How Products were Selected:
Products tested 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 direct sales. Products were not accepted directly from manufacturers.Testing Methods:
Products containing quercetin were tested in one or more independent laboratories for the following:- Quercetin and rutin by High Performance Liquid Chromatography (HPLC) methodology (USP/DSC 2022) or other appropriate methods determined by CL.
- Lead, cadmium, arsenic and mercury for all rutin products and any quercetin products claiming to contain whole herbs and/or 250 mg or more of minerals per daily serving by inductively Coupled Plasma/Mass Spectroscopy (ICP/MS).
- Disintegration of tablets (excluding chewable, sublingual and time release formulations) using United States Pharmacopeia (USP) <2040> methodology for disintegration of dietary supplements.
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 must meet the following requirements:- Quercetin: 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.
- Rutin: Products containing rutin must contain 100% and not more than 130% of the claimed amount of rutin in its claimed form (anhydrous or trihydrate). If the form is not claimed rutin will be reported on an anhydrous basis.
- Heavy metals: Rutin products and any quercetin product claiming to contain whole herbs and/or 250 mg or more of minerals per daily serving 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 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.
- 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).
- Contain less than 10 micrograms of total arsenic per daily serving (EPA limit and state of New Jersey limits — based on 1 liter of water). Products found to exceed this amount are tested for inorganic arsenic and must contain no more than 2.1 micrograms of inorganic arsenic per daily serving (Canada's limit in natural health products).
- May not exceed 2 micrograms of mercury per daily serving (based on EPA limit for mercury in 1 liter of water).
- Meet recommended USP <2040> parameters for disintegration of dietary supplements (excluding capsule, chewable, sublingual and time-release products).
- Be in compliance with FDA labeling requirements.
*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.
