Vitamin D deficiency: A Public Health Issue in High- and Low-Income Countries or Just Hype?

Globally, there has been increasing attention being paid to the problem of micronutrient malnutrition, especially as contrary to previous thinking, it is not uniquely the concern of poor countries. While, in general, micronutrient deficiencies are certainly more frequent and severe among disadvantaged populations, they also present a public health problem in some industrialized countries. Vitamin D deficiency is a good example, as it is certainly prevalent in some upper-middle to high-income countries, arising due to a lack of ultraviolet B (UVB) sunshine availability for anything from 2 to 8 months of the year. Furthermore, current population dietary vitamin D intakes do not compensate for the lack of vitamin D synthesis in the skin during this "vitamin D winter" period. It has been suggested that micronutrient deficiencies (sometimes referred to as "hidden hunger") is a major public health problem in developing countries. Whether vitamin D deficiency is one of these hidden hunger component deficiencies is an important question and worthy of consideration. This short chapter will highlight data to suggest that vitamin D deficiency may be evident in vulnerable groups (women of child-bearing age, infants, and young children) within several, but certainly not all, lower-middle and low-income countries (LMICs), despite the fact that many of these countries are generally sun-rich locations for significant parts of the year. However, despite this ample UVB availability, vitamin D deficiency in these LMICs arises due to one or more underlying reasons, which include low exposure to this UVB-rich sunshine, skin pigmentation, air pollution, skin covering, and low vitamin D intakes. This chapter will highlight lessons learned from industrialized countries on how to address vitamin D deficiency via a foods-first approach, with consideration of their utility in LMICs.