The tolerable upper intake level ( UL) for vitamin A in adults is set at 3,000 μg RAE/day. Overconsumption of preformed vitamin A can be highly toxic and is especially contraindicated prior to and during pregnancy as it can result in severe birth defects. Rich sources of provitamin A carotenoids include orange and green vegetables, such as sweet potato and spinach. (More information)Īnimal food sources rich in preformed vitamin A include dairy products, liver, and fish oils fortified cereals may also contain preformed vitamin A. Retinoic acid and analogs are used at pharmacological doses in the treatment of acute promyelocytic leukemia and various skin diseases. Further, high-dose vitamin A supplementation is widely recommended for children over six months of age when they are infected with measles while malnourished, immunodeficient, or are at risk of measles complications. Vitamin A prophylaxis appears to significantly reduce childhood mortality in regions at high risk of vitamin A deficiency. The recommended dietary allowance ( RDA) is 700 micrograms of retinol activity equivalents (μg RAE)/day for women and 900 μg RAE/day for men. Vitamin A deficiency is associated with an increased susceptibility to infections, as well as to thyroid and skin disorders. It is most prevalent among children and women of childbearing age. Vitamin A deficiency is a major cause of preventable blindness in the world. Vitamin A has important roles in embryonic development, organ formation during fetal development, normal immune functions, and eye development and vision. Vitamin A is involved in regulating the growth and specialization ( differentiation) of virtually all cells in the human body.
The three active forms of vitamin A in the body are retinol, retinal, and retinoic acid. Vitamin A is a generic term that refers to fat-soluble compounds found as preformed vitamin A (retinol) in animal products and as provitamin A carotenoids in fruit and vegetables. Bronchopulmonary dysplasia in preterm infants.
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