Antioxidative effect of dietary coenzyme Q10 in human blood plasma.

The effect of an oral dose of 90 mg/day coenzyme Q10 on the antioxidative status in 22 healthy young subjects (9 men and 13 women) was investigated before and after induction of an oxidative stress by fish oil supplementation. The levels of oxidised and reduced coenzyme Q10, alpha-tocopherol, ascorbate, TBARS and the fatty acid composition of phospholipids were determined in plasma. The total amount of plasma coenzyme Q10 increased significantly from 0.7 +/- 0.1 mumol/l before supplementation to 1.7 +/- 0.3 mumol/l after one week of supplementation while the redox status (reduced CoQ10/total CoQ10) remained constant, even during a following fish oil supplementation. The level of TBARS decreased during the first 2 weeks of CoQ10 ingestion while the content of alpha-tocopherol increased in the second week and ascorbate did not change. The decrease of TBARS and the presence of the majority of the orally supplemented CoQ10 in the reduced form in plasma seem to indicate an antioxidative role of CoQ10 in blood plasma.