The Prevalence and Risk Factors of Vitamin D Deficiency in Athletes in Kuwait
Vitamin D, obtained mostly from sunlight, is essential to maintain a healthy musculoskeletal system. A high prevalence of vitamin D deficiency has been found worldwide among the general population including sunny countries, and has been associated with several risk factors. Vitamin D plays an important role in athletes’ health and performance, but similar to the general population, there is a high prevalence of vitamin D deficiency among athletes worldwide. Despite the sunny weather in Kuwait, several studies showed a high prevalence of vitamin D deficiency in women and children. To our knowledge, no vitamin D study has been conducted on athletes in Kuwait. This study was undertaken to determine the prevalence of vitamin D inadequacy in male athletes living in Kuwait, and to assess the relationship between vitamin D and risk factors including lifestyle, body composition and the month of Ramadan; when Muslims fast daily from sunrise to sunset.
To further explore the relationship between vitamin D and body composition, a systematic review of observational studies was conducted to assess the effect of body fat on vitamin D levels in healthy adults. Additionally, a cross-sectional study was conducted on 250 healthy male athletes (≥ 21 years old) registered in one of the 16 official sports clubs in Kuwait. Data was collected between March and August 2015. Lifestyle assessment, anthropometric measurements and blood tests were performed and vitamin D levels below 75 nmol/l were considered inadequate.
The results of our systematic review suggest that there is an inverse association between vitamin D and body fat. However, results were inconclusive due to heterogeneity of the included studies. The findings of the cross-sectional study revealed a prevalence of 83% of vitamin D inadequacy (<75nmol/l) in athletes in Kuwait, of which 23% had severe deficiency (< 25 nmol/l). Median serum 25(OH)D was higher for samples taken before Ramadan than for those after. We found statistically significant positive associations between serum 25(OH)D concentrations and both dietary and prescribed high dose vitamin D intake. A statistically significant negative association was seen between 25(OH)D parathyroid hormone, overall incidence of injuries, and the month Ramadan. Contrary to our expectation, we did not find any significant associations between 25(OH)D concentrations and anthropometric measures, physical activity, sun exposure, symptoms, skin type or serum calcium.
In conclusion, athletes in Kuwait have a high prevalence of vitamin D inadequacy. Athletes who had a high intake of vitamin D from food or supplements were more likely to have adequate levels of vitamin D, while athletes with injuries were more likely to have inadequate levels of vitamin D. Vitamin D deficiency screening and health educational support are required to improve health and performance for athletes in Kuwait. Further studies are needed to explore the relationship between vitamin D status and athletes’ injuries and body composition.