The increase in human plasma antioxidant capacity after acute coffee intake is not associated with endogenous non-enzymatic antioxidant components

This study evaluated the association between the main plasma endogenous non-enzymatic antioxidant components and the increase in human antioxidant capacity (AC) after acute coffee intake. Ten adults were tested before and 90 min after consumption of coffee or water, in a crossover design, with a 7-day interval between tests. AC (FRAP and TRAP), ascorbic acid, α-tocopherol and γ-tocopherol, albumin, bilirubin and uric acid were analyzed in plasma/serum. After coffee consumption FRAP and TRAP increased 2.6% and 7.6% (P<0.05), whereas after water consumption FRAP and TRAP decreased 2.5% and 1.0% (P <0.05), respectively. In general, AC assays correlated with uric acid and α-tocopherol (r >0.75; P <0.04), independently of treatment and time point. Changes in AC assays after coffee intake did not correlate with endogenous components, which remained unchanged. These results suggest that coffee components spare endogenous antioxidants or are themselves the main contributors to plasma AC increase after coffee intake.