NO EFFECT OF SUPPLEMENTATION WITH VITAMIN-E, ASCORBIC-ACID, OR COENZYME-Q10 ON OXIDATIVE DNA-DAMAGE ESTIMATED BY 8-OXO-7,8-DIHYDRO-2'-DEOXYGUANOSINE EXCRETION IN SMOKERS

The protective effect of fruit and vegetables against cancer has been related to their high antioxidant content. However, results from inter vention trials have not been conclusive on the protective effect of an tioxidant supplementation. In a randomized placebo-controlled trial we investigated the effect of dietary supplementation with antioxidants on a biomarker of oxidative DNA damage with mechanistic relation to ca rcinogenesis. One hundred forty-two smoking men aged 35-65 y were rand omly assigned to one of the following seven treatments for 2 mo: 100 m g D-alpha-tocopheryl acetate plus 250 mg slow-release ascorbic acid tw ice a day (n = 20), 100 mg D-alpha-tocopheryl acetate twice a day (n = 20), 250 mg ascorbic acid twice a day (n = 21), 250 mg slow-release a scorbic acid twice a day (n = 21), 30 mg coenzyme Q10 in oil three tim es a day (n = 20), 30 mg coenzyme Q10 as granulate three rimes a day ( n = 20), or placebo twice a day (n = 20). The trial outcome was the ur inary excretion rate of 8-oxo-7,8 -dihydro-2'-deoxyguanosine (8-oxodG) -a repair product of oxidative DNA damage. Two months of supplementati on did not result in significant changes in the urinary excretion rate of 8-oxodG in any group. The lack of effect of antioxidant supplement ation on the excretion rate of 8-oxodG, despite substantial increases in plasma antioxidant concentrations, agrees with the results from rec ent large intervention studies with cancer as an endpoint. The cancer- protective effect of fruit and vegetables seems ro rely not on the eff ect of single antioxidants but rather on other anticarcinogenic compou nds or on a concerted action of several micronutrients present in thes e foods.