Despite long sunlight hours in the Middle East, indigenous women have been shown to experience low vitamin D levels, generally considered as a consequence of the cultural norm of keeping the skin covered.1 However, vitamin D deficiency is also endemic (91%) in Middle Eastern sportsmen with a more marked deficiency in the youngest adult.2 Historical literature suggests that ultraviolet light and vitamin D may have a role in optimising athletic performance,3 but there is limited evidence to support this hypothesis as a 1-year prospective trial of vitamin D3 supplementation did not increase grip strength in Lebanese adolescents.4

To assess vitamin D deficiency in adolescent Qatari girls …