title: An estimation of selenium requirements for New Zealanders.
abstract: BACKGROUND
  Current US dietary recommendations for selenium are based on maximization of plasma glutathione peroxidase (GSHPx) activity according to data from one study of Chinese men.
  
  
  OBJECTIVE
  The effect of various amounts of supplemental selenium on GSHPx activities in blood of New Zealand adults was investigated to calculate a selenium requirement for New Zealanders. The effect on plasma selenoprotein P and thyroid hormones was also investigated.
  
  
  METHODS
  Fifty-two adults with low blood selenium concentrations ingested a placebo or 10, 20, 30, or 40 microgram Se as L-selenomethionine daily for 20 wk.
  
  
  RESULTS
  Plasma and whole-blood GSHPx activities increased in all supplemented groups but reached a plateau only in the group receiving 40 microgram Se, as determined by statistical analysis. Increases in selenoprotein P were greater than those for selenium and GSHPx at all supplement intakes. Thyroxine concentrations decreased in supplemented groups but the decrease was significantly different from that in the control group only for the 10-microgram group and for all supplemented groups combined.
  
  
  CONCLUSIONS
  An upper estimated requirement of 90 microgram Se/d was calculated as the intake necessary for maximization of plasma GSHPx activity, as used in the derivation of the US recommended daily allowance. Our lower estimated requirement of 39 microgram Se/d was the intake necessary to reach two-thirds of maximal GSHPx activity, as was used in calculating the World Health Organization normative requirement. The lower estimate is a realistic goal for New Zealand but the upper estimate could be achieved only with regular inclusion of high-selenium foods.
authors.affiliation: Department of Human Nutrition, University of Otago, Dunedin, New Zealand.
authors.forename: A J
authors.initials: AJ
authors.lastname: Duffield
authors.forename: C D
authors.initials: CD
authors.lastname: Thomson
authors.forename: K E
authors.initials: KE
authors.lastname: Hill
authors.forename: S
authors.initials: S
authors.lastname: Williams
mesh_terms: D000328:Adult; D004311:Double-Blind Method; D005260:Female; D005979:Glutathione Peroxidase / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D018673:Nutrition Policy; D009751:Nutritional Requirements; D011506:Proteins / Q000378:metabolism*; D011863:Radioimmunoassay; D012643:Selenium / Q000008:administration & dosage* / Q000097:blood*; D051149:Selenoprotein P; D051140:Selenoproteins; D013974:Thyroxine / Q000097:blood
chemical_list: D011506:Proteins; D051149:Selenoprotein P; D051140:Selenoproteins; D005979:Glutathione Peroxidase; D012643:Selenium; D013974:Thyroxine