Abstract/Summary

Hypovitaminosis D (vitamin D deficiency) is widespread throughout the world. The cutaneous production of vitamin D through sunlight can be limited by several factors (e.g. skin pigmentation, sunscreen usage and, increasingly, indoor lifestyle). Thus, diet has become an important strategy to increase vitamin D intake and status {blood 25-hydroxyvitamin D [25(OH)D]}. However, there are a limited number of foods that naturally contain vitamin D, and concentrations can vary significantly between and within species. The need for vitamin Dfortified foods (including via direct fortification and biofortification) to support the adequacy of vitamin D status is a corollary of several limitations to synthesise vitamin D from sunlight. Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) can be found in some mushrooms and animalderived foods, respectively. Evidence has shown vitamin D3 is more effective than vitamin D2 at raising 25(OH)D blood concentrations. The vitamin D metabolite, 25(OH)D3, is present in animal-derived foods (e.g. meat, eggs and fish), and several intervention trials have shown 25(OH)D3 to be more effective at raising blood 25(OH)D concentrations than vitamin D3. In addition, 25(OH)D3 supplements may prove to be preferable to vitamin D3 for patients with certain clinical conditions. However, there is limited evidence on the effects of 25(OH) D3-fortified foods on human vitamin D status and health, both in the general population and patients with certain conditions, and long-term randomised controlled trials are needed in this area.