Vitamin D has been associated with numerous diseases and is important for bones and muscle strength. The sources of vitamin D are dietary and endogenous. Shifts from the Arctic night to midnight sun influences endogenous production of vitamin D as does dietary transition in Greenland. Seasonal shifts in 25-hydroxyvitamin D (25-OHD) are 30%. In addition, dietary transition in Greenland has reduced 25-OHD intake to levels of concern in younger individuals. Disease pattern in Greenland mirrors those seen elsewhere, but there are indicators of genetic adaption to Arctic night and diet, which is discussed in this review.