Influence of acute ingestion and regular intake of green tea catechins on resting oxidative stress biomarkers assays in a paralleled randomized controlled crossover supplementation study in healthy men

In this paralleled randomized controlled crossover study, we examined the hypothesis whether acute or regular green tea catechins (GTC) supplements have the potential to stimulate resting oxidative stress metabolites in healthy individuals. Sixteen subjects were randomly divided equally and assigned into regular intake (GTC-RI) or control group (GTC-CG) after the screening. GTC-RI group consumed 780 mg/day EGCG-enriched GTC (506 mg EGCG). While GTC-CG received water under the identical diet regime and lifestyle conditions. Then the GTC-CG crossed over to acute intake (GTC-AI) group and consumed a single dose of 780 mg ECGC-enriched GTC. Blood aliquots were collected at baseline and after GTC ingestion according to the prescribed study protocol. We measured oxidative stress blood biomarkers using the diacron reactive oxygen metabolite (d-ROMs) and biological antioxidant potential (BAP) tests. Urinary 8-hydroxydeoxyguanosine (8-OHdG) and 8-OHdG/creatinine were also analyzed. Analysis of variance (ANOVA) was used to determine statistical significance (P < 0.05) within the group as well as between and among the groups. The relative ratio of BAP and 8-OHdG concentrations to baseline showed statistical significance (P < 0.05) between the GTC-AI and GTC-RI groups and among all groups as determined by two-way repeated measures factorial ANOVA. The present results support the importance of appropriate GTC intake as antioxidant supplements for reducing oxidative stress that might lead to a sedentary behavior under resting conditions. Regular intake of GTC offers protection against oxidation-induced DNA damage in healthy humans and decreased oxidative stress. When GTC is taken in safe dosages under acceptable limits they reduce oxidative stress via associated and/or unassociated oxidant effect without any relevant pro-oxidant activity related to redox-sensitive adaptations.