Vitamin D status and measures of cognitive function
But also be aware that cognitive function is directly related to vitamin D status. Older folk with higher 25(OH)D status make fewer mental errors than do those with low status.
In the UK it takes over 5000iu/daily to stay above 100nmol/l throughout the year and gives you a safety zone before you drop below 80nnmol/l.
Average UK 25(OH)D remains lower than is safe throughout the year for maintaining optimum cognitive function