Positive Health Online

Abstract

RAVN-HAREN and COLLEAGUES, Department of Toxicology and Risk Assessment, National Food Institute, Technical University of Denmark, Morkhoj Bygade 19, 2860 Soborg, Denmark.  grh@food.dtu.dk researched the effects of selenium supplementation upon oxidative parameters.

Background

Increased Se intakes have been associated with decreased risk of cancer and CVD. Several mechanisms have been proposed, including antioxidant effects through selenoproteins, induction of carcinogen metabolism and effects on the blood lipid profile.

Methodology

In a 4 x 1 week randomised, double-blind cross-over study, healthy young men supplemented their usual diet with selenate, Se-enriched yeast, Se-enriched milk or placebo (Se dose was 300 microg/d for selenate and Se-enriched yeast, and about 480 microg/d for Se-enriched milk) followed by 8-week washout periods.

Results

All Se sources increased serum Se levels after supplementation for 1 week. The effect of the organic forms did not differ significantly and both increased serum Se more than selenate. Conversely, thrombocyte glutathione peroxidase (GPX) was increased in the periods where subjects were supplemented with selenate but not in those where they were given Se-enriched yeast or Se-enriched milk. We found no effect on plasma lipid resistance to oxidation, total cholesterol, TAG, HDL- and LDL-cholesterol, GPX, glutathione reductase (GR) and glutathione S-transferase (GST) activities measured in erythrocytes, GPX and GR activities determined in plasma, or GR and GST activities in thrombocytes. Leucocyte expression of genes encoding selenoproteins (GPX1, TrR1 and SelP), and of electrophile response element-regulated genes (GCLC, Fra1 and NQO1) were likewise unaffected at all time points following intervention.

Conclusion

Thrombocyte GPX is specifically increased by short-term selenate supplementation, but not by short-term supplementation with organic Se. Short-term Se supplementation does not seem to affect blood lipid markers or expression and activity of selected enzymes and a transcription factor involved in glutathione-mediated detoxification and antioxidation.

References

Ravn-Haren G, Bugel S, Krath BN, Hoac T, Stagsted J, Jorgensen K, Bresson JR, Larsen EH and Dragsted LO. A short-term intervention trial with selenate, selenium-enriched yeast and selenium-enriched milk: effects on oxidative defence regulation. British Journal of Nutrition. 99(4): 883-92. Apr 2008.