Vitamin A
Vitamin A is key for good vision, a healthy immune system, and cell growth.
There are two types of vitamin A. This entry is primarily about the active form of vitamin A, retinoids, that come from animal products. Beta-carotene is among the second type of vitamin A, which comes from plants.
The American Heart Association recommends obtaining antioxidants, including beta-carotene, by eating a well-balanced diet high in fruits, vegetables, and whole grains rather than from supplements until more is known about the risks and benefits of supplementation.
High doses of antioxidants (including vitamin A) may actually do more harm than good. Vitamin A supplementation alone, or in combination with other antioxidants, is associated with an increased risk of mortality from all causes, according to an analysis of multiple studies.
Why do people take vitamin A?
Topical and oral retinoids are common prescription treatments for acne and other skin conditions, including wrinkles. Oral vitamin A is also used as a treatment for measles and dry eye in people with low levels of vitamin A. Vitamin A is also used for a specific type of leukemia.
Vitamin A has also been studied as a treatment for many other conditions, including cancers, cataracts, and HIV. However, the results are inconclusive.
Most people get enough vitamin A from their diets. However, a doctor might suggest vitamin A supplements to people who have vitamin A deficiencies. People most likely to have vitamin A deficiency are those with diseases (such as digestive disorders) or very poor diets.
How much vitamin A should you take?
The recommended dietary allowance (RDA) includes the vitamin A you get from both the food you eat and any supplements you take.
There are two types of vitamin A. This entry is primarily about the active form of vitamin A, retinoids, that come from animal products. Beta-carotene is among the second type of vitamin A, which comes from plants.
The American Heart Association recommends obtaining antioxidants, including beta-carotene, by eating a well-balanced diet high in fruits, vegetables, and whole grains rather than from supplements until more is known about the risks and benefits of supplementation.
High doses of antioxidants (including vitamin A) may actually do more harm than good. Vitamin A supplementation alone, or in combination with other antioxidants, is associated with an increased risk of mortality from all causes, according to an analysis of multiple studies.
Why do people take vitamin A?
Topical and oral retinoids are common prescription treatments for acne and other skin conditions, including wrinkles. Oral vitamin A is also used as a treatment for measles and dry eye in people with low levels of vitamin A. Vitamin A is also used for a specific type of leukemia.
Vitamin A has also been studied as a treatment for many other conditions, including cancers, cataracts, and HIV. However, the results are inconclusive.
Most people get enough vitamin A from their diets. However, a doctor might suggest vitamin A supplements to people who have vitamin A deficiencies. People most likely to have vitamin A deficiency are those with diseases (such as digestive disorders) or very poor diets.
How much vitamin A should you take?
The recommended dietary allowance (RDA) includes the vitamin A you get from both the food you eat and any supplements you take.
| Category | Vitamin A: Recommended Dietary Allowance (RDA) in micrograms (mcg) of Retinol Activity Equivalents (RAE) |
CHILDREN | |
| 1-3 years | 300 mcg/day (or 1,000 International Units/day) |
| 4-8 years | 300 mcg/day (or 1,000 International Units/day) |
| 9-13 years | 600 mcg/day (2,000 IU/day) |
FEMALES | |
| 14 years and up | 700 mcg/day (2,310 IU/day) |
| Pregnant | 14-18 years: 750 mcg/day (2,500 IU/day) 19 years and over: 770 mcg/day (2,565 IU/day) |
| Breastfeeding | Under 19 years: 1,200 mcg/day (4,000 IU/day) 19 years and over: 1,300 mcg/day (4,300 IU/day) |
MALES | |
| 14 years and up | 900 mcg/day (3,000 IU/day) |
The tolerable upper intake levels of a supplement are the highest amount that most people can take safely. Higher doses might be used to treat vitamin A deficiencies. But you should never take more unless a doctor says so.
| Category (Children & Adults) | Tolerable Upper Intake Levels (UL) of Retinol* in micrograms (mcg) of Retinol Activity Equivalents (RAE) |
| 0-3 years | 600 mcg/day (or 2,000 International Units/day) |
| 4-8 years | 900 mcg/day (3,000 IU/day) |
| 9-13 years | 1,700 mcg/day (5,610 IU/day) |
| 14-18 years | 2,800 mcg/day (9,240 IU/day) |
| 19 years and up | 3,000 mcg/day (10,000 IU/day) |
* There is no upper limit for vitamin A from beta-carotene.
Can you get vitamin A naturally from foods?
Half to 65% of the adult RDA for vitamin A is easily obtained simply by eating the recommended five servings of fruits and vegetables per day.
Good food sources of retinoid vitamin A include:
- Eggs
- Whole milk
- Liver
- Fortified skim milk and cereals
Plant sources of vitamin A (from beta-carotene) include carrots, spinach, and apricots.
What are the risks of taking vitamin A?
What are the risks of taking vitamin A?
- Side effects. Symptoms of vitamin A toxicity include dry skin, joint pain, vomiting, headaches, confusion.
- Interactions. If you take any medicines, ask your doctor if vitamin A supplements are safe. Vitamin A supplements may interact with some birth control pills, blood thinners (Coumadin), acne medicines (Accutane), cancer treatments, and many other drugs.
- Risks. Don't take more than the RDA of vitamin A unless your doctor recommends it. High doses of vitamin A have been associated with birth defects, lower bone density, and liver problems. People who drink heavily or have kidney or liver disease shouldn't take vitamin A supplements without talking to a doctor.
Post a Comment