Dietary docosahexaenoic acid enhances ferric nitrilotriacetate-induced oxidative damage in mice but not when additional α-tocopherol is supplemented

Weaning mice were fed a diet supplemented with beef tallow (BT) or BT plus docosahexaenoic acid (DHA) containing 100 mg α-tocopherol/kg (α-Toc100) or 500 mg α-tocopherol/kg (α-Toc500) for 4 wk to modify membrane fatty acid unsaturation, and then were administered ferric nitrilotriacetate (Fe-NTA). The mortality caused by Fe-NTA was higher in the group fed the DHA (α-Toc100) diet than in the BT diet groups but the DHA (α-Toc500) diet suppressed this increase. Serum and kidney α-tocopherol contents were slightly influenced by the dietary fatty acids but not significantly. These results indicate that the increased unsaturation of tissue lipids enhances oxidative damage induced by Fe-NTA in mice fed DHA (α-Toc100) but not when additional α-tocopherol is supplemented. The apparent discrepancy between the observed enhancement by dietary DHA of oxidative damage and the beneficial effects of dietary DHA on the so-called free radical diseases is discussed in terms of strong bolus oxidative stress and moderate chronic oxidative stress.