Effect of increased fruit and vegetable intake on the susceptibility of lipoprotein to oxidation in smokers

Objective: To evaluate the effect of an increased dietary intake of fruit and vegetables on susceptibility of LDL to oxidation in smokers and nonsmokers. Design: A descriptive and prospective study. Setting: Joseph Fourier University, Grenoble. Subjects: Volunteers were age and sex matched in the smoking and nonsmoking groups and were recruited by announcement. Interventions: Increased intake of fruits and vegetables for two weeks providing 30 mg/day of carotenoids. Main outcome measures: Circulating levels of beta-carotene, lutein, lycopene, alpha-tocopherol; susceptibility of LDL to oxidation. Cu-Zn superoxide dismutase (Cu-Zn SOD), and Se glutathione peroxidase (Se-GSH-Px) activities and reduced (GSH) and oxidized (GSSG) glutathione. Results: At entry (week 0: WO) smokers exhibited a lower plasma carotene level but the plasma parameters of oxidative stress and LDL oxidizability were not different from nonsmokers. After two weeks of increased intake of fruits and vegetables the circulating levels of carotenoids increased in smokers 23% and 11% in nonsmokers. At the same time the resistance of LDL to oxidation increased by 14% in smokers (P less than or equal to 0.05) and by 28% in nonsmokers (P less than or equal to 0.025). The mean whole bloodGSH level was higher in smokers at entry but returned to a concentration similar to nonsmokers at the end of the study. Conclusion: This pilot study indicates that an increased, carotenoid rich food intake through its inhibitory effect on the susceptibility of LDL to oxidation may be an interesting approach to reduce the risk of atherosclerosis both in smokers and nonsmokers.