Can the Vitamin D Needs of the North American Public Be Met By Current Supplementation and Fortification Practices in the Absence of Sun Exposure?

Vitamin D status is poorest in dark-skinned individuals where the high melanin content of their skin blocks sunlight and synthesis of vitamin D. Poor vitamin D status is associated with a much higher incidence and greater mortality from diabetes, breast and prostate cancer. In North America, Vitamin D status is also considered suboptimal in many light skinned individuals.

Sun exposure is an important source of vitamin D. Currently some medical experts insist that sun exposure should be restricted due to damaging effects of ultraviolet light (UV); at the same time they assume that the current diet is sufficient to meet the newly recognized higher needs for vitamin D in the absence of sun exposure. The dietary basis for this health policy recommendation has not been validated.

We evaluated current vitamin D intakes and examined efficacy of supplementation and food fortification in Canada and the United States National surveys. Mean vitamin D intakes from all sources are close to or below 5 µg, the Dietary Reference Intakes (DRI) recommended for persons 1 to 50 y, but now widely recognized as being too low to maintain adequate vitamin D status neither during the winter, nor in the elderly or darker skinned individuals year round. In establishing public health policy with regard to sun exposure, consideration must be given that neither fortification nor supplementation as currently practiced in North America allows all individuals in the general healthy population to meet their vitamin D needs in the absence of exposure to sunlight.