Whole Blood Selenium Level and Selenium Supplementation in Elite Sports: Effect on Thyroid Metabolism (Performance Fatigue) and Cellular Immune Function (Frequency of Infection)

ummary: Recurrent and serious infections, muscle damage and training or competition induced fatigue are the most common symptoms in elite sport demolishing optimal training results or prohibiting competition. Are selenium deficiency responsible for these symptoms in elite sport and will daily supplementation prevent them. Methods: In 107 elite athletes [male: 49 – female: 58 / soccer: 20 – field hockey: 60 – Olympics: 18 – tennis: 5 – motorsports (DTM-Formula1): 4] whole blood selenium was determined. In all elite athletes the symptoms performance fatigue and recurrent infections were correlated. 24 elite athletes, getting daily supplementation of 200μg selenomethionine for 3 months, whole blood selenium, thyreotropine (TSH), free trijodthyronine (fT3), free thyroxin (fT4) and WBC before and after supplementation were determined and the symptoms infections and performance fatigue were correlated. A Spearman-ranking coefficient of correlation, a chi-quadrat-test (²-Test) by Pearson and an independent t-test were used. p<0,05 was supposed to be significant, p<0,01 highly significant. Results: In 57% of all elite athletes (N=61/107) a whole-blood-selenium-deficiency (< 121 μg/l) was established, in average 117 ± 29.08 μg/l. In cases of young national player (U16/U18) whole blood selenium compared to national A player were poorly supplied [106.47 ± 29.71 μg/l vs. 123.23 ± 32.9 μg/l (p=n.s)]. Comparing the settings of selenium > 145μg/l vs. < 145μg/l in 61% performance fatigue [107.8 ± 25.53 μg/l vs. 177.8 ± 30.74 μg/l, OR=0.39, p=0.091] were less complained in the higher group while comparing the settings of selenium < 145μg/l vs. > 145μg/l infections were 1.75times more frequent [109.4 ± 20.77 μg/l vs. 164 ± 11.53 μg/l, OR=1.75, p=0.27] in the lower group. Daily substitution of 200μg selenomethionine improved whole blood selenium significantly (127.50 ± 16.52 μg/l before vs. 176.29 ± 18.01 μg/l after treatment, p=0.0001). WBC (6.72 ± 1.42 per nL before vs. 4.82 ± 0.73 per nL after supplementation, p=0.0001) and thyreotropine (1.88 ± 0.68 μU/ml before vs. 1.27 ± 0.51 μU/ml after supplementation, p=0.003) decreased significantly after 3 months of daily substitution with 200μg selenomethio-nine, while free trijodthyronine (3.11 ± 0.73 pg/ml before vs. 3.65 ± 0.74 pg/ml after supplementation, p=0.006) improved significantly. Female athletes significantly were more worse supplied with free trjodthyronine than the male athletes (female: 2.48 ± 0.33 pg/ml vs. male: 3.33 ± 0.71 pg/ml, p=0.006). Athletes recurrently suffered from infections were significantly worse supplied with whole blood selenium than athletes without infections (120.9 μg/l with infections vs. 134.4 μg/l without infections, p=0.051). Per increase in whole blood selenium of 10 μg/l, the TSH decreases significantly by 0.12μU/ml (p=0.009) and fT3 improves by 0.11 pg/ml (p=0.088). The selenium-induced improvement of fT3 leads to a significant reduction in TSH [increase in fT3 of 0.1 pg/ml lowers TSH by 0.2 μU/ml, p=0.009). At the same time, the leukocytes decrease significantly [increase in fT3 of 0.1 pg/ml lowers the leukocytes by 0.38per nL, p=0.002).A significant absolute risk reduction of 45.84% for recurrent infections (13/24 before vs. 2/24 after therapy, p=0.043) and of 58.34% for performance fatigue (16/24 before vs. 2/24 after therapy, p=0.227) were calculated. No toxic side effects were observed. Conclusion: Independent to the type of sports, deficiency of whole blood selenium in elite sports was observed. Daily selenium substitution can significantly reduce performance fatigue by optimizing thyroid function and recurrent infections by optimizing the cellular immune system. Randomized treatment trials over a whole season must show whether performance fatigue or recurrent infections can be avoided by daily and permanent selenium substitution.