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Should Selenium Sell?

Should Selenium Sell?. Sheril Marek KINE 628 Summer 2013. What is Selenium?. Essential trace element Selenoproteins play a critical role: Reproduction Thyroid hormone metabolism DNA synthesis Protection from oxidative damage and infection

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Should Selenium Sell?

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  1. Should Selenium Sell? SherilMarek KINE 628 Summer 2013

  2. What is Selenium? • Essential trace element • Selenoproteins play a critical role: • Reproduction • Thyroid hormone metabolism • DNA synthesis • Protection from oxidative damage and infection • Best known for role in glutathione peroxidase (GSH-Px) enzyme system

  3. Free radicals and Oxidative Stress • Reactive Oxygen Species (ROS) • Chemically reactive molecules containing O2 • Superoxide anion, peroxide, hydroxyl radical • ROS form as a natural byproduct of cellular metabolism • Environmental stress  ROS levels can increase dramatically • Exercise • Combine with molecules such as DNA, fats, and proteins, converting them into free radicals that continue to react (chain-reaction) • Oxidative damage (stress)

  4. GSH-Px enzyme system Interaction • Antioxidants act as a defense system against free radicals

  5. Soleus (Type 1) 55% VO2max 65% VO2max GSH-Px and Exercise 75% VO2max Red Gastrocnemius (Type IIa) White Gastrocnemius (Type IIb) Powers et al. 1994

  6. Question? • Since GSH-Px activity is increased, is there an increased need for more selenium?

  7. Determining Selenium Status Margaritiset al. 1995

  8. Question? • Since plasma and erythrocyte GSH-Px activity has been shown to reach a plateau at certain plasma SE concentrations, is supplementation beneficial?

  9. Selenium Supplementation • With supplementation, limited evidence showing (1) • Decreases in oxidative stress • Improvements in antioxidant levels • Most research shows no significant benefits of supplementation (4) • The RDA is based on the maximization of GPx activity • “More is not necessarily better”- Dr. Riechman • Adequate amounts in diet and status not compromised by routine exercise training • Research in its infancy…

  10. NIH RDA and Food Sources

  11. Selenium Deficiency and Toxicity • Deficiencies • Keshan Disease- viral cardiomyopathy • Kashin-Beck’s Disease- osteoarthritis • Thyroid Disease • Cognitive decline • Muscle pain and weakness • Toxicity • Hair and nail brittleness • Myocardial infarction • Muscle tenderness • GI distress • Respiratory distress

  12. Take Home Message • Selenium is a cofactor for a major antioxidant enzyme system • Glutathione Peroxidase enzyme system • Inhibitory effects on muscle damage • Assistance of antioxidant function • Role in prevention of fatigue • Aid in recovery from exhaustive exercise • DOMS • Selenium deficiencies are rare • Athletes do not need selenium supplementation • Food First! 

  13. References • Dragan I, Dinu V, Cristea E, Mohora M, Ploesteanu E, Stroescu V. Studies regarding the antioxidant effect of selenium on top swimmers. Rev Roum Physiol. 1990; 27:15-20. • Margaritis I, Rousseau A, Hininger I, Palazzetti S, Arnaud J, Roussel A. Increase in selenium requirements with physical activity loads in well-trained athletes is not linear. Biofactors23(2005) 45-55. • Powers SK, Criswell D, Lawler J, J LL. Martin D, Herb RA, Dudley G. Influence of exercise and fiber type on antioxidant enzyme activity in rat skeletal muscle. Am J PhysiolRegulIntegr Comp PhysiolFebruary 1, 1994 266:(2) R375-R380 • Tessier F, Margaritis I, Richard MJ, Moynot C, Marconnet P. Selenium and training effects on the glutathione system and aerobic performance. Med Sci Sports Exerc. 1995 Mar;27(3):390-6.

  14. Questions?

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