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L-Citrulline

An amino acid studied for blood flow and exercise performance.

Supplements

Fitness & muscle

Research records

Historical source snapshot. Not freshly verified, not a recommendation. Study findings, community accounts and app defaults are not interchangeable.

Publication suitability · 2026-10-15: Historical reference only; not a clinical verification. Clinical, regulatory, efficacy, safety and dose claims are not independently established by this review.

L-Citrulline

An amino acid studied for blood flow and exercise performance.

Evidence category: Systematic review. This describes the source category, not approval or certainty.

Regulatory statement in source: Not separately recorded; do not infer approval from the evidence category.

L-citrulline is a non-essential amino acid, naturally concentrated in watermelon, that the body converts to arginine and ultimately nitric oxide, a molecule involved in blood vessel dilation. It has been studied mainly as a pre-exercise ergogenic aid in athletes and recreationally active adults, with trials measuring aerobic performance, perceived exertion, and blood lactate. Findings across published trials remain inconsistent, with meta-analyses reporting no clear overall benefit for aerobic performance despite a possible trend favoring longer supplementation protocols.

Benefits reported in the imported source

  • May modestly support nitric-oxide-related blood flow in some individuals
  • Chronic-use protocols in trials showed a non-significant trend toward improved endurance performance

Risks and limits

  • Gastrointestinal discomfort has been reported in some trial participants
  • Evidence for a real performance benefit is inconsistent across independent meta-analyses

Source bottom line: Trial evidence on aerobic performance is mixed, and the largest pooled meta-analysis found no significant overall benefit, so citrulline's ergogenic effect remains unproven despite its popularity as a pre-workout ingredient.

Uncertainty: Reference information only. Not medical advice.

Study protocols — reports, not instructions

Ten randomized controlled trials in trained and recreationally active adults performing aerobic exercise tests

Reported regimen
Pooled meta-analysis of acute and chronic citrulline supplementation protocols, most using 3 to 6 g given 40 to 60 minutes before exercise, compared against placebo across the included trials
Duration
Acute and chronic protocols pooled across the ten trials
Reported outcome
No significant pooled effect on aerobic exercise performance, perceived exertion, oxygen-uptake kinetics, or blood lactate; a positive trend appeared only in chronic-use subgroups, and the authors called for further research
Source
Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis - PubMed
Claim provenance

evidence.json#/catalog:supplement:citrulline/protocols/0

Community and practice descriptions

Accounts of a practice are not evidence of safety or effectiveness. Words such as “standard”, “safe” or “recommended” describe the source account, not verified consensus or this wiki’s advice. Commercial and self-published citations are retained for traceability, not vendor endorsement or independent clinical corroboration.

Historical research outcome: no-verified-description · 2026-10-06

No suitable community description was independently verified in these checks. The entry remains empty; this does not establish that no practice exists elsewhere. The excerpt establishes an ingredient's presence in watermelon, not a community supplementation routine.

Pharmacokinetic context

Historical half-life estimate: 0.65–1.14 hours. Moinard et al. 2008, Br J Nutr, PMID 17953788 — dose-dependent (2-15 g oral); citrulline converts to arginine, but the authors could not compute a reliable arginine half-life from the resulting decay curves Population/route context and estimates may differ. This is not a schedule or a verified human dosing rule.

Source references

Snapshot provenance

Source ID: catalog:supplement:citrulline. Commit: adc7684614f9439b41d91a3312b62e7982c7e20e. Review state: historical-not-reverified. Authored links are retained separately from the canonical evidence links in the public data. App templates/defaults and rejected drafts are archived, not deployed.

Related entries and components

None listed.