Effect of dietary vitamin C and catalase inhibition of antioxidants and molecular markers of oxidative damage in guinea pigs.

Guinea pigs were fed for five weeks with two diets with different levels of vitamin C, low (33 mg of Vit C/Kg diet) and high (13,200 mg of Vit C/Kg of diet). Catalase was inhibited with 3-amino-1,2,4-triazole (AT) in half of the animals from each dietary group. AT caused an almost complete depletion of liver catalase activity (90%) in both dietary groups. Vitamin C supplementation increased total glutathione peroxidase activity and tissue vitamin C level and decreased levels of protein carbonyls and malondialdehyde (MDA) in both treated and non-treated animals. This vitamin C supplementation did not change any of the other antioxidant defences studied. Our results show that dietary vitamin C supplementation increases global antioxidant capacity and decreases endogenous oxidative damage in the guinea pig liver under normal non-stressful conditions. This supports the protective value of dietary antioxidant supplementation.