IIRC low levels of vitamin D have been observed amongst conservative/orthodox communities who have ‘high coverage’ dress codes.
That was quite a few years back now, so hopefully the public health campaign at the time has made supplemental vitamin D a normal part of life for anyone falling into that risk category.
It’s been hypothesised that the reason humans living in Europe developed lighter skin is to maximise the vitamin D available from less sunlight (not my area so I don’t know how credible the theory is, but it makes logical sense and would explain why black Britons and African Americans have fewer Vit D reserves than their white neighbours).
the likely explanation for the pigmentation genes is to maximize vitamin D synthesis, said paleoanthropologist Nina Jablonski of Pennsylvania State University (Penn State), University Park, as she looked at the poster’s results at the meeting. People living in northern latitudes often don’t get enough UV to synthesize vitamin D in their skin so natural selection has favored two genetic solutions to that problem—evolving pale skin that absorbs UV more efficiently or favoring lactose tolerance to be able to digest the sugars and vitamin D naturally found in milk. “What we thought was a fairly simple picture of the emergence of depigmented skin in Europe is an exciting patchwork of selection as populations disperse into northern latitudes,” Jablonski says. “This data is fun because it shows how much recent evolution has taken place.”
www.sciencemag.org/news/2015/04/how-europeans-evolved-white-skin#
If correct, at least this is something we can try and equalise through improved public health education and access to supplements (unlike the X chromosome explanation for why men are getting sicker than women).