Vitamin A is a fat-soluble vitamin that is metabolized and stored by the fat in your body. Your vision and eye health rely heavily on vitamin A. Additionally, this vitamin plays a role in reproduction, cell division and differentiation, as well as bone growth. You can get all of the vitamin A you need from your diet or a multivitamin. Since vitamin A is stored, it's possible to consume too much and have toxic levels in your body.
Dosage of Vitamin A
Vitamin A is essential for your child's growth. For the first three years of life, your baby requires 300 mcg. Between the ages of 4 and 8, he needs 400 mcg, which increases to 600 mcg up until age 13. After the age of 14, women need 700 mcg of vitamin A daily, while men need up to 900 mcg, the Office of Dietary Supplements states. While you should stay within these guidelines, you can safely consume a little more than recommended. Your child can tolerate up to 600 mcg until she is 3 years old, 900 mcg between the ages of 4 and 8, and 1,700 mcg between ages 9 and 13. After age 14, the tolerable upper intake level for both women and men is 2,800 mcg.
Food Sources
Vitamin A from animal foods, known as preformed vitamin A, is easily absorbed and utilized in the form of retinol. Plant foods contain provitamin A carotenoids, which is important, but not as easily absorbed. Vitamin A is stored in the liver. Thus, eating liver provides large amounts of dietary vitamin A. Milk, cheese, eggs and yogurt are additional animal foods rich in vitamin A. Bright orange and green produce is loaded with this important vitamin. Carrots, kale, spinach, cantaloupe, apricots and mangoes are full of vitamin A.
Hypervitaminosis A
Vitamin toxicity is called hypervitaminosis A, which occurs by consuming too much preformed vitamin A from animal foods and not from carotenoids in plant foods. Preformed vitamin A is rapidly absorbed and stays in the body for an extended period of time, explains the Linus Pauling Institute. Acute toxicity occurs by consuming too much in a short amount of time, while chronic toxicity happens when you have high intakes over a long period of time. It is rare to have acute toxicity from vitamin A, but symptoms include fatigue, nausea and a headache caused by cerebral edema, which is excess fluid around the brain. Chronic hypervitaminosis A can have more severe effects such as desquamation, or peeling skin, liver damage, hemorrhage or possible coma.
Cancer Treatment
Very high doses of vitamin A can be prescribed to treat certain diseases. Retinoic acid, derived from vitamin A, can help with the treatment of acute promyelocytic leukemia, notes the Linus Pauling Institute. This type of cancer affects bone marrow and blood. While treatment with high dosages of vitamin A can improve symptoms and slow growth, it doesn't kill malignant cells.
Birth Defects
Having an excess of any of the compounds of vitamin A can cause birth defects if you're pregnant. Retinoids from vitamin A are long-acting and can cause complications in your pregnancy long after you stop taking a vitamin A treatment. Additionally, since vitamin A stays in your body for awhile, you should stop any vitamin A treatments long before you plan on becoming pregnant to avoid birth defects.
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