Vitamin A is known as retinoids. Retinol, retinal, retinyl ester, β-carotene, α-carotene ,β-cryptoxanthin and 50 kinds of other carotenoids have vitamin A activity in the body. In the Dietary Reference Intakes for Japanese, retinol, β-carotene, α-carotene and β-cryptoxanthin are described. The unit of the dietary reference of vitamin A is retinol activity equivalent in 2015 edition and retinol equivalent in 2010 edition, respectively.
Vitamin A is substance that protects the retinal cells and is involved in the light stimulus reaction of the visual cell. Vitamin A deficient may lead to blindness from corneal xerosis in infants and night blindness in adults, respectively. And it may lead to growth inhibition, suppression of the development of bone and nervous system, disorders of differentiation and proliferation of epithelial cells, drying and thickening-keratinization of the skin, reduced immunity and susceptibility to infection due to drying of the mucosal epithelium.
Excessive intake of vitamin A may lead to cerebrospinal pressure rise and headache in the acute phase and intracranial hypertension, desquamation of the skin, hair loss and muscle pain in chronic phase, respectively.
| Gender | Male | Female | ||||||
|---|---|---|---|---|---|---|---|---|
| Age | Estimated Average Requirement | Recommended Amount | Approximate Amount | Upper Limit | Estimated Average Requirement | Recommended Amount | Approximate Amount | Upper Limit |
| 0-5 M | 300 | 600 | 300 | 600 | ||||
| 6-11 M | 400 | 600 | 400 | 600 | ||||
| 1-2 | 300 | 400 | 600 | 250 | 350 | 600 | ||
| 3-5 | 350 | 500 | 700 | 300 | 400 | 700 | ||
| 6-7 | 300 | 450 | 900 | 300 | 400 | 900 | ||
| 8-9 | 350 | 500 | 1200 | 350 | 500 | 1200 | ||
| 10-11 | 450 | 600 | 1500 | 400 | 600 | 1500 | ||
| 12-14 | 550 | 800 | 2100 | 500 | 700 | 2100 | ||
| 15-17 | 650 | 900 | 2600 | 500 | 650 | 2600 | ||
| 18-29 | 600 | 850 | 2700 | 450 | 650 | 2700 | ||
| 30-49 | 650 | 900 | 2700 | 500 | 700 | 2700 | ||
| 50-69 | 600 | 850 | 2700 | 500 | 700 | 2700 | ||
| 70- | 550 | 800 | 2700 | 450 | 650 | 2700 | ||
| Addition in First Trimester of Pregnancy | 0 | 0 | ||||||
| Addition in Second Trimester of Pregnancy | 0 | 0 | ||||||
| Addition in Third Trimester of Pregnancy | 60 | 80 | ||||||
| Addition in Lactation | 300 | 450 | ||||||
The intake of vitamin A required to maintain vitamin A in the liver is determined by compartment analysis using retinoid labeled with stable isotopes. Vitamin A excretion per 1 kg body weight in a day is 9.3 µg/kg/d, it is the required amount of vitamin A.
Estimated Average Requirement in adults, that is estimated from reference weight, are 550-600 µgRAE/d in male and 450-500 µRAE/d in female, respectively. The recommended amount, that is calculated from Estimated Average Requirement by multiplying recommended calculation coefficient 1.4, are 800-850 µgRAE/d in male and 650-700 µgRAE/d in female, respectively.
There are no reports about Estimated Average Requirement of vitamin A in child. Therefore, Estimated Average Requirement is calculated by extrapolating body surface area with 0.75 square of weight ratio. However, Estimated Average requirement in 5 years old or younger child is calculated based on vitamin A excretion per 1 kg weight in a day as 18.7 µg/kg/d. Recommended amount has been calculated based on Estimated Average Requirement by multiplying recommended amount calculated coefficient 1.4 as well as adult.
Most of the vitamin A is stored in the fetus in the last three months of gestation. Therefore, addition in first trimester and second trimester has been set to 0 and addition in third trimester has been set to 60 µgRAE/d, respectively. In lactation, to add vitamin A secreted in human milk, Estimated Average Requirement of addition has been set to 300 µgRAE/d. Recommended amount of addition has been multiplied by recommended amount calculated coefficient 1.4 and set to 450 µgRAE/d.
In 0-5 months infant, approximate amount has been multiplied vitamin A concentration in human milk 411 µgRAE/L by standard mammals amount 0.78 L/d and set to 300 µgRAE/d. Approximate amount of 6-11 months infant has been extrapolated from 0.75 square of weight ratio of 0-5 months infant and set to 400 µgRAE/d.
The upper limit have been set to 2700 µgRAE/d in adults, and 600 µgRAE/d in child, respectively. The upper limit in child has been extrapolated from weight ratio of the upper limit in adults.
References:
The Dietary reference Intakes for Japanese (2015 edition) Fat-Soluble Vitamin
The Dietary reference Intakes for Japanese (2010 edition) Vitamin A