This is an automatically translated article.
Vitamin A (also known as retinol) is an essential substance for humans belonging to the group of fat-soluble vitamins. In some foods of animal origin, the main form of vitamin A is retinol, but can also exist as retinal or as retinoic acid.Continuous deficiency of vitamin A produces a series of changes, the most destructive to the eye. These changes in vision are collectively known as dry eye disease. The first is the drying of the conjunctiva as the epithelium of the tear and mucus glands is replaced by a keratinized epithelium. This is followed by the accumulation of keratin debris into small translucent patches, finally by erosion of the rough stratum corneum surface with degeneration, destruction of the cornea and total blindness.
Therefore, vitamin A is indicated for the treatment of diseases such as dry eyes, night blindness, slow growth in children, susceptible to respiratory infections, acne, brittle dry skin and nails, quick healing of wounds. , burn.
Because vitamin A is fat-soluble, it is more difficult to remove excess absorbed from food than water-soluble vitamins. Therefore, overdose can lead to vitamin A toxicity.
It can cause nausea, jaundice, allergies, anorexia, vomiting, blurred vision, headache, muscle damage, lethargy and change in behavior love. Acute poisoning generally occurs at doses of 25,000 IU/kg and chronic poisoning occurs at 4,000 IU/kg daily for a period of 6-15 months.
However, liver toxicity can occur at levels as low as 15,000 IU/day, with an average toxic dose of 120,000 IU/day.
In people with impaired renal function 4,000 IU/kg per day can also cause significant damage. Heavy drinking can also increase vitamin A toxicity.
Khô mắt do thiếu vitamin A
The above symptoms of poisoning only occur when taking drugs with vitamin A to drink. Other forms of caretonoids (such as beta carotene in carrots) do not cause such symptoms. Therefore, it is safer to supplement vitamin A through food.
A recent study showing a correlation between low bone mineral density and high vitamin A intake also warned that an overdose of this vitamin can cause bone diseases.
Note that vitamin A doses are usually expressed in international units (IU) or retinol equivalents (RE), with 1 IU = 0.3 micrograms of retinol. The absorption of provitamin A is also highly dependent on the amount of lipids digested with food. Therefore, users of this drug need to strictly follow the dosage instructions and pay attention to a greasy diet while taking the drug.
