What is citrulline malate?
Citrulline malate is a compound combining L-citrulline — a non-essential amino acid — with malate, a salt of malic acid. L-citrulline is found naturally in watermelon. As a supplement it is used primarily for its role in nitric oxide production and the urea cycle.
How it works
L-citrulline is converted to L-arginine in the kidneys, which is then used to produce nitric oxide. Nitric oxide causes vasodilation — widening of blood vessels — which increases blood flow to working muscles. This produces the "pump" effect during training and also improves oxygen and nutrient delivery to muscle tissue. Malate supports the Krebs cycle, contributing to energy production and reduced fatigue.
What the research says
- 8g of citrulline malate significantly reduced muscle soreness and improved performance in a bench press protocol (Pérez-Guisado & Jakeman, 2010)
- Increases repetition volume in upper and lower body resistance exercise
- Improves aerobic performance and reduces perceived effort during endurance exercise
- More effective at raising plasma arginine levels than direct L-arginine supplementation
Effective dose
6–8g of citrulline malate (2:1 ratio) taken 30–60 minutes before training. Products listing "L-citrulline" rather than "citrulline malate" require a lower dose — 3–6g — as there is no malate component by weight. Many pre-workout supplements underdose citrulline at 2–3g — below the threshold shown to produce meaningful effects in research.
What to check on the label
Check whether the product lists citrulline malate or L-citrulline — these are different. Citrulline malate at 2:1 ratio means roughly 67% citrulline by weight. A product listing 4g of citrulline malate contains approximately 2.7g of actual citrulline — below the effective dose. Look for 6g minimum of citrulline malate or 3g minimum of L-citrulline.
Proprietary blends that do not disclose individual ingredient doses make it impossible to assess whether citrulline is present at an effective level.
Safety
Well tolerated at recommended doses. No established adverse effects in healthy adults. May cause mild gastrointestinal discomfort at high doses in some individuals.