Vitamin E protects guinea pig liver from lipid peroxidation without depressing levels of antioxidants

• Published in: The international journal of biochemistry & cell biology 1995-11, Vol.27 (11), p.1175-1181
• Main Authors: Cadenas, S., Rojas, C., Pérez-Campo, R., López-Torres, M., Barja, G.
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants; Antioxidants - metabolism; Ascorbic Acid - analysis; Diet; Free radicals; Glutathione - analysis; Guinea Pigs; Lipid peroxidation; Lipid Peroxidation - drug effects; Liver - drug effects; Liver - metabolism; Male; Oxidative Stress - physiology; Uric Acid - analysis; Vitamin E; Vitamin E - analysis; Vitamin E - pharmacology
• ISSN: 1357-2725; 1878-5875
• DOI: 10.1016/1357-2725(95)00077-3

Oxidative stress is considered a pathogenic factor in many disorders. The capacity of dietary vitamin E to increase global antioxidant capacity and to decrease lipid peroxidation was studied in the guinea pig, an animal that cannot synthesize ascorbate. Male guinea pigs were subjected for 5 weeks to three diets differing in vitamin E content in the presence of optimum levels of vitamin C: group 15 (15 mg vitamin E/kg diet), group 150 (150 mg/kg), and group 1500 (1500 mg/kg). Hepatic vitamin E increased in the three groups in relation to the level of vitamin E in the diet. The increase in vitamin E between groups 15 and 150 was accompanied by a reduction in sensitivity to enzymatic lipid peroxidation. This did not occur between groups 150 and 1500. The different liver vitamin E concentrations did not affect the antioxidant enzymes superoxide dismutase, catalase, GSH-peroxidase and GSH-reductase, nor the non-enzymatic antioxidants vitamin C, GSH and ascorbate. It is concluded that dietary supplementation with vitamin E, at a level 6 times higher than the minimum daily requirement for guinea pigs, increases protection against hepatic lipid peroxidation without depressing endogenous antioxidant defences. Further increases in vitamin E to megadose levels did not provide additional protection from oxidative stress. The results also suggest that optimum levels of both vitamin C and vitamin E, simultaneously needed for protection against oxidative stress, are much higher than the minimum daily requirements.