Supplement Label Index

L-Arginine Hydrochloride vs. Arginine Silicate Inositol Complex (Nitrosigine-type)

Among 1,304 on-market l-arginine products with an identifiable primary form, 43.2% use L-Arginine Hydrochloride (563 products) and 7.2% use Arginine Silicate Inositol Complex (Nitrosigine-type) (94).

L-Arginine HydrochlorideArginine Silicate Inositol Complex (Nitrosigine-type)
Quality tierUnratedUnrated
L-Arginine by weight82.7%—
Share of market43.2%7.2%
On-market products56394
Median declared dose413.5 mg
middle half: 84.35–827
—
Most common brandsSource Naturals, Vitamin World, Best NaturalsPS ProSupps, MuscleTech Performance Series, Axe & Sledge Supplements

Doses are declared per serving in mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).

Why L-Arginine Hydrochloride is unrated

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)

Why Arginine Silicate Inositol Complex (Nitrosigine-type) is unrated

Branded complex with its own small trials (e.g. acute vasodilation and cognition studies); no comparison against other arginine forms was verified.

Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology). This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.

Other l-arginine comparisons