L-Citrulline: Benefits, Dosing, and What the Evidence Shows
L-citrulline is an amino acid popular in pre workout formulas, usually for its role in supporting blood flow and exercise performance. It is often sold as plain L-citrulline or as citrulline malate, which pairs it with malic acid.
Here is what the research actually supports, the doses used in studies, and how it stacks up against arginine.
Key takeaways
- L-citrulline raises nitric oxide precursors in the body, which supports blood vessel widening and blood flow.
- Studies use roughly 6 to 8 grams of citrulline malate, or about 3 to 4.5 grams of pure L-citrulline, taken before exercise.
- Evidence is moderate for reduced muscle soreness and small improvements in training volume.
- It appears to raise arginine levels more effectively than taking arginine itself.
How it works
Once absorbed, L-citrulline is converted in the kidneys into arginine, the amino acid your body uses to make nitric oxide. Nitric oxide helps blood vessels relax and widen, which can support blood flow to working muscles.
Interestingly, supplementing citrulline tends to raise blood arginine levels more reliably than supplementing arginine directly, because a large share of oral arginine is broken down before it reaches circulation.
What the evidence supports
The most consistent findings are modest. Several studies report reduced muscle soreness in the days after training and small increases in the number of reps performed before fatigue. Effects on strength and power are less consistent.
Think of citrulline as a supporting ingredient that may help you train slightly harder or recover a little more comfortably, not as a dramatic performance booster.
How to dose it
Research generally uses about 6 to 8 grams of citrulline malate taken roughly 30 to 60 minutes before exercise. If you are using pure L-citrulline rather than the malate form, an equivalent is around 3 to 4.5 grams.
Citrulline is water soluble and is usually well tolerated, with stomach upset being the main complaint at higher doses.
- Citrulline malate: 6 to 8 grams pre workout
- Pure L-citrulline: 3 to 4.5 grams pre workout
- Take about 30 to 60 minutes before training
Citrulline vs arginine
If your goal is raising arginine and nitric oxide, citrulline is generally the better choice because it survives digestion better and produces a more reliable rise in blood arginine. That is a big reason modern pre workouts favor citrulline over arginine.
Frequently asked questions
Both work. Malate is the form used in most studies at 6 to 8 grams. Pure L-citrulline needs a smaller gram amount for a similar citrulline dose.
About 30 to 60 minutes before exercise, so blood levels rise around the time you train.
It is generally well tolerated. The main side effect is mild stomach discomfort at higher doses. Check with a clinician if you take blood pressure medication.
References and Further Reading
How we researched this: Our editorial team reviewed current clinical research and guidance from independent health authorities before writing and reviewing this article. You can verify the science yourself through the sources below.
