Vitamin D deficiency can lead to
musculoskeletal diseases such as
rickets and
osteomalacia, but
vitamin D supplementation may also prevent extraskeletal diseases such as
respiratory tract infections,
asthma exacerbations,
pregnancy complications and premature deaths.
Vitamin D has a unique metabolism as it is mainly obtained through synthesis in the skin under the influence of sunlight (i.e., ultraviolet-B radiation) whereas intake by nutrition traditionally plays a relatively minor role. Dietary guidelines for
vitamin D are based on a consensus that serum
25-hydroxyvitamin D (25[
OH]D) concentrations are used to assess
vitamin D status, with the recommended target concentrations ranging from ≥25 to ≥50 nmol/L (≥10-≥20 ng/mL), corresponding to a daily
vitamin D intake of 10 to 20 μg (400-800 international units). Most populations fail to meet these recommended dietary
vitamin D requirements. In Europe, 25(
OH)D concentrations <30 nmol/L (12 ng/mL) and <50 nmol/L (20 ng/mL) are present in 13.0 and 40.4% of the general population, respectively. This substantial gap between officially recommended dietary reference intakes for
vitamin D and the high prevalence of
vitamin D deficiency in the general population requires action from health authorities. Promotion of a healthier lifestyle with more outdoor activities and optimal nutrition are definitely warranted but will not erase
vitamin D deficiency and must, in the case of sunlight exposure, be well balanced with regard to potential adverse effects such as
skin cancer. Intake of
vitamin D supplements is limited by relatively poor adherence (in particular in individuals with low-socioeconomic status) and potential for overdosing. Systematic
vitamin D food fortification is, however, an effective approach to improve
vitamin D status in the general population, and this has already been introduced by countries such as the US, Canada, India, and Finland. Recent advances in our knowledge on the safety of
vitamin D treatment, the dose-response relationship of
vitamin D intake and 25(
OH)D levels, as well as data on the effectiveness of
vitamin D fortification in countries such as Finland provide a solid basis to introduce and modify
vitamin D food fortification in order to improve public health with this likewise cost-effective approach.