Vitamin D in the Dietary Reference Intakes for Japanese (DRIs) 2020

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 deficiency, is a risk for various diseases including osteoporotic fracture. Previously, the basis of AI for VD was the prevention of rickets and osteomalacia, but was changed to the median intake of healthy subjects in DRIs 2005. Recent studies have shown, however, that VD deficiency/insufficiency is quite prevalent, and the above basis is considered inadequate. Then in DRIs 2020, AI was defined as the amount necessary for fracture prevention (15 μg/d) minus that possibly produced in Sapporo during winter in the skin by ultraviolet (5 μg/d). UL and AI for infants were revised in DRIs 2015. For the future DRIs, more clinical and epidemiological studies are urgently needed.