Bolus ingestion of white and green tea increases the concentration of several flavan-3-ols in plasma, but does not affect markers of oxidative stress in healthy non-smokers.

White tea (WT) is rich in flavan-3-ols as green tea (GT) and might provide health protective effects due to the strong antioxidant properties of flavan-3-ols. Since intervention studies with WT are lacking, we evaluated the effects of WT consumption on antioxidant status, antioxidant capacity and biomarkers of oxidative stress compared to water and GT. After an overnight fast, 70 healthy non-smokers were randomized to consume 600 mL of WT, GT or water (control). Plasma (epi-)catechin and epi(gallo)catechingallate, antioxidant capacity (Folin assay, trolox equivalent antioxidant capacity test), 8-iso-prostaglandin F(2α), ascorbic acid and uric acid were determined before and several times within 8 h after consumption. DNA strand breaks were measured in vivo and ex vivo (H(2)O(2) stimulation) in leukocytes. Plasma flavan-3-ols significantly increased after WT and GT ingestion. Trolox equivalent antioxidant capacity was lower after 5 h in controls versus WT (p = 0.031) and GT (p = 0.005). Folin-Ciocalteu reducing capacity, ascorbic and uric acid as well as markers of oxidative stress (8-iso-prostaglandin-F(2α), DNA strand breaks) were not affected by the beverages. A short-term increase of catechins does not change plasma antioxidant capacity in healthy subjects. Conclusions with respect to health protective effects of WT and GT on the basis of these biomarkers can, thus, not be drawn.

RCT Entities:   Population Interventions Outcomes