Optimization of selenoprotein P and other plasma selenium biomarkers for the assessment of the selenium nutritional requirement: a placebo-controlled double-blind study of selenomethionine supplementation in selenium-deficient Chinese subjects

摘要

>Background: The intake of selenium needed for optimal health has not been established. Selenoproteins perform the functions of selenium, and the selenium intake needed for their full expression is not known.>Objective: This study sought to determine the intake of selenium required to optimize plasma selenoprotein P (SEPP1) and to compare SEPP1 with other plasma selenium biomarkers.>Design: A 40-wk placebo-controlled, double-blind study of selenium repletion was carried out in 98 healthy Chinese subjects who had a daily dietary selenium intake of 14 mu g. Fourteen subjects each were assigned randomly to daily dose groups of 0, 21, 35, 55, 79, 102, and 125 mu g Se as l-selenomethionine. Plasma glutathione peroxidase (GPX) activity, SEPP1, and selenium were measured. A biomarker was considered to be optimized when its value was not different from the mean value of the subjects receiving larger supplements.>Results: The SEPP1 concentration was optimized at 40 wk by the 35- mu g supplement, which indicated that 49 mu g/d could optimize it. GPX activity was optimized by 21 mu g (total ingestion: 35 mu g/d). The selenium concentration showed no tendency to become optimized.>Conclusions: The present results indicate that SEPP1 concentration is the best plasma biomarker studied for assessing optimal expression of all selenoproteins, because its optimization required a larger intake of selenium than did GPX activity. On the basis of the selenium intake needed for SEPP1 optimization with adjustments for body weight and individual variation, ap 75 mu g Se/d as selenomethionine is postulated to allow full expression of selenoproteins in US residents. This trial was registered at clinicaltrials.gov as .