The effect of vitamin E and vitamin C supplementation on LDL oxidizabilityand neutrophil respiratory burst in young smokers

Objective: The purpose of this study was to determine the effect of vitamin E and/or vitamin C supplementation on low-density lipoprotein (LDL) oxidiz ability and neutrophil (PMN) superoxide anion production in young smokers. Methods: Thirty smokers with a <5 pack-year history were randomly assigned to take placebo; Vitamin C (1 g/day); vitamin E (400 IU/day); or both vitam ins in a double-blind fashion. Subjects took the supplements for 8 weeks. A t weeks 0 and 8, blood was collected for isolation of LDL and PMN, and for antioxidant vitamin analysis. LDL was oxidized with a copper (Cu) catalyst, and oxidation was measured by formation of conjugated dienes over a 5-hour time course. Lag times and maximum oxidation rates were calculated from th e time course data. PMN superoxide anion release was assessed by respirator y burst after stimulation with phorbol ester and opsonized zymosan, and the ir ability to oxidize autologous LDL following treatment with the above sti muli was measured with the conjugated diene assay. Results: Subjects who received vitamin E alone had a significant increase i n the lag phase of Cu-catalyzed LDL oxidation (week 0, 118 +/- 31 min vs. w eek 8, 193 +/- 80 min, mean +/- SD, p < 0.05), whereas the vitamin C and pl acebo groups had no changes in LDL oxidation kinetics. The group receiving both vitamins E and C had a significant reduction in oxidation rate (week 0 , 7.4 +/- 2.3 vs, week 8, 5.1 +/- 2.1, p < 0.05). There were no significant changes for any group in PMN superoxide anion production or PMN LDL oxidat ion after stimulation with either phorbol ester or opsonized zymosan. Plasm a and LDL vitamin E concentrations were significantly increased in both gro ups that received vitamin E. The subjects who received vitamin C alone had no significant change in plasma vitamin C concentrations; however, when dat a were pooled from both groups who received vitamin C, the increases were s ignificant. Conclusion: Vitamin E supplementation of young smokers was effective in red ucing Cu-catalyzed LDL oxidizability; however, vitamin E and/or C supplemen tation showed few significant effects on the more physiologically relevant PMN function. This casts doubt on the ability of antioxidant supplementatio n to reduce oxidative stress in smokers in vivo. Therefore, smoking cessati on remains the only means by which young smokers can prevent premature coro nary heart disease.