Flavonoids protect against oxidative damage to LDL in vitro: Use in selection of a flavonoid rich diet and relevance to LDL oxidation resistance ex vivo?

The ability of a range of dietary flavonoids to inhibit low-density lipopro tein (LDL) oxidation in vitro was tested using a number of different method s to assess oxidative damage to LDL. Overall quercetin was the most effecti ve inhibitor of oxidative damage to LDL in vitro. On this basis, a diet enr iched with onions and black tea was selected for a dietary intervention stu dy that compared the effect on the Cu2+ ion-stimulated lag-time of LDL oxid ation ex vivo in healthy human subjects of a high flavonoid diet compared w ith a low flavonoid diet. No significant difference was found in the Cu2+ i on-stimulated lag-time of LDL oxidation Ex vivo between the high flavonoid and low flavonoid dietary treatments (48 +/- 1.6 min compared to 49 +/- 2.1 min).