Consumption of thermally-oxidized sunflower oil by chicks reduces α-tocopherol status and increases susceptibility of tissues to lipid oxidation

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Abstract
The effect of heated sunflower oil consumption on α-tocopherol status, fatty acid composition and oxidative stability of chicken tissues was investigated. Chicks were fed on diets containing (g/kg): fresh sunflower oil (FSO) 40, heated sunflower oil (HSO) 40 or heated sunflower oil (40) supplemented with α-tocopheryl acetate (HSE) to a similar α-tocopherol concentration as the FSO diet. Concentrations of α-tocopherol in tissues of chicks fed on HSO and HSE were significantly lower than those of chicks fed on FSO. Significant correlations were observed between plasma α-tocopherol concentration and the α-tocopherol concentrations of other tissues (r< 0·67,P< 0·005) and between log plasma α-tocopherol and plasma thiobarbituric acid-reacting substances (TBARS) concentrations (r– 0·851,P< 0·001). The concentrations of TEARS in tissues of chicks fed on the various diets were generally very similar before stimulation of peroxidation with Fe–ascorbate. Susceptibility of tissues to Fe–ascorbate-induced lipid peroxidation was increased by feeding HSO. Supplementation with α-tocopheryl acetate reduced susceptibility tc lipid oxidation to varying degrees, depending on the tissue. The results suggest that chronic ingesrion of oxidized lipids may compromise free-radical-scavenging activityin vivoby depleting α-tocopherol in the gastrointestinal tract, or possibly in plasma and other tissues.