title: Vitamin D status and determinants of deficiency in non-supplemented athletes during the winter months in Tunisia.
abstract: Recent reports suggest that hypovitaminosis D in athletes is as common as in the general population. This study was devised to examine vitamin D status and determinants of deficiency in athletes living in a sunny country (Tunisia). One hundred and fifty national elite athletes, training outdoors (n = 83) or indoors (n = 67), were enrolled from January to February 2012. Plasma 25-hydroxyvitamin D was measured by radioimmunoassay. Concentrations were between 50 and 75 nmol · l(-1) in 21.3% of participants, between 25 and 50 nmol · l(-1) in 55.3% of participants and <25 nmol · l(-1) in 14.7% of participants. The concentrations were significantly lower in indoor athletes than outdoor athletes (36.2±19.0 nmol · l(-1) vs. 49.1±19.2 nmol · l(-1); p < 0.001). In multivariate analysis, vitamin D deficiency (25-hydroxyvitamin D <50 nmol · l(-1)) was associated with indoor sports [multi-adjusted odds ratio (95% confidence interval), 5.03 (1.64-15.4); p = 0.005], female gender [3.72 (1.44-9.65); p = 0.007] and age < 18 years [2.40 (1.01-5.85); p = 0.05]. Athletes living in sun-rich environments are exposed to a high risk of vitamin D inadequacy. Given the importance of vitamin D in health and athletic ability, targeting sufficient levels of plasma 25-hydroxyvitamin D in athletes is well justified.
authors.affiliation: Tunisian Research Laboratory ''Sport Performance Optimisation'', National Center of Medicine and Science in Sports, Tunis, Tunisia ; Laboratory of Biochemistry, Rabta Hospital, Faculty of Medicine of Tunis, El Manar University, Tunis, Tunisia.
authors.forename: A
authors.initials: A
authors.lastname: Sghaier-Ayadi
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Faculty of Medicine of Tunis, El Manar University, Tunis, Tunisia.
authors.forename: M
authors.initials: M
authors.lastname: Feki
authors.affiliation: Tunisian Research Laboratory ''Sport Performance Optimisation'', National Center of Medicine and Science in Sports, Tunis, Tunisia.
authors.forename: I Bezrati-Ben
authors.initials: IB
authors.lastname: Ayed
authors.affiliation: Tunisian Research Laboratory ''Sport Performance Optimisation'', National Center of Medicine and Science in Sports, Tunis, Tunisia.
authors.forename: O
authors.initials: O
authors.lastname: Abene
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Faculty of Medicine of Tunis, El Manar University, Tunis, Tunisia.
authors.forename: Mk Ben
authors.initials: MB
authors.lastname: Fredj
authors.affiliation: Laboratory of Biochemistry, Rabta Hospital, Faculty of Medicine of Tunis, El Manar University, Tunis, Tunisia.
authors.forename: K
authors.initials: K
authors.lastname: Kaabachi
authors.affiliation: Tunisian Research Laboratory ''Sport Performance Optimisation'', National Center of Medicine and Science in Sports, Tunis, Tunisia ; AUT University, Sports Performance Research Institute New Zealand, Auckland, New Zealand.
authors.forename: A
authors.initials: A
authors.lastname: Chaouachi
keywords: cholecalciferol; hypovitaminosis D; sun exposure; vitamin D inadequacy