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Vitamin A is an essential vitamin that the body needs for growth and development. It is also vital for cell recognition, vision, immune function, and reproduction.
It also helps the heart, lungs, kidneys, and other organs function correctly.
Vitamin A deficiency is rare in the United States. If it happens, it can lead to eye problems, including night blindness.
In this article, learn more about the types of vitamin A, what vitamin A does, and some good sources of it.
Vitamin A occurs in different forms. The list below will provide more detail.
Beta-carotene is, in itself, an antioxidant, but the body can also convert it into vitamin A as needed.
Vitamin A contributes to various bodily functions and helps prevent a range of problems, including:
Consuming an adequate amount of vitamin A may have the following benefits.
Lower cancer risk
Some experts have looked at whether or not adequate intakes of carotenoids can help reduce the risk of lung, prostate, and other types of cancer.
However, research has produced mixed results.
Healthful skin and hair
Vitamin A is important in the growth of all bodily tissues, including skin and hair.
It contributes to the production of sebum, which is the oil that helps maintain levels of moisture in the skin and hair.
For more in-depth resources about vitamins, minerals, and supplements, visit our dedicated hub.
The form of vitamin A will depend on the source.
For example, ready-made retinol — which is the active form of vitamin A — only comes from animal sources.
The richest sources of retinol include:
Plant-based foods contain carotenoids, which are antioxidant forms of vitamin A. The body converts these into retinol as it needs.
Carotenoid is an orange pigment that contributes to the color of certain fruits and vegetables.
Fruit and vegetable sources that are rich in carotenoids are often orange. They include:
Plant foods that are rich in beta-carotene include dark green leafy vegetables, such as:
The recommended intake of vitamin A varies according to age. People also need more during pregnancy and while breastfeeding.
It is available in several forms, and the vitamin A content in foods is often measured as retinol activity equivalents (RAEs).
One RAE is equal to:
The recommended daily allowances of vitamin A by age are as follows:
During pregnancy, the requirement is 770 mcg per day. While breastfeeding, it is 1,300 mcg per day.
The 2007–2008 National Health and Nutrition Examination Survey found that the average U.S. individual, aged 2 years and above, consumes 607 mcg of vitamin A per day.
Who is at risk of deficiency?
Those at highest risk of deficiency include:
People who use the weight loss drug orlistat may have a higher risk of deficiency. Orlistat reduces the body’s ability to absorb fat soluble vitamins such as vitamin A.
Vitamin A supplements are available for those whose bodies have difficulty absorbing the nutrient, but it is best to meet needs through food, where possible.
This is because the use of supplements can mask possible deficiencies of other nutrients. This may lead to further health issues.
Preformed vitamin A can be toxic when people consume too much, either through their diet or through supplementation.
The tolerable upper intake level for vitamin A varies by age. The upper intake level is the amount above which vitamin A intake may be toxic.
The list below details the upper intake levels for preformed vitamin A by age:
It does not appear that a person can consume too much beta-carotene, as the body will only convert it into vitamin A as necessary.
Vitamin A toxicity
That said, consuming too much preformed vitamin A can lead to vitamin A toxicity, or hypervitaminosis A.
Symptoms can include:
Long-term overuse can lead to:
During pregnancy, consuming too much retinol can increase the risk of an infant being born with:
The use of the topical treatment retinol may also increase vitamin A levels to an unhealthy level. People tend to use retinol as an anti-aging skin cream.
Topical products can have adverse effects on the skin, though these will likely be less severe than those resulting from oral overconsumption. However, people should avoid using them during pregnancy.
The highest risk of overconsumption is with supplements. A healthful, balanced diet is unlikely to lead to toxic levels of vitamin A. It should also provide enough vitamin A without needing supplements.
Isotretinoin
Another possible cause of vitamin A toxicity is the use of retinol-based medications. Isotretinoin (Accutane) is one such example. Doctors sometimes prescribe isotretinoin for severe acne.
Anyone using this treatment should avoid taking vitamin A supplements because this drug is a vitamin A derivative.
A doctor will not prescribe isotretinoin if a person is pregnant or may become pregnant.
Vitamin A is an essential nutrient that contributes to many functions in the body, such as protecting eye health.
In the U.S., deficiency is rare. Most people can meet their needs for vitamin A through their diet.
In some cases, however, a doctor may recommend supplements. Anyone who uses vitamin A supplements should take care to follow the doctor’s instructions, as some forms of vitamin A can be toxic in high doses.
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