Abstract
The influences of dietary lipids on zinc metabolism in rats fed diets containing either low (<1ppm), sub-optimal (10ppm) or adequate (25ppm) levels of zinc were examined. Serum alkaline phosphatase (APase) activity and zinc levels in the serum, distal small intestine (ileum) and femur were decreased in rats fed either a 5% corn oil-zinc deficient or a 5% beef tailow-zinc deficient diet containing 20% demineralized soybean protein compared with those of rats fed the respective zinc-adequate diets. However, there was no difference in these parameters between the two lipid groups. When rats were fed 20% protein diets containing 10ppm zinc, a 20% beef tallow diet caused increases in the serum and femur zinc levels campared with those of rats fed the 5% beef tallow diet, while no difference was observed between the groups fed 5% and 20% corn oil diets. Serum APase activity was increased by feeding the rats 20% corn oil and 20% beef tallow diets. Rats fed low-protein diets (10%) had higher serum and femur zinc levels and serum APase activity than rats fed 20% protein diets, and the difference in the femur zinc levels was increased between the groups fed the 20% omrn oil and 20% beef tallow diets. These results suggest that feeding rats on high-lipid diets affects their zinc metabolism, and that high bone zinc levels in rats fed a high-beef tallow diet are probably due to a lowered zinc requirement in the animals.
