Vitamin D’s Brain Benefits Only Emerge at Adulthood

Higher serum vitamin D levels do not boost academic performance in childhood….

The null findings from the UK study are in line with two other studies using data from the Third US National Health and Nutrition Examination Survey (NHANES III), published in 2007 and 2011, which found no association between total serum 25-hydoxyvitamin D and childhood cognitive function. 

Some mainly cross-sectional studies in adults have suggested such a link. It is possible, say the researchers of the new study that the positive association of vitamin D with cognitive function seen in adults “does not emerge until later in life or that the previous cross-sectional adult studies are due to reverse causality.”

Anna-Maija Tolppanen, PhD, Medical Research Council Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, United Kingdom, and colleagues concluded that, “Taken together, our findings do not support suggestions that children should have controlled exposure to sunlight, or vitamin D supplements, in order to increase academic performance.”

The 3171 participants in the study are from the Avon Longitudinal Study of Parents and Children (ALSPAC), a population-based prospective birth cohort from South West England.

As part of the study, serum 25-hydroxyvitamin D2 and D3 concentrations were measured at a mean age of 9.8 years. The children’s performance in English, math, and science on the General Certificates of Education exams (GCSE) was assessed between the ages of 13 and 14 years and again between the ages of 15 and 16 years.

The researchers say serum 25-hydroxyvitamin D3 concentrations (at age 7.6 to 11.8 years) were not associated with academic performance in English, math, or science at age 13 to 14 years or 15 to 16 years.

“Somewhat surprisingly,” they say, serum 25-hydroxyvitamin D2 concentrations were associated with worse performance in English at age 13 to 14 years (adjusted SD change per doubling in 25-hydroxyvitamin D2, -0.05; 95% confidence interval [CI], -0.08 to -0.01).

Higher serum 25-hydroxyvitamin D2 levels were also associated with worse academic performance at age 15 to 16 years. The adjusted odds ratio for obtaining 5 or more “A” to “C” GCSE grades was 0.91 (95% CI, 0.82 – 1.00).

The researchers caution, however, that the “unexpected inverse association” could be a chance finding or due to residual confounding.

Dr. Tolppanen and colleagues note in their article that the “increasing number of association studies suggesting that low levels of vitamin D are related to a wide range of health outcomes, including cognitive function, have resulted in calls for changes to public health guidance regarding extreme protection against UV exposure.”

“However, 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,” they conclude.

J Epidemiol Community Health. April 11, 2012