L-Citrulline

Also known as: citrulline, L-citrulline, citrulline malate

Confidence

research strength

BBuilding confidence68117 studies referenced

Latest evidence update: 2026-06-11

Strongest in Replication (79). Held back by Recency (23).

Study quality (37%)

Study design (21%)

Risk of bias (16%)

Solid mix of RCTs with some methodological gaps.

Replication (26%)

Cross-study replication (21%)

Precision (5%)

Confirmed across many independent studies with significant findings.

Sample size (16%)

Thousands of participants across the literature.

Consistency (11%)

Mostly aligned, with some divergence.

Recency (10%)

Mostly pre-2020 research; updates may be needed.

Effect by outcome

how big the change is

Effect-size tagged on 342 of 400 claims for this supplement. Our research updates daily; remaining claims are pending re-processing.

Directional evidence

Areas where research points to a consistent direction of effect. The strength of evidence is graded; the size of the effect is not quantified.

Common dosage

3 to 6 g L-citrulline daily for vascular benefits (building over 1 to 2 weeks), or 8 g citrulline malate taken 60 minutes before exercise.

Description

L-Citrulline is a non-essential amino acid and nitric oxide precursor that raises plasma arginine more effectively than arginine itself. It is best evidenced for lowering blood pressure and improving endothelial and vascular function, and is also used before exercise for blood flow and performance. The malate salt, Citrulline Malate, is the common pre-workout form.

Safety & interactions

Generally well tolerated, with mild gastrointestinal discomfort possible at high doses. May add to the blood-pressure-lowering effect of nitrates and PDE5 inhibitors.

Check interactions with other supplements→

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Order L-Citrulline

Recommended: 3 to 6 g L-citrulline daily for vascular benefits (building over 1 to 2 weeks), or 8 g citrulline malate taken 60 minutes before exercise.

Forms of L-Citrulline

Specific salts and chemical forms studied in research. Bioavailability, dose, and clinical use case differ across forms. See each form's page for form-specific evidence.

Citrulline Malate

72 studies

BBuilding confidence

Questions about L-Citrulline

Who has been studied for L-Citrulline?

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Referenced studies (117)

ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.