I'll counter that with a quick quote from wikipedia: > Recommendations stemming for a single standard for optimal serum 25(OH)D concentrations ignores the diff

I'll counter that with a quick quote from wikipedia: > Recommendations stemming for a single standard for optimal serum 25(OH)D concentrations ignores the differing genetically mediated determinates of serum 25(OH)D and may result in ethnic minorities in Western countries having the results of studies done with subjects not representative of ethnic diversity applied to them. Vitamin D levels vary for genetically mediated reasons as well as environmental ones. Basically, rarely is anything simple enough for a "one size fits all" approach. Source: https://en.wikipedia.org/wiki/Hypervitaminosis_D https://en.wikipedia.org/wiki/Hypervitaminosis_D