Vitamin A is produced by your body from pigments such as beta-carotene, which is found in green leafy and yellow/orange vegetables or consumed directly as a supplement. Vitamin A is very important in maintaining healthy vision, immunity and gene expression during development. The recommended daily serving for adults is 3,000 IU for men and 2,300 IU for women. Children and pregnant or breast-feeding mothers have different requirements.
Identification
Vitamin A is used to produce the photopigment that allows your retinas to detect light and convert it into electrochemical signals that your brain can understand. Vitamin A is also essential for the maturation of immune cells in the blood and their response to infections. In children, vitamin A is needed for the orderly progression of gene expression, which drives development.
Adults
The recommended daily consumption of vitamin A for adults is easily achieved if you take a multivitamin that you can absorb well. These vitamins typically contain around 5,000 IU of vitamin A, which exceeds the recommended dose for men and women, leaving some room for incomplete absorption. If you do not take a multivitamin or are not sure if it is properly absorbed, dark colored vegetables, fish oil, eggs, milk, butter and fortified cereals are also good sources.
Children
Vitamin A is important for children to develop properly. Infants younger than six months old require 1,333 IU of vitamin A per day. Infants between six months and one year of age require 1,667 IU per day. Children between one and eight years require slightly less at 1,000 to 1,333 IU per day. Children 9 to 13 years old require 2,000 IU per day. Children 14 years or older require the adult dosage. Children are more susceptible to vitamin A toxicity, and should consume dark green and orange vegetables rather than relying only on a vitamin supplement.
Pregnant or Breast-Feeding
Women who are pregnant or breast-feeding require a higher daily intake of vitamin A, as they are consuming both for themselves and their child. Women require 2,500 IU per day during pregnancy. During breast-feeding, mothers require 4,000 to 4,333 IU per day. There is no separate recommendation for women with multiple children. These women should consult their doctor to ensure that both they and their children are receiving adequate vitamin A.
Toxicity
Vitamin A toxicity occurs only with direct consumption of vitamin A through a supplement, not from over-consumption of foods with the carotenoid pigments that are precursors to vitamin A. Toxicity in adults occurs at a persistent intake of greater that 10,000 IU daily. Children under three years of age are much more susceptible to vitamin A toxicity, and should not receive more than 2,000 IU per day.
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