L-Citrulline

瓜氨酸 Citrulline

Place · Level 3 · Supplement

西瓜里的非蛋白氨基酸 · NO 通路前体 · 比直接吃精氨酸更能升 Arg的反直觉

Connected to · 2

synergy · 1

Beta-Alanine
Pre-workout pair: citrulline → NO → blood flow ↑; beta-alanine → carnosine → H+ buffering. Different mechanisms, same window — combined effect strongest in multi-joint high-rep resistance.

cofactor · 1

Hypertension
Whether a vessel can relax comes down to endothelial nitric oxide. Dietary nitrate from leafy greens and beetroot is reduced by oral bacteria to nitrite and feeds the systemic NO pool — the mechanism under both DASH and the beetroot blood-pressure effect.

Identity

Stop 1/5

身份 · 反直觉的前体

L-citrulline is a non-protein amino acid: it doesn't enter the protein backbone, and doesn't directly trigger muscle synthesis the way leucine does.

The name comes from Latin *citrullus* (watermelon) — it was first isolated from watermelon in the 1930s; even today watermelon (especially the white rind near the skin) remains its best-known dietary source.

Its real role is as a precursor in the nitric oxide: A small signal molecule from the vessel lining that relaxes the vessel-wall muscle so the vessel widens. (nitric oxide) pathway:

Citrulline → arginine → NO

Here's a counter-intuitive fact: taking arginine (Arg) directly is less effective than taking citrulline. Oral Arg is mostly dismantled by hepatic arginase in first pass, so little reaches systemic circulation; citrulline bypasses hepatic metabolism, going straight to renal ASS/ASL, which converts it to Arg entering circulation.

Schwedhelm 2008 *BJCP* measured: at equal doses, oral citrulline raises plasma arginine AUC by +227%, far exceeding oral arginine itself.

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Educational content, not medical advice — consult a clinician.

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