Antioxidants and cardiovascular disease

Abstract

Oxidauve modification of LDL-cholesterol is thought to be an important process in the early development of atherosclerosis. The evidence for a beneficial effect of antioxidant vitamins cardiovascular disease stems largely from biochemical investigations, experimental animal studies as well as observational epidemiological trials. Large-scale prospective intervention trials to test natural antioxidants in atherosclerosis, however, are awaiting completion. We determined if the dietary intake or plasma levels of anu'-oxidant vitamins was associated with the extent of atherosclerosis as assessed by carotid intima-media wall thickness (IMT) in a randomly selected adult population. We studied 1,100 subjects (548 males, 552 females) aged 52 ± 13 (mean ±SD; range 26 - 76) years recruited from a random electoral roll survey. Dietary and supplemental vitamin intake of carotenoids, vitamin (vit) E and vit C were assessed by a validated semi-quantitative food-frequency questionnaire. Conventional vascular risk factors were also assessed. Fasting plasma levels of vit E, vit C, lycopene, a and B carotene were measured by HPLC. Bilateral carotid B-mode ultrasound was performed according to a standardized protocol. Vitamin supplement intake was more prevalent among females (29% versus 8% of males, p <0.01 for difference). Dietary vitamin intake was correlated with the respective plasma levels (r =0.32 0.34, all p <0.01). Carotid IMT was negatively correlated with dietary vit E (r = -0.15, p <0.01), plasma lycopene (r = -0.21, p <0.01). On multivariate analysis age, systolic BP, smoking, HDL-cholesterol and dietary vit E, but not supplement use or plasma vitamin levels, were found to be independent predictors of carotid IMT (R2 for model =0.51, p <0.001). In a random adult population dietary intake of vitamin E, but not other anti-oxidant vitamins or their plasma levels, was associated with the extent of carotid atherosclerosis after adjustment for standard risk factors.