Does taking vitamin A have side effects?

The article was professionally consulted with resident Doctor Duong Van Sy - Doctor of Pediatrics - Neonatology - Department of Pediatrics - Neonatology - Vinmec Hai Phong International General Hospital.

Vitamin A is a fat-soluble nutrient. Your body converts beta-carotene into vitamin A. People who eat poorly or have a high need for vitamin A, such as patients with measles or pancreatic disease... can supplement by taking it orally. vitamin A. However, taking vitamin A supplements can cause some unwanted effects.

Although vitamin A is often thought of as a single nutrient, vitamin A is in fact the name for a group of fat-soluble compounds, including retinol, retinal, and retinyl esters. There are two forms of vitamin A found in foods.
Converted vitamin A - retinol and retinyl ester - occurs only in animal products, such as milk, liver and fish. Meanwhile, the second form is a precursor to vitamin A - carotenoids that are abundant in plant foods such as fruits, vegetables, and oils. To use them, the body must convert both forms of vitamin A to retinal and retinoic acid, the active forms of the vitamin.
Because vitamin A is fat-soluble, it is stored in body tissues for later use.
Most vitamin A in the body is stored in the liver as retinyl esters. These esters are then broken down to all-trans-retinol, which binds to a retinol-binding protein (RBP). It then enters the bloodstream, at which point your body can use vitamin A.

Vitamin A is essential for your health, supporting cell growth, immune function, development and fetal vision.
One of the most important functions of vitamin A is its role in vision and eye health. Retinal, the active form of vitamin A, combines with the protein opsin to form rhodopsin, a molecule required for color vision and low light vision. Vitamin A also helps protect and maintain the cornea - the outermost layer of the eye - and the conjunctiva - a thin membrane that covers the surface of the eye and the inside of the eyelid. In addition, vitamin A helps maintain surface tissues such as the skin, intestines, lungs, bladder and inner ear.
Vitamin A supports immune function by supporting the development and distribution of T cells, a type of white blood cell that protects your body from infection. What's more, vitamin A supports healthy skin cells, reproduction, and fetal development. Vitamin A is necessary for eye health, vision enhancement, immune function, cell growth, reproductive support and fetal development.

Although vitamin A deficiency is rare in developed countries, it is common in developing countries, including Vietnam.
Vitamin A deficiency can lead to serious health complications. According to WHO, vitamin A deficiency is the leading cause of preventable blindness in children worldwide.
Vitamin A deficiency also increases the severity and risk of death from infections such as measles and diarrhea. In addition, vitamin A deficiency increases the risk of anemia and death in pregnant women, and negatively affects the fetus by slowing growth and development. Less severe symptoms of vitamin A deficiency include skin problems such as hyperkeratosis and acne. Certain groups such as premature infants, people with cystic fibrosis and pregnant or breastfeeding women in developing countries are at increased risk for vitamin A deficiency.
Vitamin A deficiency can lead to blindness, increasing the risk infections, pregnancy complications, and skin problems.

A healthy and varied diet will provide all the vitamin A needs that the body needs. Too much vitamin A can be harmful, and too much vitamin A during pregnancy has been linked to birth defects.
Just as a lack of vitamin A can have negative health effects, getting too much vitamin A can also put you at risk.
The amount of vitamin A needed to supplement each day for men and women is 900 mcg and 700 mcg, respectively. This level can be easily achieved by following a proper diet. However, it's important that you don't take your vitamin A supplements above the tolerable limit (UL) of 10,000 IU (ie 3,000 mcg) for adults to prevent toxicity.
Taking too much vitamin A can lead to serious and possibly even fatal side effects if taken in extremely high doses.

Acute vitamin A toxicity occurs over a short period of time when an excessively high dose of vitamin A is consumed, while chronic toxicity occurs when doses greater than 10 times the RDA are taken over a longer period of time.
Although rare, taking too much vitamin can cause chronic toxicity, acute vitamin A toxicity with more serious symptoms, including liver damage, increased cranial pressure, and even death. . Acute toxicity occurs with a single dose of 350,000 units for neonates and more than 2 million units for adults.
Chronic toxicity occurs in infants (3 to 6 months) at 8,500 Units per day for 1 to 3 months and in adults at 1 million units per day for 3 days, at 500,000 units per day for 2 months or 50,000 units per day for more than 18 months.
Taking more than 10,000 mcg of vitamin A daily with vitamin A supplements can cause:
Thin bones Liver damage Headaches Diarrhea Nausea Skin irritation Joint and bone pain Birth defects.

In addition, vitamin A also causes a number of undesirable effects, including:
Bleeding from the gums or mouth pain Unusually confusion or excitement Rapidity or drowsiness Double vision Severe discomfort Peeling skin, especially lips and palms If you experience any of the following side effects, you should immediately seek medical attention for timely treatment:
Bone or joint pain Convulsions Dry or cracked skin Dry mouth

Fever Fatigue Body Headache Increased skin sensitivity to sunlight Increased frequency of urination, especially at night or urine output Irritability Loss of appetite Hair loss Abdominal pain Unusual fatigue Vomiting Yellow skin

Vitamin A deficiency and excess can both cause serious side effects, so it's important to meet the RDA of 700 - 900 mcg per day for adults, not exceeding the daily limit of 3,000 mc g.
A healthy and balanced diet is the best way to provide your body with a dose of this essential nutrient.

Reference source: Webmd.com; Mayoclinic.org; Healthline.com