Arthur J R
Rowett Research Institute, Bucksburn, Aberdeen, UK.
Proc Nutr Soc. 1999 May;58(2):507-12.
The micronutrient I, which has only one known biological function as a component of thyroid hormones, contrasts with Se, which is essential for many biochemical pathways through a range of Se-containing proteins. Thus, for I it is less complicated to propose and validate biochemical or functional markers which represent the adequacy or otherwise of dietary intake than it is to perform the same task for Se. Plasma thyroid-stimulating hormone provides a good indicator of functional I status, since levels of the hormone increase to compensate for any inadequacy in available dietary I. This increase occurs even when problems are caused by goitrogens restricting utilization of dietary I that otherwise would be adequate. In contrast, there are many potential indicators of Se status, especially since the many Se-containing proteins relate to different biochemical functions in the body. However, determination of the different GSH peroxidase (EC 1.11.1.9) activities in blood or tissue may give a useful indication of 'functional Se status', since these selenoproteins are often the most sensitive indicators of dietary Se intake. This approach has been successful in many experiments where animals of a similar genetic background have consumed diets which differ only in their Se content. Unfortunately, use of indicators of Se status in human populations may be complicated by differences (possibly genetic) between individuals that increase variability of selenoenzyme activities. The most appropriate indicator of functional Se status may also vary with other dietary conditions such as vitamin E or I deficiencies which may interact with Se deficiency. However, taking particular circumstances into account, determination of blood or tissue selenoprotein activity can provide a useful marker of adequacy of dietary Se supply for maintaining optimal health.
微量元素碘作为甲状腺激素的组成成分仅有一个已知的生物学功能，这与硒形成对比，硒通过一系列含硒蛋白对许多生化途径至关重要。因此，对于碘而言，提出并验证代表膳食摄入量充足与否的生化或功能标志物比针对硒执行相同任务要简单一些。血浆促甲状腺激素是功能性碘状态的良好指标，因为该激素水平会升高以补偿膳食碘供应的任何不足。即使问题是由致甲状腺肿物质限制膳食碘的利用（否则膳食碘是充足的）引起的，这种升高也会发生。相比之下，有许多潜在的硒状态指标，特别是因为许多含硒蛋白与体内不同的生化功能相关。然而，测定血液或组织中不同的谷胱甘肽过氧化物酶（EC 1.11.1.9）活性可能会给出“功能性硒状态”的有用指示，因为这些硒蛋白通常是膳食硒摄入量最敏感的指标。在许多实验中这种方法很成功，在这些实验中具有相似遗传背景的动物食用了仅硒含量不同的饮食。不幸的是，人群中硒状态指标的使用可能会因个体之间的差异（可能是遗传差异）而变得复杂，这些差异会增加硒酶活性的变异性。功能性硒状态的最合适指标也可能因其他膳食条件（如维生素E或碘缺乏）而异，这些条件可能与硒缺乏相互作用。然而，考虑到特定情况，测定血液或组织中的硒蛋白活性可以为维持最佳健康状况的膳食硒供应充足性提供有用的标志物。
