DIETARY IRON CONCENTRATION ALTERS LDL OXIDATIVELY THE EFFECT OF ANTIOXIDANTS

Low-density lipoprotein (LDL) cholesterol participates in the atherosc lerotic process only after oxidative modification (o-LDL). Persons wit h elevated body iron concentrations are at higher risk of atherosclero sis. Iron in vitro is capable of oxidizing LDL, but it is unknown whet her or not high dietary iron concentrations alter LDL in vivo. The aim of this study was, therefore, to investigate (i) whether dietary iron concentrations cause LDL-cholesterol oxidation and (ii) whether antio xidants can prevent such changes. Rats received diets differing only i n iron concentration: 35 mg/kg, 150 mg/kg or 300 mg/kg diet. A LDL-VLD L particle was isolated and the following parameters measured: malondi aldehyde and lipid hydroperoxide concentrations (as an indication for lipid peroxidation); alpha-tocopherol and retinol concentrations (as a ntioxidants); protein sulfhydryl and carbonyl concentrations (as an in dication of protein modification); agarose gel electrophoresis and cho lesterol/protein ratio. Dietary iron increased LDL-VLDL lipid peroxida tion (malondialdehyde and lipid hydroperoxide concentrations), protein modification (sulfhydryl concentration), agarose migration distance a nd band width as well as cholesterol/protein ratio. Increased quantiti es of dietary iron led to a higher degree of oxidative change in LDL-V LDL. Lipid peroxidation, as well as protein modification, occurred, su ggesting apoB changes. This was probably due to diminished antioxidant concentrations of alpha-tocopherol and beta-carotene. Antioxidant sup plementation (alpha-tocopherol and beta-carotene), however, prevented all the above changes and could be helpful in the prevention of athero sclerosis.