Stead N W, Leonard S, Carroll R
Am J Med Sci. 1985 Dec;290(6):228-33. doi: 10.1097/00000441-198512000-00002.
Although trace minerals are necessary constituents of enzymes, dietary requirements of these nutrients for the elderly are unknown. This study measured selenium balance in six dependent elderly men before and after five weeks daily administration of 200 micrograms organically-bound selenium; dietary selenium intake averaged 62.1 +/- 7 micrograms/day during both study periods. Selenium status was assessed not only chemically but also biologically as red cell and platelet glutathione peroxidase activities. Plasma selenium averaged 8.8 +/- 0.8 micrograms% (normal: 10 +/- 2 micrograms %) when intake derived from dietary sources alone and increased during medicinal supplementation to an average of 12.8 +/- 1.9 micrograms %. The rise in plasma selenium was not associated with an increase in red cell or platelet glutathione peroxidase activity. The effect of selenium supplementation on in vivo platelet aggregability was studied by measuring plasma levels of beta-thromboglobulin and platelet factor 4, two proteins secreted concomitant with aggregation. beta-thromboglobulin diminished 7.5 +/- 11.0 ng/ml and platelet factor 7.6 +/- 11.0 ng/ml during selenium supplementation despite no change in platelet glutathione peroxidase activity. These data support the concept that selenium nutritional status should be assessed not only by blood selenium content but also by selenium-dependent enzyme activity or selenium-dependent biologic effect.
尽管微量元素是酶的必要组成成分，但老年人对这些营养素的膳食需求量尚不清楚。本研究测定了6名依赖他人照料的老年男性在每日服用200微克有机结合硒五周前后的硒平衡情况；在两个研究阶段，膳食硒摄入量平均为62.1±7微克/天。不仅通过化学方法，还通过红细胞和血小板谷胱甘肽过氧化物酶活性从生物学角度评估硒状态。仅从膳食来源摄入硒时，血浆硒平均为8.8±0.8微克%（正常：10±2微克%），在药物补充期间增加至平均12.8±1.9微克%。血浆硒的升高与红细胞或血小板谷胱甘肽过氧化物酶活性的增加无关。通过测量β-血小板球蛋白和血小板因子4的血浆水平来研究补充硒对体内血小板聚集性的影响，这两种蛋白质在血小板聚集时会伴随分泌。在补充硒期间，β-血小板球蛋白减少了7.5±11.0纳克/毫升，血小板因子减少了7.6±11.0纳克/毫升，尽管血小板谷胱甘肽过氧化物酶活性没有变化。这些数据支持这样一种观点，即评估硒营养状况不仅应通过血液硒含量，还应通过硒依赖性酶活性或硒依赖性生物学效应来进行。
