Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 1/7/2009
Publication Date: 4/27/2009
Citation: Jackson, M.I., Johnson, L.K., Hoeg, A., Hoefig, C., Davis, C.D., Milner, J.A., Schomburg, L., Combs, G.F. 2009. Components of Plasma Selenium in Healthy Americans. Journal of Federation of American Societies for Experimental Biology. 23:346.2
Technical Abstract: In a cohort of healthy adults (106 M, 155 W) in eastern North Dakota, we assessed the effects of supplementation with L-selenomethionine (SeMet) (0, 50, 100 or 200 mcg selenium [Se]/d for 1yr) on three plasma/serum biomarkers of Se status, which at baseline were: Se, 141.5±23.7 (SD) ng/ml; selenoprotein P (SePP), 3.55 (CI 2.61, 4.51) mg/l; glutathione peroxidase (GPX3) activity, 3.64±0.54 nmoles NADPH/min/mg. We imputed the portion of plasma Se present in selenocysteine (SeCys) in SePP and GPX3 from their known SeCys contents (5.5 and 4 g-atoms/mole), the molecular weights reported for each (57 kD and 92kD), and the enzyme number reported for purified GPX3 (2.8 x 104 nmoles NADPH/min/mg). This showed that prior to intervention 39.8±6.0 % of plasma Se occurred as SeCys, with the balance, 60.2±10.3 % comprised of other forms, presumably SeMet incorporated nonspecifically into various proteins. SeMet-supplementation did not affect the size of the SeCys component, but increased that of the non-specific component in a dose-dependent manner: baseline, 87.5±25.8 mcg/la; 12 mos.: 93.5±28.0a, 133.0±37.4b, 157.6±40.9c and 223.4±51d mcg/l for subjects receiving 0, 50, 100 or 200 mcg Se/day, respectively. Because SeMet is a dominant form of Se in foods, these results indicate that consumption of Se-containing foods by non-deficient individuals affects primarily the non-specific components of plasma Se.