(11-04-10) Establishing optimal selenium status: results of a randomized, double-blind, placebo-controlled trial1,2,3,4

Rachel Hurst, Charlotte N Armah, Jack R Dainty, Dave J Hart, Birgit Teucher, Andrew J Goldson, Martin R Broadley, Amy K Motley and Susan J Fairweather-Tait

1 From the School of Medicine Health PolicyPractice University of East Anglia Norwich United Kingdom (RHSJF-T); the Institute of Food Research Norwich Research Park Colney Norwich United Kingdom (CNA DJH BT JRDAJG); the University of Nottingham Sutton Bonington Loughborough United Kingdom (MRB);the Department of Medicine Division of Gastroenterology HepatologyNutrition Vanderbilt University Medical Center Nashville TN (AKM).
2 The views expressed herein are those of the authors and do not necessarily reflect the views of the Food Standards Agency.
3 Supported by the Food Standards Agency (project N05059); the Institute of Food Research, University of East Anglia; and the National Institutes of Health (grant DK058763). Pharma Nord (Denmark) donated the placebo and the selenium-enriched yeast supplement tablets.
4 Address correspondence to R Hurst, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich, Norfolk NR4 7TJ, United Kingdom. E-mail: [email protected] .
Background: Dietary recommendations for selenium differ between countries, mainly because of uncertainties over the definition of optimal selenium status.
Objective: The objective was to examine the dose-response relations for different forms of selenium.
Design: A randomized, double-blind, placebo-controlled dietary intervention was carried out in 119 healthy men and women aged 50?64 y living in the United Kingdom. Daily placebo or selenium-enriched yeast tablets containing 50, 100, or 200 ?g Se ( 60% selenomethionine), selenium-enriched onion meals ( 66% -glutamyl-methylselenocysteine, providing the equivalent of 50 ?g Se/d), or unenriched onion meals were consumed for 12 wk. Changes in platelet glutathione peroxidase activity and in plasma selenium and selenoprotein P concentrations were measured.
Results: The mean baseline plasma selenium concentration for all subjects was 95.7 ? 11.5 ng/mL, which increased significantly by 10 wk to steady state concentrations of 118.3 ? 13.1, 152.0 ? 24.3, and 177.4 ? 26.3 ng/mL in those who consumed 50, 100, or 200 ?g Se-yeast/d, respectively. Platelet glutathione peroxidase activity did not change significantly in response to either dose or form of selenium. Selenoprotein P increased significantly in all selenium intervention groups from an overall baseline mean of 4.99 ? 0.80 ?g/mL to 6.17 ? 0.85, 6.73 ? 1.01, 6.59 ? 0.64, and 5.72 ? 0.75 ?g/mL in those who consumed 50, 100, or 200 ?g Se-yeast/d and 50 ?g Se-enriched onions/d, respectively.
Conclusions: Plasma selenoprotein P is a useful biomarker of status in populations with relatively low selenium intakes because it responds to different dietary forms of selenium. To optimize the plasma selenoprotein P concentration in this study, 50 ?g Se/d was required in addition to the habitual intake of 55 ?g/d. In the context of established relations between plasma selenium and risk of cancer and mortality, and recognizing the important functions of selenoprotein P, these results provide important evidence for deriving estimated average requirements for selenium in adults. This trial was registered at clinicaltrials.gov as NCT00279812.

Source: Am J Clin Nutr 91: 923-931, 2010

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