Roberts D C, Samman S
Department of Biochemistry, University of Sydney, Australia.
J Nutr Sci Vitaminol (Tokyo). 1990 Oct;36 Suppl 2:S119-24. doi: 10.3177/jnsv.36.supplementii_s119.
Increased dietary zinc has been shown to reduce plasma total cholesterol in rabbits fed casein. However, the mechanism is not clear. The minerals associated with casein and soya protein are different and present in amounts which can alter the overall mineral composition of the diet. In particular, casein has a much higher ratio of zinc/copper than soy protein. Utilising a range of copper concentrations (2-80 micrograms/g diet) in 14 experiments with casein diets showed a linear relationship between the cholesterolaemic response and copper concentration (when both log transformed) in groups (n = 6) of rabbits fed for 12 weeks (r = -0.70, p less than 0.05). The lower the copper, the greater the response. In no case was the copper content deficient, indicating some interaction must be reducing its availability. Similar analysis utilising the range of zinc (10-125 micrograms/g) in the diets also showed an enhanced response at low intakes (r = -0.85, p less than 0.05). To elucidate the mechanism, 2 groups of rabbits were fed casein diets containing 21 and 68 mg zinc/kg diet for 12 weeks. Low density apolipoprotein B (LDL-apoB) turnover was carried out using 125I labelled LDL-apoB and data was fitted to the 2 pool model. The production of LDL-apoB was reduced in animals fed the higher dietary zinc. Zinc appears to act by enhancing the production of LDL-apoB in casein fed animals, perhaps by reducing the availability of copper.
已表明增加膳食锌可降低用酪蛋白喂养的兔子的血浆总胆固醇。然而，其机制尚不清楚。与酪蛋白和大豆蛋白相关的矿物质不同，其含量可改变饮食的整体矿物质组成。特别是，酪蛋白的锌/铜比值比大豆蛋白高得多。在14项使用酪蛋白饮食的实验中，利用一系列铜浓度（2 - 80微克/克饮食）表明，在喂养12周的兔子组（n = 6）中，胆固醇血症反应与铜浓度（经对数转换后）之间呈线性关系（r = -0.70，p < 0.05）。铜含量越低，反应越大。在任何情况下铜含量都不缺乏，这表明一定有某种相互作用在降低其利用率。对饮食中锌含量范围（10 - 125微克/克）进行的类似分析也表明，低摄入量时反应增强（r = -0.85，p < 0.05）。为阐明机制，两组兔子用含21和68毫克锌/千克饮食的酪蛋白饮食喂养12周。使用125I标记的低密度脂蛋白载脂蛋白B（LDL - apoB）进行低密度脂蛋白载脂蛋白B周转率测定，并将数据拟合到双池模型。喂食高膳食锌的动物中LDL - apoB的产生减少。锌似乎通过提高用酪蛋白喂养的动物中LDL - apoB的产生来起作用，可能是通过降低铜的利用率。
