Neither sunshine at recess nor a cup of milk at lunch will help students think better in class, even though high Vitamin D concentrations have been associated with better cognitive function in adults, according to a new study by the Journal of Epidemiology and Community Health.
Researchers analyzed the levels of two types of 25-hydroxyvitamin D—those associated with vitamin supplements and UVB sun exposure—and calcium in blood samples taken from 3,171 students in the Avon Longitudinal Study of Parents and Children when the children were about 10, 12 and 15 years old. They compared students' levels of vitamin D and calcium to their academic performance on national tests, the General Certificates of Education, taken at ages 13-14 and 15-16. They found no academic benefit for students with high levels of the nutrients, and actually found a decrease in academic achievement associated with high levels of the type of vitamin D associated with dietary supplements.
Prior studies have linked vitamin D to improved adult cognition, with research suggesting it may temper inflammation and affect genes that regulate brain plasticity, neurotransmitter function and differentiation, among other things. That, in turn led some to suggest protecting children from direct sun exposure could cause lower cognitive performance. That's a problem, considering that melanoma is an increasingly common cancer in children, but study author Anna-Maija Tolppanen, researcher with the MRC Center for Causal Analysis in Translational Epidemiology at the University of Bristol concluded, "Our results suggest that protection of children from UVB exposure, which has been associated with low levels of vitamin D, but which protects against skin damage and skin cancer, is unlikely to have any detrimental effect on academic achievement."
That's not to suggest, Tolppanen and her colleagues said, that vitamin D never improves cognition—it may simply have an impact only at adult phases of brain development or only after several decades' worth of exposure to the nutrients. Moreover, other studies still suggest that getting kids outside and playing can improve attention and class performance.
So educators can still encourage recess—just encourage sunscreen, too.