6*. Iron overloading and the metabolism of D-α-tocopherol in the rat
Published online by Cambridge University Press: 09 March 2007
1. The effects of iron overloading and unsaturation of dietary lipid on the metabolism of α-tocopherol in the rat were studies.
2. Young adult male vitamin E-deficient rats were given 1000 i.u. of vitamin A and 100 μg of [14C-5-Me]D-α-tocopherol and then given diets containing 5% methyl oleate or 5% cod-liver oil fatty-acid methyl esters. Rats from each group were given intramuscular injections of iron-dextran (50 mg Fe/kg rat) at 48 h intervals for 15 days, and compared with controls given dextran. After this time, liver, kidney and the remainder of the carcass were analysed for [14C]α-tocopherol, and liver and kidney were also analysed for vitamin A.
3. There was no evidence that Fe overloading caused any increase in the destruction of either tocopherol or vitamin A in vivo, whether or not the diet contained polyunsaturated fatty acids. Indeed, treatment with Fe significantly decreased the metabolism of the radioactive tocopherol dose in all three tissues studied.
4. These experiments show that the stress effect of Fe in the vitamin E-deficient animal is unrelated to an increase in oxidative reactions. They provide further evidence that ‘lipid peroxidation’ is not causally concerned in ‘anti-vitamin E’ stress conditions and that α-tocopherol does not function, in vivo, as an antioxidant.