Vitamin D intake from food may prevent or improve
cognitive function
In this large population-based study recently
published in Neurology, researchers
highlight a growing interest in the literature exploring the role of vitamin D
as a neurosteroid hormone in the nervous system, and its influence in cognitive
function and/or neurodysfunction.Investigators note current research suggests
that vitamin D supplementation may be especially helpful to deficient elderly
patients, possibly maintaining or improving global cognitive function.Because no randomized controlled trials have
tested this possibility, the authors of this study suggested that before
conducting a supplement drug trial it is important to first assess whether
vitamin D from food – and not supplements - could be associated with cognitive
performance in the elderly.
Annweiler C. et al “hypothesized that high dietary
intake of vitamin D could protect against cognitive decline.”They tested their hypothesis among two groups
of older women participating in the Epide´miologie de l’Oste´oporose (EPIDOS)
cohort.A total of 5,596 women
participated, divided into two groups based on their baseline weekly vitamin D
intake from food (inadequate < 35 ug/wk & recommended ≥ 35 ug/wk).Intake was estimated based on a food
frequency questionnaire, and cognitive impairment was scored via a validated
mental state questionnaire.Sun
exposure, season, depression, education, age and many other potential
confounders were considered in the statistical analysis.Notably, women were excluded from the study
if they consumed vitamin D supplements in the previous 18 months.
Ruling out potential confounders, the central finding
of this study was that weekly vitamin D intake from food sources was
significantly associated with overall cognitive performance; women with
inadequate dietary intakes of vitamin D had a greater prevalence of cognitive
impairment.Among several explanations
the authors discuss, one explanation of the observed associations between
vitamin D intake and cognitive decline may have to do with the nature of
food.Citing two other studies, they
write, “Nutrition indeed integrates
complex interactive effects of many dietary constituents. Nutrients are not
consumed in isolation but rather as components of an overall diet, which is
precisely considered as a modifiable risk factor for cognitive decline.”
In order to establish causality and accurately
determine mechanisms of action Annweiler C. et al encourage prospective
nutrition studies and clinical trials “to
assess a direct effect of vitamin D intake on cognitive decline.”
Study: Annweiler, C. et al Neurology,
75; 1810-16 (2010)