L-Citrulline Supplement Benefits: What the Research Actually Shows
What citrulline is
Citrulline gets its name from watermelon, where it was first isolated. Your kidneys convert it into arginine, so it acts as a slower route to the same nitric-oxide pathway. In supplements it comes as L-citrulline (often as HCl) or citrulline malate, a pairing with malic acid.
Why it is popular
Because the gut breaks down much oral arginine, citrulline is often proposed as a more efficient way to raise arginine in the blood. That is the logic behind including both in formulas like HoneyPezil.
What studies examine
- Blood pressure: a review of oral L-arginine and L-citrulline and blood pressure found changes that depend on the population and dose.
- Exercise: a meta-analysis of citrulline and exercise performance reported mixed, generally small effects.
- Fatigue: one trial looked at citrulline malate and muscle fatigue.
- ne of these is a memory trial.
Safety and tolerance
A trial on graded oral citrulline in healthy adults found it was well tolerated at the tested doses over the study period. As with any supplement, tolerance in a study does not guarantee your response, and medicines that lower blood pressure can add to the effect. See what to ask your pharmacist.
Bottom line for readers
Citrulline is a legitimate, widely studied nutrient with a clear physiological role. The leap to memory is a hypothesis. If you try it in a product, track how you feel and keep your clinician informed.
Food sources
Watermelon is the best-known source, especially the rind and flesh near it, and other melons and cucumbers contain smaller amounts. Typical servings of food provide far less than capsule doses, so food is a gentle contributor, not a match for supplement amounts.
Who should be cautious
People on blood-pressure or nitrate medicines, and anyone with kidney or liver disease, should check with a clinician before using citrulline products.
Frequently asked questions
Sources
- PubMed: The effects of oral L-arginine and L-citrulline supplementation on blood pressure (2019)
- PubMed: Effects of citrulline supplementation on exercise performance in humans (2020)
- PubMed: The effect of citrulline malate supplementation on muscle fatigue among healthy participants (2019)
- PubMed: Subchronic tolerance trials of graded oral supplementation with ornithine hydrochloride or citrulline in healthy adults (2023)
General information, not medical advice. Offer details were checked on November 11, 2026; confirm on the order page and read the label on your bottle. See our disclaimer and how we research.