Sandstead H H
Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston 77555-1109.
Am J Clin Nutr. 1995 Mar;61(3 Suppl):621S-624S. doi: 10.1093/ajcn/61.3.621S.
Early signs of toxicity of essential trace elements are important. Some trace elements are available over-the-counter (OTC) and/or are present at industrial waste sites. Physicochemically similar trace elements compete for ligands, impairing functions, which is exemplified by the zinc-copper antagonism described long ago by Van Campen, Hill and Matrone, and Klevay. Intestinal absorption of copper is inhibited by zinc. Thus risk of copper deficiency is increased when the molar ratio of zinc to copper (Zn:Cu) is high. As shown by experiments, copper deficiency can occur in humans. Manifestations include decreased erythrocyte copper-zinc superoxide dismutase, increased low-density-lipoprotein cholesterol, decreased high-density-lipoprotein cholesterol, decreased glucose clearance, decreased methionine and leucine enkephalins, and abnormal cardiac function. Calculation of a preliminary reference dose for OTC zinc that assumed high bioavailability and uncertain copper intakes established 9 mg as a safe amount for 60-kg adults.
必需微量元素的早期毒性迹象很重要。一些微量元素可通过非处方（OTC）获取和/或存在于工业废物场所。物理化学性质相似的微量元素会竞争配体，从而损害功能，范坎彭、希尔、马特罗内和克莱维很久以前描述的锌 - 铜拮抗作用就是例证。锌会抑制肠道对铜的吸收。因此，当锌与铜的摩尔比（Zn:Cu）较高时，铜缺乏的风险就会增加。实验表明，人类可能会出现铜缺乏。表现包括红细胞铜锌超氧化物歧化酶降低、低密度脂蛋白胆固醇升高、高密度脂蛋白胆固醇降低、葡萄糖清除率降低、蛋氨酸和亮氨酸脑啡肽降低以及心脏功能异常。在假设高生物利用度和不确定铜摄入量的情况下，对非处方锌初步参考剂量的计算确定，60公斤成年人的安全量为9毫克。
