Supplement Label Index

L-Arginine Hydrochloride vs. Arginine Nitrate

Among 1,304 on-market l-arginine products with an identifiable primary form, 43.2% use L-Arginine Hydrochloride (563 products) and 4.8% use Arginine Nitrate (62).

L-Arginine HydrochlorideArginine Nitrate
Quality tierUnratedUnrated
L-Arginine by weight82.7%73.4%
Share of market43.2%4.8%
On-market products56362
Median declared dose413.5 mg
middle half: 84.35–827
1,101 mg
middle half: 734–1,101
Most common brandsSource Naturals, Vitamin World, Best NaturalsCellucor, MusclePharm, Vital Performance

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 Nitrate is unrated

No head-to-head human bioavailability or efficacy comparison of this form was located in PubMed searches.

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