Lipoprotein oxidation profile in end stage renal disease patients. Role of vitamin C supplementation

BACKGROUND: The aim of the study was to analyze the lipid and lipoprotein oxidation profile in patients with end stage renal disease who started haemodialysis and also to evaluate the possible effect of haemodialysis and vitamin C supplementation on lipoprotein oxidation one year after the initiation of the therapy. METHODS: Forty-one end stage renal disease patients who started haemodialysis between January 1999 and January 2000 were enrolled in the study. The patients were randomised to receive 1,000 mg/day of vitamin C or placebo and then hemodialysis was initiated. We measured the lipid profile and the susceptibility of LDL and HDL to oxidation using cooper ions, at the moment of inclusion and one-year after the treatment. RESULTS: No significant differences were observed among the vitamin-C treated patients and those who received placebo. Our results show that haemodialysis by itself did not induce deletereous effects on the lipid profile, which was slightly improved. A small decrease in total cholesterol--183 to 164 mg/dl (group A), 170 to 144 mg/dl (group B); in LDL cholesterol (100 mg/dl to 79 mg/dl (group A), 88 mg/dl to 73 mg/dl (Group B); and in phospholipids [198 to 188 mg/dl, group A (Group A), 195 mg/dl to 178 mg/dl (Group B)], was observed in all the patients one year after starting haemodialysis. When considering oxidation-derivative products, the lag phase of LDL-cholesterol and HDL-cholesterol was enlarged but without statistical significance. A tendency to increase the vitamin E generation in HDL and LDL lipoproteins was observed in vitamin-C treated patients, but the difference still remained not significant. CONCLUSIONS: Haemodialysis by itself could improve lipid profile in patients with a previous pro-oxidative state such as uraemia. Although our results have failed to demonstrate significant differences between vitamin C-treated and not treated patients, the tendency to decrease oxidation products by supplementation of vitamin C could mean a beneficial effect on oxidation parameters. In order to improve oxidative stress, the use of lipophylic more than hydrophilic vitamins could be evaluated in randomized studies with a more important number of patients.