Vitamin D: Insufficiency, Uncertainty and Achievability.

Vitamin D is a prohormone that is essential to good health. As very few foods (fish, egg yolks, milk) are rich in vitamin D, the main source of the vitamin is synthesized in the skin in the presence of ultraviolet B rays from sunlight. However, due to Canada's northern latitude, sufficient amounts of vitamin D cannot be synthesized using sunlight during the fall and winter months and, consequently, there is a concern that many Canadians are not achieving adequate levels of vitamin D. A wide array of inconsistent evidence derived from serum and dietary assessments has been published and the results are inconclusive. This paper serves to outline the issues and challenges regarding nationwide intervention strategies such as fortification to increase vitamin D intake in the Canadian population. Given the potential for excessive intakes and the lack of informed Canadian data, implementing an intervention to increase vitamin D intake in the entire population may be irresponsible; however, further investigation of vitamin D intakes in certain subgroups of the Canadian population is warranted.