Could this be why evidence suggests that redheads synthesize Vitamin D more efficiently? Red hair is more prevalent at higher latitudes (I think).
Can redheads produce Vitamin D in these darker conditions while others cannot do so effectively?
https://www.sciencealert.com/evolution-favored-genes-linked-...
Pale skin in general helps synthesize Vitamin D. The less melanin you have the more you absorb, this is why lighter skin happens at northern latitudes. Darker skinned people are more likely to need to supplement it.