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L-Citrulline

What does the research say about L-Citrulline?

4 health outcomes synthesised

Research on L-Citrulline has investigated its effects on four health outcomes related to cardiovascular function. The strongest evidence—from 5 studies—supports a moderate improvement in flow-mediated dilation, a measure of endothelial function, with doses typically ranging from 6 to 10 g per day in adults with hypertension, diabetes, or heart failure. Additional research suggests possible benefits for blood pressure reduction, though these findings are more preliminary.

Strongest evidence: The most robust research on L-Citrulline is for Improved Flow-Mediated Dilation, where 5 out of 5 studies reported beneficial effects with moderate effect sizes. This evidence is rated as moderate in strength, with doses of 6–10 g/day over a median of 28 days showing consistent benefits in hypertensive adults, type 2 diabetes patients, and those with heart failure. Similarly, Reduced Aortic Systolic Blood Pressure also has moderate evidence, with all 4 studies showing benefit (moderate to large effects) at 6–10 g/day in comparable populations.

Mixed or weaker evidence: For Reduced Diastolic Blood Pressure, the evidence is low: only 2 of 4 studies found a benefit (small to moderate effects), while 2 found neutral results. The weakest evidence is for general Reduced Blood Pressure (3 studies, 1 beneficial, 2 neutral), where effects were small or absent and no consistent dose was identified.

Effective dose patterns: Across outcomes with moderate evidence, the most common effective dose range converges at 6–10 g/day, typically taken for 4 weeks (28 days). Lower doses (e.g., 3 g/day) appear less consistently effective.

Population insights: Research primarily targets clinical populations—hypertensive adults (including postmenopausal women), older adults, type 2 diabetes patients, and those with heart failure. Effects in younger, healthier adults are not well studied.

Notable caveats: The evidence base is small across all outcomes (3–5 studies each). Publication bias is a concern, as null results may be underreported. Most studies are short-term (≤12 weeks), and long-term efficacy and safety remain unclear. Many weaker outcomes failed to reach statistical significance, suggesting effects may be small or absent in some populations.

Frequently asked

  • What is L-Citrulline good for according to research?
    Research shows L-Citrulline may improve flow-mediated dilation, a measure of endothelial function, based on 5 studies with moderate evidence. It also shows potential for reducing aortic systolic blood pressure (4 studies, moderate evidence). Effects on diastolic blood pressure and general blood pressure are weaker and less consistent.
  • What dose of L-Citrulline is typically used in studies?
    The most common effective dose range across studies is 6–10 g per day. This range was consistently associated with benefits for flow-mediated dilation and aortic systolic blood pressure over a median study duration of 28 days. Optimal dosing is not yet established.
  • Who benefits most from L-Citrulline?
    Beneficial effects have been observed primarily in clinical populations: adults with hypertension (including prehypertensive and postmenopausal women), patients with type 2 diabetes, and those with heart failure with preserved ejection fraction. Effects in younger or healthier adults are not well studied.
  • Does L-Citrulline help with blood pressure?
    Evidence is mixed. For aortic systolic blood pressure, all 4 studies found a benefit (moderate evidence). For diastolic blood pressure, only 2 of 4 studies found an effect (low evidence), and for general blood pressure, only 1 of 3 studies found a small effect (low evidence). Results vary by population and measure.
  • Are there caveats or limitations in the research on L-Citrulline?
    Yes. The evidence base is small (3–5 studies per outcome), and most studies are short-term (≤12 weeks), leaving long-term efficacy unknown. Publication bias is possible, meaning null results may be underrepresented. Many findings, especially for blood pressure, did not reach statistical significance.
  • What is the strongest research finding for L-Citrulline?
    The strongest finding is for improved flow-mediated dilation, where all 5 studies reported beneficial effects with moderate evidence strength. This suggests L-Citrulline may support endothelial function in people with hypertension, diabetes, or heart failure at doses of 6–10 g/day.

Most-studied combinations with L-Citrulline

most supplement research is combination research
Also studied with:L-Arginine (5), watermelon (2)

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