Effects of moderate dose (400 IU/day) oral vitamin E supplemention on plasma lipoproteins and lipid peroxidation in IDDM

Abstract

Many patients with diabetes self-medicate with moderate doses of vitamin E, believing this will improve their health. We therefore examined the effects of oral supplementation with 400 IU/day of vitamin E (d-alphatocopherol), on plasma lipoproteins and lipid peroxidation in 12 patients with insulin-dependent diabetes mellitus, in a randomised, crossover study. There were no differences in any outcome measures between active treatment and placebo and so this study did not demonstrate any effect of moderate dose vitamin E on plasma lipoprotein levels or peroxidation. However, subgroup analysis showed that whilst in five subjects there was only minor vitamin E enrichment of plasma lipoproteins on active treatment despite good compliance, in seven subjects there was significant enrichment. In the latter, several measures of lipid peroxidation were lower on active treatment [placebo vs active treatment, median (interquartile range), Wilcoxon's signed rank test]: conjugated dienes 19.2 (15.3-26.4) vs 13.1 (7.49-14.3) μmol/l, p < 0.05; diene conjugation index 0.83 (0.67-0.96) vs 0.53 (0.38-0.6) x 10-2, p < 0.05). Thus the effects of moderate dose vitamin E supplements merit further study, particularly as, in large epidemiological studies, their use is associated with a reduced risk of ischaemic heart disease.