title: 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.
abstract: 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.
  
  
  METHODS
  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 micro g. Fourteen subjects each were assigned randomly to daily dose groups of 0, 21, 35, 55, 79, 102, and 125 micro 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- micro g supplement, which indicated that 49 micro g/d could optimize it. GPX activity was optimized by 21 micro g (total ingestion: 35 micro 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 micro g Se/d as selenomethionine is postulated to allow full expression of selenoproteins in US residents. This trial was registered at clinicaltrials.gov as NCT00428649.
authors.affiliation: Sichuan Provincial Center for Disease Control and Prevention, Chengdu, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Xia
authors.forename: Kristina E
authors.initials: KE
authors.lastname: Hill
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Jiayuan
authors.initials: J
authors.lastname: Xu
authors.forename: Dingyou
authors.initials: D
authors.lastname: Zhou
authors.forename: Amy K
authors.initials: AK
authors.lastname: Motley
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Byrne
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Burk
mesh_terms: D000328:Adult; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D004311:Double-Blind Method; D005979:Glutathione Peroxidase / Q000097:blood*; D006801:Humans; D009751:Nutritional Requirements; D012643:Selenium / Q000097:blood* / Q000172:deficiency; D012645:Selenomethionine / Q000494:pharmacology*; D051149:Selenoprotein P / Q000097:blood*
chemical_list: D015415:Biomarkers; D051149:Selenoprotein P; D012645:Selenomethionine; D005979:Glutathione Peroxidase; D012643:Selenium