Do Professional Soccer Players have a Vitamin D Status Supporting Optimal Performance in Winter time

Background: Vitamin D is well known for its role in calcium homeostasis and bone metabolism. In addition 25 (OH) vitamin D3 (25OHD3) deficiencies is correlated with muscle pain and weakness, hence there is increasing interest in optimal 25OHD3 levels for athletes. We investigated the prevalence of 25OHD3 deficiency and the ethnical variation in 25(OH)D concentrations among professional soccer players in the winter season. Methods: Cross-sectional survey of 87 professional soccer players (aged 18-35) from one Belgian and two Dutch first division soccer clubs. Blood samples were collected from October 2009 till March 2010. 25OHD3 was measured using an electro-chemiluminescence immunoassay (Roche), reference interval: 50-130 nmol/L. Results: For 47 players (54%) of the total group the 25OHD3 was <50 nmol/L. For 16 subjects (18.4%) concentrations<30 nmol/L were found. All black players (n=20) had blood levels <50 nmol/L and 9/20 <30 nmol/L. In Latin-American players 10 out of 15 had 25OHD3 <50 nmol/L and 5/15 <30 nmol/L. For Caucasian players, 21/52 players were <50 nmol/L and 2/52 <30 nmol/L. Conclusion: The vitamin D level in professional soccer players at the end of the summer and during the winter season in West-Europe is obvious below optimal, for Caucasians 40% were deficient (<50 nmol/L), but all black athletes were deficient or severely deficient (<30). Especially dark skinned soccer players, as well as other athletes may improve their physical performance by keeping their 25OHD3 level above 75 nmol/L all year round.