Resveratrol Supplements Review (Grape, Red Wine, and Polygonum Sources)
HOW PRODUCTS WERE EVALUATED:
How Products were Selected:
Products tested represent those commonly sold and/or 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 or multi-level marketing companies. Products were not accepted directly from manufacturers.
Any product not passing testing was sent to another independent laboratory to repeat testing the criteria on which it did not pass.
- Quantification of total resveratrol content including trans/cis resveratrol and trans/cis polydatin and the dimethylated derivative pterostilbene by High Performance Liquid Chromatography (HPLC). Products not passing this initial assay were tested in a second independent laboratory utilizing a similar HPLC assay.
- Analyses for lead, arsenic and cadmium by inductively Coupled Plasma-Mass Spectroscopy (only for products containing whole herbs and/or more than 250 mg of minerals per daily dose).
- Disintegration of non-chewable, non-capsule, non-enteric coated and non-time-release formulations was analyzed utilizing USP (United States Pharmacopeia) <2040> recommendations entitled "Disintegration and Dissolution of Nutritional Supplements."
Identities of products were not disclosed to laboratories performing the testing.
ConsumerLab.com may modify or use other appropriate test methods if necessary to test special product formulations.
To achieve a "Pass" in the testing a product had to:
A "Pass" was based on meeting the above criteria in either the first or second rounds of testing.
- Contain 100%, and not more than 130%, of the claimed amount of resveratrol and specific resveratrol forms. Total resveratrol = sum of (total free trans/cis resveratrol) + (total trans/cis polydatin x 0.587) (note: polydatin glycoside is composed of 58.7% resveratrol).
- Contain 100% and not more than 130% of the claimed amount of pterostilbene.
- Heavy Metals: Products containing whole herbs and/or more than 250 mg of minerals per daily dose must not exceed the following limits:
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).If marketed for use by children, may not exceed 3.0 micrograms 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).
- 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 of lead per daily serving with an additional allowance of 0.8 mcg if the product contains 1,000 mg/day of elemental 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 any combination of elemental calcium, magnesium and potassium or 0.8 mcg if containing more than 1000mg/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). 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.
Arsenic: Contain less than 10 micrograms of total arsenic and no more than 5 micrograms of inorganic arsenic per daily serving (EPA limit - based on 1 liter of water).
- If applicable to the product, it must meet recommended USP <2040> parameters of disintegration for dietary supplements (excluding capsule, chewable 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 its testing if it considers such product to present a safety risk or to provide misleading or inaccurate information in its labeling.
** If available for sale in California, a product that exceeds the State of California's Prop 65 lead limit requires a warning label. However, with or without this warning label, a product cannot pass ConsumerLab.com testing if it exceeds the levels described this paragraph.
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