Comparison

Flavonoids and Quercetin 250 mg

Flavonoids (Intensive Nutrition) lists 2 distinct ingredients and Quercetin 250 mg (BIOVEA) 3 (rows of one ingredient counted once); 2 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 0.81.

Amount per serving (and % of the Daily Value)
Ingredient	Flavonoids	Quercetin 250 mg
Flavonoid	39 mg	25 mg
Quercetin	95 mg	500 mg
Vitamin C		1,000 mg (1111%)

Amounts are per serving as DSLD gives them: Flavonoids, 1 capsule; Quercetin 250 mg, 2 vegetarian capsules. Current labels entered August 2013 and October 2019. Percentages of the Daily Value from 21 CFR 101.9. Source: NIH ODS Dietary Supplement Label Database.

Each product on its own

FlavonoidsIntensive Nutrition: every row against all products listing it
Quercetin 250 mgBIOVEA: every row against all products listing it