I wonder if there isn’t a need for a bit more definition around the term” Caucasian” in this specific context. I am a very light skinned redhead of Scottish and Irish descent. My good friend is a very dark skinned man of Sicilian descent. We are both considered caucasian. Growing up we would spend the summers outside and I would easily burn while he never did. I am certain I can out-produce almost anyone in terms of turning sunlight into vitamin D. I would wager that I can come close to overdosing on vitamin D with normal sun exposure.
Yup. My ancestry is Italian, German (PA Dutch mostly), Irish, Scottish, and other things in that order. I have a slightly olive-ish skin tone and I tan pretty dark, but nobody would mistake me for anything but a white guy. That said, I’ve met blacks (usually mixed), Asians, and Native Americans lighter skinned than me, so race isn’t the best descriptor for this study, probably just “skin tone” overall would be more useful.
I agree that there are various hues deemed Caucasian so it will come down to individuals. That's true as well for other groups.
My doctor presently has me on 50,000 IU of vitamin D a week.
FYI, here is the way I'm prescribed to take the pills:
* Cholecalciferol (Vit D3) 400 IU tab (Take two tablets by mouth daily)
* Ergocalciferol (Vit D2) 50,000 IU cap (Take two capsules by mouth every week)
We take 4,000 units per day and have not had a sniffle in a year.