Importance of Vitamin A

Nishahameetha

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Vitamin A is a member of the fat-soluble family of vitamins that also includes vitamin D, vitamin E and vitamin K.

Vitamin A is important for normal vision, adequate growth, and for cell division and differentiation. Vitamin A is essential for immune system function because it is necessary for the production of white blood cells that help fight infections. You also need vitamin A for healthy skin and mucous membranes.

Vitamin A deficiency is rarely seen in developed countries, but can result in visual problems and loss of normal immune system function.

Daily Requirements


Males

1 to 3 years: 300 mcg per day
4 to 8 years: 400 mcg per day
9 to 13 years: 600 mcg per day
14+ years: 900 mcg per day

Females
1 to 3 years: 300 mcg per day
4 to 8 years: 400 mcg per day
9 to 13 years: 600 mcg per day
14+ years: 700 mcg per day

Vitamin A is found in both plant and animal sources. Preformed vitamin A, or retinol, is found in butter, egg yolks, fish, liver, meats and whole milk. Plant sources of vitamin A are called provitamin A carotenoids and include beta-carotene, alpha-carotene, and beta-cryptoxanthin. Carotenoids are found in dark green and yellow vegetables, as well as orange fruits and vegetables.

Taking vitamin A supplements, such as as beta carotene, has been recommended for preventing cancer; however, there is no evidence for this recommendation. In the case of cigarette smokers, taking beta carotene supplements may increase one’s risk of cancer.

Taking large doses of preformed vitamin A supplements for extended periods of time may result in vitamin A toxicity, so the Institute of Medicine determined tolerable upper levels to be 3000 mcg per day. Vitamin A toxicity may result in birth defects, liver abnormalities, and reduced bone mineral density that may result in osteoporosis.
 

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