Long-term effects of vitamin E, vitamin C, and combined supplementation onurinary 7-hydro-8-oxo-2 '-deoxyguanosine, serum cholesterol oxidation products, and oxidation resistance of lipids in nondepleted men

We studied the long-term effects of vitamins E and C and their combination on lipid peroxidation in vivo and in vitro. The Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) trial is a double-masked placebo-cont rolled randomized clinical trial to study the effects of vitamin C (500 mg of slow release ascorbate per day), vitamin E (182 mg of RRR-alpha-tocopher ol acetate per day), and the combination of both antioxidants. Lipid peroxi dation measurements were carried out for 48 male participants at entry and at 12 and 36 months. Compared with placebo, vitamin E:and the vitamin combi nation increased plasma lipid-standardized alpha-tocopherol during the firs t 12 months by 68.2% and 65.2% (P<0.001 for both), respectively, and reduce d serum 7 beta-hydroxycholesterol by 50.4% (P= 0.013) and 44.0% (P=0.041), respectively. The net change of lipid standardized alpha-tocopherol was 63. 8% after 36 months of vitamin E supplementation and 43.3% for the combinati on. Vitamin C supplementation elevated plasma rotal ascorbate level by 30.1 % (P=0.043) in 12 months and by 91.1% (P=0.001) in 36 months. Neither vitam in E, vitamin C, nor the combination influenced the urinary excretion rate of 7-hydro-8-oxo-2'-deoxyguanosine or the antioxidative capacity of plasma. Vitamin E and the combination of vitamins E and C enhanced the oxidation r esistance of isolated lipoproteins and total serum lipids. Our data indicat e that long-term supplementation of nondepleted men with a reasonable dose of vitamin E alone or in combination with slow release vitamin C reduces li pid peroxidation in vitro and in vivo, whereas a relatively high dose of vi tamin C alone does not.