Comparison

Quercetin 500 and Quercetin 1000 mg

Quercetin 500 (GNC) lists 2 distinct ingredients and Quercetin 1000 mg (GNC Preventive Nutrition) 1 (rows of one ingredient counted once); 1 are on both labels. On the site's similarity measure, which compares ingredient lists (1 for the same list, rarer ingredients counting for more; amounts are not part of it), the two formulas score 0.69.

Amount per serving (and % of the Daily Value)
Ingredient	Quercetin 500	Quercetin 1000 mg
Quercetin	500 mg	1,000 mg
Calcium	146 mg (11%)

Amounts are per serving as DSLD gives them: Quercetin 500, 1 tablet; Quercetin 1000 mg, 1 caplet. Current labels entered October 2011 and November 2011. Percentages of the Daily Value from 21 CFR 101.9. Source: NIH ODS Dietary Supplement Label Database.

Each product on its own

Quercetin 500GNC: every row against all products listing it
Quercetin 1000 mgGNC Preventive Nutrition: every row against all products listing it