Characteristics of Vitamin D Concentration in Elite Israeli Olympic Athletes

The prevalence of vitamin D deficiency has been a growing concern in recent years. Vitamin D is important in many of the body's physiological systems, such as the musculoskeletal, cardiovascular and immune functions. A deficiency of vitamin D in athletes may negatively impact both muscle functions and recovery and, thus, affect performance and increase the risk of injury. Many studies assessed the prevalence of vitamin D deficiency in athletes; however, as of today, there are no official recommendations/protocols for screening vitamin D levels in athletes, and only a few studies were performed in male and female elite athletes (i.e., Olympic level), in different sport disciplines. We investigated the prevalence of vitamin D deficiency among athletes entering the Israeli Olympic team. A total of 761 samples of Vitamin D(OH)25 from 334 athletes were analyzed. For this analysis, we used the first test the athlete had performed when joining the Olympic team. The prevalence of vitamin D deficiency (<50 nmol/L, as defined by the Endocrine Society Committee) was investigated according to gender, types of sports and outdoor vs. indoor sports through the different seasons of the Israeli Olympic team athletes. Twenty-five athletes (7.5%) were diagnosed with vitamin D deficiency. One hundred and thirty-one athletes (39.2%) had insufficient levels of vitamin D (50-75 nmol/L). The highest incidence of vitamin D deficiency was found amongst gymnastics and combat sport athletes. A significant difference was also found in vitamin D concentration between seasons. Vitamin D average concentration in the winter was 74.1 nmol/L compared to 86.4 nmol/L in the Summer (p < 0.0005). Due to the importance of vitamin D to athletic performance and the high prevalence of deficiency and insufficiency, we suggest careful and frequent monitoring of groups at risk, including elite athletes, especially in susceptible sports and during the winter. Future studies are necessary to investigate the effectiveness of Vitamin D supplementation in athletes with low baseline vitamin D levels.