Abstract
Dietary Reference Intakes for Japanese (DRIs) are revised every five years. In DRIs 2020, major revision has been made on vitamin D (VD). In DRIs, five indices are defined for nutrients; estimated average requirement (EAR), recommended dietary allowance (RDA), and adequate intake (AI）for the prevention of deficiency/insufficiency, tolerable upper intake level (UL) for avoiding excess intake, and tentative dietary goal for preventing life-style- related diseases (DG) for the primary prevention of life-style-related diseases. For VD, AI has been determined.
VD deficiency causes rickets and osteomalacia. VD insufficiency, milder than its deficiency, is a risk for various diseases including osteoporotic fracture. Previously, the basis of AI for VD was determined based on the prevention of rickets and osteomalacia, but the basis was changed to the median intake of healthy subjects in DRIs 2005. However, recent studies have shown that VD deficiency/insufficiency is prevalent, and the above basis is considered inadequate.
Then, the AI for VD was defined as the amount necessary for fracture prevention (15 μg /day) minus the amount produced in the skin by ultraviolet (5 μg /day) based on the amount possibly produced in Sapporo during winter. The UL and AI for VD in infants were revised in DRIs 2015.
For the determination of the DRIs for VD in the future, more clinical epidemiological studies are urgently needed.
