Modulation of aflatoxin biomarkers in human blood and urine by green tea polyphenols intervention

To evaluate the efficacy of green tea polyphenols (GTPs) in modulating aflatoxin B1 (AFB1) biomarkers, a total of 352 serum samples and 352 urine samples collected from a 3 month chemoprevention trial with 500 mg GTPs, 1000 mg GTPs and a placebo were measured for AFB1–albumin adducts (AFB–AA), aflatoxin M1 (AFM1) and aflatoxin B1–mercapturic acid (AFB–NAC). Levels of AFB–AA at baseline were comparable for all three dose groups (P = 0.506). No significant differences were observed in AFB–AA levels in the placebo group over the 3 month period (P = 0.252). However, a significant reduction in AFB–AA levels was observed in the 500 mg group (P = 0.002). A marginally significant reduction in AFB–AA levels was also found in the 1000 mg group over the 3 month intervention period (P = 0.051). An analysis using a mixed-effects model indicated that the reduction in AFB–AA levels over time was dose and time dependent (dose–time interaction P = 0.049). There were no significant differences in median AFM1 levels among the three study groups at the baseline (P = 0.832), 1 month (P = 0.188) and 3 months (P = 0.132) of the GTP intervention; however, reduction of 42 and 43% in median AFM1 levels, as compared with the placebo, were found in 500 mg (P = 0.096) and 1000 mg (P = 0.072) groups at 3 months of the intervention. Significant elevations in median AFB–NAC levels and the ratio of AFB–NAC:AFM1 were found in both 500 and 1000 mg groups compared with the placebo group at both 1 month (P