Conclusion Despite the limitations of the current evidence , the prevalence of vitamin D inadequacy in athletes is prominent .
The risk significantly increases in higher latitudes , in winter and early spring seasons , and for indoor sport activities .
The prevalence of injuries in athletes is notable but its association with  vitamin D status is unclear .
Background Vitamin D is essential for maintaining optimal bone health .
The prevalence of vitamin D inadequacy in athletes is currently unclear .
Objective The objective of this study is to determine the prevalence of vitamin D inadequacy in athletes .
Serum 25(OH)D is measured to clinical ly determine vitamin D status .
Vitamin D deficiency in children in Jerusalem: the need for updating the recommendation for supplementation.
BACKGROUND Hypovitaminosis D is common worldwide , even in sunny regions . OBJECTIVES To assess the prevalence and determinants of vitamin D deficiency in toddlers . METHODS A cross-sectional prospect i ve study was conducted in healthy Jewish children aged 1.5 - 6 years at five primary care pediatric clinics in the Jerusalem area during the period October 2009 to November 2010 . Parents were interviewed regarding personal and demographic data and sun exposure . Blood sample s were obtained for serum 25-hydroxyvitamin D [ 25-OHD ] level . Vitamin D deficiency and insufficiency were defined as 25-OHD < 20 ng/ml and < 30 ng/ml , respectively . RESULTS Of 247 children studied , 188 ( 76 % ) were ultra-Orthodox and 59 ( 24 % ) were Orthodox , traditional or secular . Mean ( + /- SD ) 25-OHD level was 25.7 + /- 10 ng/ml . Only 73 children ( 29.6 % ) had sufficient 25-OHD levels , 104 ( 42.1 % ) had insufficiency , and 70 ( 28.3 % ) had 25-OHD deficiency . The difference between ultra-Orthodox and others was insignificant ( 25 + /- 10 vs. 27.8 + /- 10.5 ng/ml respectively , P = 0.062 ) . Children aged 1.5 - 3 years had higher 25-OHD levels than those aged 3 - 6 years ( 28.6 + /- 10.7 and 24 + /- 9.2 ng/ml respectively , P < 0.001 ) . Vitamin D deficiency was more common in winter ( 53 % ) and autumn ( 360 % ) than in summer ( 19 % ) and spring ( 16 % ) . Toddlers attending long-day kindergartens had higher 25-OHD level than those staying at home or at short-day kindergartens ( 28.8 + /- 11.5 and 24.7 + /- 9.6 ng/ml respectively , P < 0.05 ) . CONCLUSIONS A high prevalence of vitamin D deficiency was found in toddlers in our study , mainly in older children and in the winter and autumn . We recommend routine supplementation of vitamin D for children beyond the age of one year
Conclusion Despite the limitations of the current evidence , the prevalence of vitamin D inadequacy in athletes is prominent .
The risk significantly increases in higher latitudes , in winter and early spring seasons , and for indoor sport activities .
The prevalence of injuries in athletes is notable but its association with  vitamin D status is unclear .
Background Vitamin D is essential for maintaining optimal bone health .
The prevalence of vitamin D inadequacy in athletes is currently unclear .
Objective The objective of this study is to determine the prevalence of vitamin D inadequacy in athletes .
Serum 25(OH)D is measured to clinical ly determine vitamin D status .