Depends on your ancestry. If a population is in a given area for more than about 500 years, the general skin tone of that population adjusts to maximize vit D production while minimizing skin damage, for the available sunlight in that area. There’s actually a mathematical formula somewhere for skin tone and average yearly sunlight. The exception is Inuit populations, who have historically gotten most of their vit D from fatty fish.
So, those of us whose ancestors came from northern latitudes are better adapted for living in the northern states. Provided we actually get out in the sun once in a while :p
This may have been a contributing factor for why black slavery wasn’t as predominant in the northernmost areas of North America or Europe. While I was doing research on this, I came across reports of African slaves imported to England, getting sick and dying rather quickly. The reports are centuries old so its hard to be sure, but I’m hypothesizing here that they suffered severe vitamin D deficiencies, which made them quite vulnerable to a number of things. Combine that with diseases they’d never encountered, they probably didn’t stand much of a chance.
All theory, of course. My time machine’s in the shop :p
"Sun exposure Most people meet their vitamin D needs through exposure to sunlight [5,31]. Ultraviolet (UV) B radiation with a wavelength of 290-315 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3 [9,32,33]. Season, geographic latitude, time of day, cloud cover, smog, skin melanin content, and sunscreen are among the factors that affect UV radiation exposure and vitamin D synthesis [33]. The UV energy above 42 degrees north latitude (a line approximately between the northern border of California and Boston) is insufficient for cutaneous vitamin D synthesis from November through February [5]; in far northern latitudes, this reduced intensity lasts for up to 6 months. In the United States, latitudes below 34 degrees north (a line between Los Angeles and Columbia, South Carolina) allow for cutaneous production of vitamin D throughout the year [27]."
http://ods.od.nih.gov/factsheets/vitamind.asp