate vs Caffeine
• L-Citrulline / Citrulline Malate vs EPO (Erythropoietin)
• L-Citrulline / Citrulline Malate vs Beta-Alanine
• L-Citrulline / Citrulline Malate vs Sodium Bicarbonate
• L-Citrulline / Citrulline Malate vs Beetroot / Dietary Nitrate
• L-Citrulline / Citrulline Malate vs Iron
• L-Citrulline / Citrulline Malate vs Taurine
• L-Citrulline / Citrulline Malate vs Omega-3 (EPA/DHA)