Feeding of a low-zinc diet lowers the tissue concentrations of alpha-tocopherol in adult rats.

Abstract

Previous work has shown that a low dietary intake of zinc for a short duration significantly lowers the lymphatic absorption of alpha-tocopherol (alphaTP) in adult male rats. The present study investigated whether the nutritional status of zinc is critical in maintaining the tissue levels of the vitamin. One group of rats was fed an AIN-93G diet containing 3 mg zinc/kg (low zinc, LZ) and the other was fed the same diet but containing 30 mg zinc/kg (adequate zinc, AZ). Food intakes between groups were matched by feeding two meals per day. At 6 wk, the body weights (356+/-8 g) of LZ rats reached 98% those (362+/-10 g) of AZ rats. Feeding of the LZ diet for 6 wk significantly lowered the concentrations of both alphaTP and zinc in the liver, kidney, heart, testis, and brain. No consistent relationships between alphaTP and zinc concentrations were observed in other tissues such as spleen, lung, gastrocnemius muscle, and retroperitoneal fat tissues. The concentrations of alphaTP in the liver, testis, brain, spleen, heart, and kidney were significantly correlated with the tissue concentrations of zinc. The LZ diet slightly but significantly increased the total lipid contents (mg/g) of liver, kidney, heart, and spleen. However, the tissue levels of phospholipid (micromol/100 mg lipid) in the heart, lung, testis, and spleen were decreased significantly in LZ rats. These findings indicate that low zinc intake results in a pronounced decrease in the animal's alphaTP status under the conditions of matched food intakes, body weights, and feeding patterns. The lower tissue levels of alphaTP may explain in part the compromised antioxidant defense system and increased susceptibility to oxidative damage observed in zinc deficiency.