Product Reviews
L-Arginine Supplements Review
Reviewed and edited by Tod Cooperman, M.D. Tod Cooperman, M.D.

How Products were Selected:

Products selected represent those commonly sold and/or available nationally in the U.S. purchased products on the open market through retail stores, on-line retailers, catalogues, or multi-level marketing companies. Products were not accepted directly from manufacturers.

Testing Methods:
  1. Analyses for L-arginine using High Performance Liquid Chromatography (HPLC) methodology.
  2. Quantitative analyses for lead, cadmium and arsenic by ICP/MS (Inductively Coupled Plasma-Mass Spectroscopy) for products containing whole herbs and/or more than 250 mg of minerals per daily dose.
  3. Disintegration of non-chewable, non-capsule, sublingual and non-time-release formulations using United States Pharmacopeia (USP) <2040> recommendations entitled "Disintegration and Dissolution of Nutritional Supplements."

Any product not passing testing was sent to another independent laboratory to repeat testing for the criterion on which it did not pass. may modify or use other appropriate test methods if necessary to test special product formulations.

Identities of products were not disclosed to laboratories performing the testing.

Passing Score:*
To be "Approved" by, a product must meet the following requirements:
  1. 1. Must meet 100% of label claim for L-arginine (free base) or L-arginine complexes (e.g. arginine hydrochloride).
  2. Heavy Metals: Products containing whole herbs and/or 250 mg of minerals per daily dose must not exceed the following limits:
    • Products marketed for use by children may not exceed the State of California's Prop 65 limits for lead in dietary supplements of 0.5 mcg per recommended daily serving with an additional allowance of 0.8 mcg if the product contains more than 1,000 mg/day of calcium.
    • Products with a single serving weights of less than 5 grams which are not marketed for use by children, may not exceed the State of California's Prop 65 limits for lead in dietary supplements of 0.5 mcg per recommended daily serving with an additional allowance of 0.4 mcg if containing 250 to 999 mg/day of elemental calcium, potassium and magnesium, 0.8 mcg if containing1000 mg/day of any combination of these minerals. An additional 0.5 mcg is provided if containing 250-999 mg/day of whole herb (not extract) ingredient or 1.0 mcg for products containing1000 mg/day or more of whole herb (not extract)). However, total lead allowance will not exceed 2 mcg per daily serving.
    • Products with single serving weights of 5 grams or more which are not marketed for children may not exceed 2.5 mcg per serving nor 4.0 mcg per daily serving.
    Cadmium**: If marketed for use by children, may not exceed 3.0 micrograms of cadmium per recommended daily serving (based on Canada's limit for a child weighing 75 lbs.). If not marketed for use by children, may not exceed 4.1 micrograms of cadmium per recommended daily serving (based on the State of California's Prop 65 limit).
    Arsenic: Contain less than 10 micrograms of total arsenic and no more than 5 micrograms of inorganic arsenic per daily serving (EPA and state of New Jersey limits - based on 1 liter of water.
  3. If applicable to the product, it must meet recommended USP <2040> parameters of disintegration for dietary supplements (excluding capsule, chewable and time-release products).
  4. Be in compliance with FDA labeling requirements.
A "Pass" was based on meeting the above criteria in either the first or second rounds of testing.

* Passing scores allow for specific margins of technical error associated with each analysis. reserves the right to disqualify a product at any time from passing its testing if it considers such product to present a safety risk or to provide misleading or inaccurate information in its labeling.

** Based on State of California's Prop 65 lead limit. California requires supplements exceeding this limit to bear a warning label regarding lead.

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