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Antioxidant vitamins and low-density-lipoprotein oxidation
M Abbey1, P J Nestel, P A Baghurst
1CSIRO, Division of Human Nutrition, Adelaide, South Australia.
The American Journal of Clinical Nutrition
|October 1, 1993
Summary
Antioxidant supplements like beta-carotene, vitamin C, and alpha-tocopherol significantly increased the lag time before low-density-lipoprotein (LDL) oxidation. This suggests a protective effect against LDL oxidation, particularly linked to alpha-tocopherol levels.
Area of Science:
- Biochemistry
- Nutritional Science
- Cardiovascular Research
Background:
- Oxidation of low-density-lipoprotein (LDL) is a key factor in atherosclerosis development.
- Antioxidants are hypothesized to protect LDL from oxidative damage.
- The combined effects of beta-carotene, vitamin C, and alpha-tocopherol on LDL oxidation require further investigation.
Purpose of the Study:
- To investigate the impact of daily supplementation with beta-carotene, vitamin C, and alpha-tocopherol on LDL oxidation in humans.
- To determine if antioxidant supplementation alters the susceptibility of LDL to oxidation.
- To explore the relationship between plasma antioxidant concentrations and LDL oxidation parameters.
Main Methods:
- A 6-month supplementation study involving 22 subjects receiving daily doses of beta-carotene, vitamin C, and alpha-tocopherol.
- A control group of 23 subjects received no vitamin supplements.
- Measurement of plasma antioxidant concentrations, LDL oxidation rate, conjugated diene production, malondialdehyde levels, and lag time before LDL oxidation onset.
Main Results:
- Plasma concentrations of beta-carotene, alpha-tocopherol, and ascorbic acid significantly increased after 3 months of supplementation.
- No significant differences were observed in the rate of LDL oxidation or total conjugated diene production between supplemented and control groups.
- The lag time before LDL oxidation onset was significantly lengthened in the supplemented group after 3 and 6 months.
- A significant correlation was found between the change in lag time and the change in plasma alpha-tocopherol levels.
Conclusions:
- Daily supplementation with beta-carotene, vitamin C, and alpha-tocopherol effectively increases plasma antioxidant levels.
- While not affecting the overall rate of LDL oxidation, supplementation significantly delays the onset of oxidation.
- Alpha-tocopherol appears to play a crucial role in extending the lag time before LDL oxidation, suggesting a protective mechanism against early oxidative damage.