Vitamin D

The Dietary Reference Intakes of USA and Canada has set recommendation amount of vitamin D to 15 µg/d in adults. After subtraction 7.5 µg/d with produced by sun shine, residual 7.5 µg/d is considered to be required in a day. Although it is considered that there are many factors to be considered, because there is not sufficient evidence to change the approximate amount in the Dietary Reference Intakes for Japanese 2010 edition, it remains 5.5 µg/d. In the Dietary Reference Intakes for Japanese 2010 edition, approximate amount has been set to 5.5 µg/d based on the median intake in 50-69 age group in the National Health and Nutrition Survey in 2005 and 2006. Although the guidelines for treatment and prevention of osteoporosis 2011 edition has recommended 10-20 µg/d, the Dietary Reference Intakes for Japanese has set approximate amount to 5.5 µg/d because further studies are required to apply the entire elderly.

There are few studies for comparison between vitamin D intakes and vitamin D concentrations in child. Therefore, the approximate amount of child has been set by extrapolating body surface area from 0.75 square of weight ratio based on the approximate amount of adult.

The approximate amount of vitamin D in infant has been set from point of view of prevention of rickets, not vitamin D concentration in human milk. Although American Academy of Pediatrics has set to 5 µg/d for prevention of rickets in guideline in 2003, they have set to 10 µg/d in 2008. The Dietary Reference Intakes for Japanese has set the approximate amount in 0-5 months infant at 5 µg/d because the 2008 guideline of the American Academy of Pediatrics is hard to achieve. In 6-11 months infant with enough sunshine, the approximate amount has been set to 5 µg/d, without enough sunshine, it has also been set to 5 µg/d because there are few evidence, respectively.

Vitamin D deficiency was not observed with 7.0 µg/d or more intake in pregnant. Therefore, the approximate amount of pregnant has been set to 7.0 µg/d. The approximate amount of lactation has been set to 8.0 µg/d, added 2.5 µg/d, that vitamin D concentration 3.0 µg/L is multiplied by standard mammals amount 0.78 L/d, to the approximately amount in adult, 5.5 µg/d.

The upper limit of the dietary reference of vitamin D has been revised in 2015 edition, especially, the upper limit in adult has been revised from 50 µg/d to 100 µg/d, then the upper limit in infant and child has been revised. The scientific evidence is insufficient in vitamin D.

Vitamin D is absorbed from diet and produced by ultraviolet light in the skin. The effect of vitamin D is to promote absorption of calcium and phosphorus from the intestine and vitamin D deficiency leads to hypocalcemia. Then the result of it is secondary hyperparathyroidism, rickets in infant, osteomalacia in adults and osteoporosis in elderly. The excess of vitamin D leads to hypercalcemia, renal dysfunction and calcification of soft tissue.

References: br>
The Dietary Reference Intakes for Japanese (2015 edition) Fat-soluble vitamin (pdf) br>
The Dietary Reference Intakes for Japanese (2010 edition) Vitamin D (pdf)