L-Arginine Hydrochloride

L-Arginine Hydrochloride is a unrated form of L-Arginine, used in 611 on-market products and providing 82.7% elemental l-arginine by weight.

Basis: C6H14N4O2 x HCl, 1:1 (arginine 174.20 / 210.66); some labels list the monohydrate

Why this tier: Largest disclosed salt form; no human head-to-head bioavailability study of arginine HCl vs free arginine or other salts was located. The best-supported finding on arginine delivery is that oral citrulline raises plasma arginine more effectively than oral arginine itself (a separate compound).

Source: Schwedhelm E et al. 2008, Br J Clin Pharmacol 65(1):51-9, PMID 17662090 (citrulline vs arginine, not salt forms)

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