Reduced Coenzyme Q10 Decreases Urinary 8-Oxo-7,8-Dihydro-2'-Deoxyguanosine Concentrations in Healthy Young Female Subjects.

It remains unclear whether dietary supplementation with coenzyme Q10 (CoQ10) provides beneficial effects for healthy individuals, especially young subjects. This study investigated the effects of dietary supplementation with CoQ10 on oxidative stress in healthy young females. We performed a placebo-controlled trial using a crossover design (n=28) with 100 mg/day CoQ10 in reduced form or placebo, each lasting 2 weeks with a 2-week interval. The urinary levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a biomarker of oxidative DNA damage, were determined by high-performance liquid chromatography (HPLC) coupled to an electrochemical detector. Levels of malondialdehyde (MDA), a biomarker of lipid peroxidation, and antioxidant vitamin C in urine were also measured using a thiobarbituric acid-reactive substance method with a commercial kit and by the 2,4-dinitrophenylhydrazine method with HPLC, respectively. Urinary 8-oxodG levels during supplementation with reduced form of CoQ10 (median [first and third quartiles]: 1.76 [1.24-2.08] nmol/mmol creatinine) were significantly lower than those with placebo (2.00 [1.34-2.49] nmol/mmol creatinine, P=.031 by Student's paired t-test using the logarithmically transformed values). In contrast, the urinary levels of MDA and vitamin C were not significantly affected (P=.094 and P=.247 by Student's paired t-test, respectively). There was no evidence of any side effects. Supplementation with CoQ10 in the reduced form showed a slightly protective effect against oxidative DNA damage even in healthy young subjects.