Product Reviews
Quercetin Supplements Review
 


HOW PRODUCTS WERE EVALUATED:
How Products were Selected:

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

Testing Methods:
Products containing quercetin were tested in one or more independent laboratories for the following:
  1. Quercetin by High Performance Liquid Chromatography (HPLC) methodology or other appropriate methods determined by CL.
  2. Lead, cadmium, arsenic and mercury for all products by inductively Coupled Plasma/Mass Spectroscopy (ICP/MS).
  3. Disintegration time of Non-chewable, non-capsule, non-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.

ConsumerLab.com may modify or use other appropriate test methods if necessary to test special product formulations.

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

Passing Score:*
To be "Approved" by ConsumerLab.com, a product had to meet the following requirements:
  1. Products must contain a minimum of 100% and no more than 130% of the claimed amount of quercetin in its claimed form (anhydrous or dihydrate). If the form is not claimed quercetin will be reported on an anhydrous basis.
  2. Heavy metals: Products 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 single serving weights of less than 5 grams that 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 - 999 mg/day of any combination of elemental calcium, magnesium and potassium or 0.8 mcg if containing more than 1,000 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) or 1.0 mcg if containing 1000 mg/day or more whole herb (not extract). However, total lead allowance will not exceed 2 mcg.
    • 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 limit and state of New Jersey limits - based on 1 liter of water).
    Mercury:
    • Contain less than 2 micrograms of mercury per daily serving (based on EPA limit for mercury in 1 liter of water).
  3. Meet recommended USP <2040> parameters for disintegration of dietary supplements (excluding capsule, chewable, sublingual 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. ConsumerLab.com reserves the right to disqualify a product at any time from passing 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.

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





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