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About ConsumerLab.com


How Products Were Selected:

Products were selected to represent those popular among readers of Consumerlab.com and commonly available nationally in the U.S. and Canada. ConsumerLab.com purchased products on the open market through retail stores, on-line retailers, and direct sales companies. Products were not accepted directly from manufacturers..

Testing Methods:

Vitamin C products were tested in one or more independent laboratories for the following:
  1. Ascorbic acid by High Performance Liquid Chromatography (HPLC).
  2. Lead, cadmium, arsenic, and mercury content by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) for products containing whole herbs and/or more than 250 mg of minerals per daily dose.
  3. Disintegration of tablets (excluding chewable, sublingual and timed release formulations) was performed utilizing United States Pharmacopeia (USP) <2040> methodology for the disintegration of Dietary Supplements.
Testing was performed by one or more independent laboratories. Any product that did not initially pass testing (as defined below) was sent to another independent laboratory to repeat testing for the criteria on which it did not pass.

ConsumerLab.com 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 Consumerlab.com, a product must meet the following requirements:
  1. Contain a minimum of 100% and no more than 120% of its labeled amount of ascorbic acid.
  2. Heavy Metals: Products containing whole herbs and/or more than 250 mg of minerals per daily dose must not exceed the following limits:
    Lead:
    • 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 (above which a warning regarding reproductive harm, birth defects, or cancer risks is required in California) with an additional allowance of 0.4 mcg if containing 250-999 mg/day of any combination of elemental calcium, magnesium and potassium, 0.8 mcg if containing 1000 mg/day of any combination of these minerals. An additional allowance of 0.5 mcg is provided if containing 250-999 mg/day of whole herb (not extract) ingredient or 1.0 mcg for products containing 1000 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 (above which California's Prop 65 law requires a "reproductive harm" warning due to developmental toxicity and male reproductive harm).
    Arsenic:
    • Contain less than 10 micrograms of total arsenic per daily serving (based on Canada‚Äôs limit per daily serving of a natural health product, and U.S. EPA and state of New Jersey limit in 1 liter of water). Products found to exceed this amount were tested for inorganic arsenic and must not contain more than 2.1 micrograms of inorganic arsenic per daily serving (Canada's additional limit in natural health products).
    Mercury:
    • May not exceed 2 micrograms of inorganic mercury per daily serving (based on EPA limit for mercury in 1 liter of water).
  3. If applicable to the product, must meet recommended USP <2040> recommendations for disintegration of dietary supplements (excluding chewable, sublingual and timed-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. ConsumerLab.com reserves the right to disqualify a product at any time from passing its testing if it considers such product to display unacceptable variation in quality, present a safety risk or to provide misleading or inaccurate information in its labeling.

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