Vitamin A
Vitamin A is the group of fat-soluble nutrient compounds including retinol, retinal, and retinyl esters that are found in animals as well as plants. It’s stored in body tissue for later use. Most vitamin A kept in our liver in the form of retinyl esters. These esters are then broken down into all-trans-retinol, which binds to retinol-binding protein (RBP). It then enters your bloodstream, at which point your body can use it
There are two types of vitamin A found in foods:-
Preformed vitamin A (retinol and retinyl esters) that occurs only in animal products, such as dairy, liver, and fish
Provitamin A(carotenoids) are abundant in plant foods like fruits, vegetables, and oils.
To use them, our body must convert both forms of this vitamin to retinal and retinoic acid, the active forms of the vitamin.
Sources of Vitamin A
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The function of vitamin A
- It’s play important role in vision: Retinal, the active form of vitamin A, combines with the protein opsin to form rhodopsin, a molecule necessary for color vision and low-light vision that helps protect and maintain the cornea
- Immunity function: It supports immune function by supporting the growth and distribution of T-cells, a type of white blood cell that protects your body from infection.
- Supporting the cell growth: It helps to maintain healthy skin and the surface tissues such as your skin, intestines, lungs, bladder, and inner ear.
- Reproduction and fetal development: It play important role in reproduction such as the development of sperms and ovaries. It helps fetal tissue development and maintenance, as well as fetal growth.
Deficiency of vitamin A
- Blindness: The deficiency of this creates the blindness problem because lack of rhodopsin, a molecule necessary for color vision and low-light vision. Hence, always take the proper amount of this vitamin for healthy vision.
- Increased infection risk: The deficiency of this causes lower development of T-cell, which play a central role in immune responses that guard against disease. Therefore, this deficiency may create increasing in infection risk.
- Increase the risk of measles, diarrhea, and Anemia: deficiency of this increases the severity and risk of dying from infections like measles and diarrhea. Also, raise the risk of Anemia.
- Skin issues: low level of this vitamin create skin issues like hyperkeratosis and acne.
- Pregnant complications: The deficiency of this vitamin raises the risk of death in pregnant women and negatively impacts the fetus by slowing growth and development. Hence, during pregnancy always take care of your good level of this vitamin.
Recommended dosage
The recommended daily allowance (RDA) for vitamin A is 900 mcg and 700 mcg per day for men and women [1].
Toxicity
Chronic toxicity occurs when doses more than 10 times the RDA are ingested over a longer period.
The most common side effects of chronic toxicity of this:
- Vision disturbances
- Joint and bone pain
- Poor appetite
- Nausea and vomiting
- Sunlight sensitivity
- Hair loss
- Headache
- Dry skin
- Liver damage
- Jaundice
- Delayed growth
- Decreased appetite
- Confusion
- Itchy skin