THE EFFECT OF PHARMACOLOGICAL SUPPLEMENTATION WITH VITAMIN-C ON LOW-DENSITY-LIPOPROTEIN OXIDATION

Aims Vitamin C (ascorbic acid) is a powerful antioxidant bur. there is limited information on its ability to prevent LDL oxidation and its i nteraction with other natural antioxidants in vivo. We assessed the ef fect of 4 weeks pharmacological supplementation with vitamin C 1 g day (-1) on copper induced LDL oxidation and lipid peroxidation. Methods B lood samples were obtained at baseline and at the end of 4 weeks suppl ementation from 11 healthy non-smokers and also from nine control subj ects. Plasma lipid peroxides were measured as malondialdehyde (MDA) by h.p.l.c. The relationship between vitamin C and two other important a ntioxidants, vitamin E and glutathione, was also studied. Results Ther e was no difference in baseline values between the two groups and the oxidizability of LDL, assessed as the lag phase of conjugated dienes p roduction and the formation of thiobarbituric acid reactive substances (TBARS), remained unchanged after 4 weeks. In the vitamin C supplemen ted group only, there was a 2.2-fold increase in plasma ascorbic acid level and a 28% increase in red cell reduced glutathione (GSH) (P < 0. 001). Vitamin E, measured as alpha-tocopherol, in red cells increased significantly (P < 0.02) and plasma MDA was reduced (P < 0.01). Conclu sions Vitamin C did not alter LDL oxidation but it may have a protecti ve role against lipid peroxidation as shown by decreased plasma MDA le vels and enhanced vitamin E and GSH status.