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The following doses have been studied in scientific research:
ADULTS
BY MOUTH:
- General: The Recommended Dietary Allowance (RDA) levels for vitamin A are 900 mcg daily for men and 700 mcg daily for women. For women who are pregnant, the RDA is 770 mcg daily. For women who are breast-feeding, the RDA is 1,300 mcg daily.
The tolerable Upper Intake Level (UL) for vitamin A is 10,000 units (3,000 mcg) daily. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The UL for vitamin A is for preformed vitamin A (retinol) and does not include provitamin A carotenoids.
Vitamin A dosage is most commonly expressed in IU, but dosing in micrograms is sometimes used.
Eating 5 servings of fruits and vegetables per day provides about 50% to 65% of the adult RDA for vitamin A.
- For white patches inside the mouth that are usually caused by smoking (oral leukoplakia): Weekly dose of 200,000-300,000 IU of vitamin A has been used for 6-12 months.
- For complications after childbirth: Weekly doses of 23,000 IU of vitamin A have been used before, during, and after pregnancy. Weekly doses of 23,000 IU of vitamin A have been used before and during pregnancy.
- For ability to see in low-light conditions: Weekly doses of 23,000 IU of vitamin A have been used before, during, and after pregnancy. It seems to work best if taken in combination with 35 mg of zinc daily in women who also have low levels of zinc.
- For an inherited eye condition that causes poor night vision and loss of side vision (retinitis pigmentosa): Daily doses of 15,000 IU of vitamin A, sometimes along with 400 IU of vitamin E daily, has been used.
- A type of inflammatory bowel disease (ulcerative colitis): Vitamin A 25,000 IU daily has been used for 2 months.
CHILDREN
BY MOUTH:
- General: Recommended Dietary Allowance (RDA) levels of vitamin A are: birth to 6 months, 400 mcg/day; 7 to 12 months, 500 mcg/day; 1 to 3 years, 300 mcg/day; 4 to 8 years, 400 mcg/day; 9 to 13 years, 600 mcg/day; 14-18 years, 900 mcg/day. For girls 14-18 years of age who are pregnant, the RDA is 750 mcg. For girls 14-18 years of age who are lactating, the RDA is 1,200 mcg.
Tolerable Upper Intake Levels (UL) for vitamin A have also been established. The UL is the highest level of intake that is likely to pose no risk of harmful effects. The ULs for vitamin A are for preformed vitamin A (retinol) and do not include provitamin A carotenoids. For birth to 3 years, 600 mcg/day (2,000 units); 4 to 8 years, 900 mcg/day (3,000 units); 9 to 13 years, 1700 mcg/day (5,667 units); and 14 to 18 years, 2800 mcg/day (9,333 units).
- For measles: 100,000 to 200,000 IU of vitamin A for at least two doses has been used in children less than 2 years-old.
- For death of an unborn or premature baby: Vitamin A supplements are recommended for children 6-59 months of age who are at risk of vitamin A deficiency. For children ages 6-11 months, one dose providing 100,000 IU of vitamin A is recommended. For children ages 12-59 months, 200,000 IU of vitamin A every 4-6 months in recommended. *
Unit Conversion *
1 IU = 0.3 mcg retinol
1 mcg RAE = 1 mcg retinol
1 mcg RAE = 2 mcg supplemental beta-carotene
1 mcg RAE = 12 mcg beta-carotene
1 mcg RAE = 24 mcg alpha-carotene
1 mcg RAE = 24 mcg beta-cryptoxanthin
