What is Consider a Vitamin A?
Vitamin A is the name of a group of fat-soluble retinoids, including retinol, retinal, and retinyl esters. Vitamin A is involved in immune function, vision, reproduction, and cellular communication.
Vitamin A is critical for vision as an essential component of rhodopsin, a protein that absorbs light in the retinal receptors, and because it supports the normal differentiation and functioning of the conjunctival membranes and cornea.
Vitamin A also supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, kidneys, and other organs.
Retinol, also called vitamin A₁, is a vitamin in the vitamin A family found in food and used as a dietary supplement. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which results in xerophthalmia.
In this article, learn more about the types of vitamin A, what vitamin A does, and some good sources of it.
- Preformed vitamin A occurs in meat, fish, and dairy products.
- Provitamin A is present in fruits, vegetables, and other plant-based products.
- Retinol is the main active form of vitamin A in the blood. Retinyl palmitate is the storage form of the vitamin.
- Beta-carotene is a provitamin or a precursor of vitamin A that occurs in plants — especially dark-colored fruits and vegetables and oily fruits.
Beta-carotene is, in itself, an antioxidant, but the body can also convert it into vitamin A as needed.
Important health benefits of vitamin A.
Vitamin A contributes to various bodily and helps prevent a range of problems.
- Protects your eyes from night blindness and age-related decline.
- Heals infections, especially in the throat, chest, and abdomen
- Prevents follicular hyperkeratosis, which can lead to dry, bumpy skin
- Helps fertility issues
- Decreases delayed growth in children
- May lower your risk of certain cancers.
- Supports a healthy immune system.
- Reduces your risk of acne.
- Supports bone health.
- Promotes healthy growth and reproduction.
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.
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:
- organ meats, such as liver
- fatty fish, such as tuna and herring
Plant-based foods contain carotenoids, which are antioxidant forms of vitamin A. The body converts these into retinol as it needs.
A 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 RA:E is equal to
- 1 microgram (mcg) of retinol
- 12 mcg of beta-carotene from food
- 2 mcg of beta-carotene from supplements
- 3.33 international units of vitamin A
The recommended daily allowances of vitamin A by age are as follows:
- up to 6 months: 400 mcg
- 7–12 months: 500 mcg
- 1–3 years: 300 mcg
- 4–8 years: 400 mcg
- 9–13 years: 600 mcg
- 14+ years: 900 mcg for males and 700 mcg for females
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 the highest risk of deficiency include:
- preterm infants
- infants and children in developing countries
- pregnant and lactating people in developing countries
- people with cystic fibrosis
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:
- up to 3 years: 600 mcg per day
- 4–8 years: 900 mcg per day
- 9–13 years: 1,700 mcg per day
- 14–18 years: 2,800 mcg per day
- 19+ years: 3,000 mcg per day
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:
- changes in skin color
- peeling on the palms of the hands and soles of the feet
- cracked skin on the fingers
- allergic contact dermatitis
- ectropion, which affects the skins around the eyes
- dry lips, mouth, and nose, which can increase the risk of infection
- reduced sebum production
Long-term overuse can lead to:
- changes in bone formation
- high cholesterol levels
- liver damage
- nervous system changes leading to headaches, nausea, and vomiting
During pregnancy, consuming too much retinol can increase the risk of an infant being born with:
- cleft palate
- heart problems
- hydrocephalus, or water on the brain
- problems with the thymus gland, which produces white blood cells
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.
Another possible cause of vitamin A toxicity is the use of retinol-based medications. Isotretinoin (Accutane) is one such example. Doctors sometimes prescribed 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
Please let us know in the comments below.
- Are you aware of Vitamin A? If so, how do you prepare it?
- Does anyone in your family have a history of an illness who might be able to be helped by Vitamin A?
- Has your doctor suggested Vitamin A as part of your supplement for your health?
Information on this site is not intended to diagnose, treat, cure, or prevent any disease. We encourage you to do your own research. Seek the advice of a medical professional before making any changes to your lifestyle or diet.
Share This Post
AsYouEatSoAreYou.com likes to share. Please feel free to repost articles as long as you always link back to the original and credit the author. Thank you ever so much.