How does vitamin A help the eyes?

Vitamin A is a fat-soluble vitamin, it has the effect of enhancing immunity, increasing the body's resistance to fight infections, and it is also involved in the function of cell growth and differentiation. cell.
In particular, vitamin A plays a very important role in the eyes, it has a role in preventing night blindness caused by dry eyes, thereby avoiding leading to dry conjunctiva, corneal ulcers - these are the possible causes of blindness. .
Vitamin A is directly involved in chemical reactions in the rods and cones in the retina of the eye. Vitamin A also creates retinal pigment, helps regulate the eyes and supports the eyes to see in low light conditions. At the same time, vitamin A is also one of the components that make up the tear film (tear film) and helps this film adhere to the corneal surface.
Many studies on ocular surface pathology have shown a close relationship between tears and ocular surface. Our tears are made up of three fluids: oil, water, and mucus (mucin).
The current state of environmental pollution, air, sunlight, combined with the use of computers, phones or stress all cause a decrease in tear production. This leads to an imbalance in the surface of the eyeball, causing damage to the cornea. From there, it causes symptoms such as dry eyes, eyestrain, blurred vision, foreign body sensation in the eyes, eye pain, photophobia, itching, discomfort in the eyes, tearing and congestion, eye discharge.
A study in Japan, performed on eye patients, showed that vitamin A helps the eyes synthesize and stabilize the mucin that helps tears adhere to the corneal surface. At the same time, vitamin A also supports the synthesis of mucus in the eyes and promotes epithelial healing.
These two mechanisms play an important role in restoring corneal epithelial cells and repairing damage to the mucin layer, thereby helping to improve dry eyes and correct vision. After the experiment ended, the volunteers improved more than 10 symptoms related to dry eyes.
This study also showed no serious adverse events or adverse reactions of vitamin A to the eyes. Scientists hope this study will help increase the effectiveness of the treatment of eye diseases, especially due to vitamin A deficiency. Some other studies have shown that taking vitamin A supplements that increase blood levels of vitamin A precursors higher than normal can reduce the risk of macular degeneration by up to 25%. Therefore, adequate vitamin A supplementation will help you fight some eye diseases such as macular degeneration and age-related eye problems.

Vitamin A is also an antioxidant that helps protect the eyes, promoting the health of the mucous membranes and corneas of the eyes. It also helps fight infections caused by bacteria or viruses. In addition, vitamin A also plays an important role in supporting the structure of lacrimal epithelial cells, protecting cell membranes against hypoxia and free radical damage.
Therefore, a lack of vitamin A will cause serious health effects, especially the health of the eyes. Vitamin A deficiency can cause a number of conditions such as:
When vitamin A deficiency, you will have many eye-related diseases such as:
Night blindness Hyperplasia of squamous cells causes surface keratinization. Damage or destabilization of the tear film causes dry eyes. Long-term dry eyes can cause conjunctivitis and keratitis. Long-term keratitis will cause corneal scarring complications that can cause temporary blurred vision or permanent blindness if not treated promptly. Reducing the body's resistance to disease should increase the mortality rate in children.
Slowing down children's growth, if vitamin A deficiency occurs early, it can affect the intellectual development of children when they reach school age.
Common signs of vitamin A deficiency in eyes include:
Severely impaired vision in low light conditions. There is a feeling of dryness and burning in the eyes. Eye pain can range in severity from mild to severe. Red eyes Upper and lower eyelids stick together. Temporary or permanent blurred vision Fear of exposure to bright light Or orbital pain Or tear secretion due to irritation of the lacrimal glands.

Excess vitamin A also causes poisoning, so this vitamin cannot be used arbitrarily. Vitamin A is fat-soluble and can be accumulated in the body.
If supplementing with a large amount of vitamin A daily, it will lead to symptoms such as:
Liver toxicity Joint pain Headache Bone changes Vomiting Dry, flaky skin Causes bulging fontanelles in children However, fortunately, These symptoms are rare because the addition of vitamin A and beta carotene (provitamin A) from the diet usually does not exceed the body's needs. Unless you use too much beta carotene for a long time will lead to beta carotene metabolism disorders in the body and the skin becomes yellow, this phenomenon is called Xantoza. However, this phenomenon will disappear when you stop using foods rich in this substance.
Oversupply of vitamin A in pregnant women can cause birth defects. Therefore, the World Health Organization (WHO) recommends that pregnant women should not use vitamin A in excess of 3,000 mcg/day (equivalent to 10,000 IU) or should not exceed 7,500 mcg/week (25,000 IU) ).
A single dose of about 150,000mcg (500,000IU) of vitamin A can be toxic to pregnant women. Therefore, pregnant women must use the correct dose of vitamin A.

Birth defects commonly encountered by mothers due to excessive use of vitamin A include:
Face and head deformities such as: cleft lip - cleft palate,...4 Cardiovascular disease Genital malformation Disease CNS Deformities in skeletal and muscular systems. Vitamin A should be supplemented with the diet, because vitamins in the diet are better because they cause less side effects.

Cases that need vitamin A supplementation include:
- Vitamin A deficiency: this is a fairly common condition, the treatment as well as the way to prevent this condition is very simple, that's just taking vitamin supplements. A. Vitamin A deficiency can occur in malnourished people, people with diabetes, cystic fibrosis,...
– Children with vitamin A deficiency are suffering from measles: give children a supplement. Vitamin A seems to help reduce the risk of death or complications from measles.
– Oral leukoplakia: Studies have shown that taking vitamin A supplements can help treat oral leukoplakia.
– Postpartum diarrhea: vitamin A supplementation during pregnancy and postpartum in malnourished pregnant women helps to limit the occurrence of postpartum diarrhea.
– Reduce maternal mortality: Undernourished pregnant women, if taking vitamin A supplements before and during pregnancy, can reduce the mortality rate by 40%.
– Prevention of night blindness in pregnancy: for undernourished pregnant women, taking vitamin A supplements will reduce the incidence of night blindness by 37%, and it will be even more effective if vitamin A supplements are taken together with the cause. zinc trace element.
– Eye disease affecting the retina: Taking vitamin A supplements may slow the progression of eye diseases that damage the retina.
– Cervical cancer: Recent studies have shown that high doses of vitamin A supplements have the ability to reduce the risk of cervical cancer. However, this benefit was only achieved when women supplemented with both forms of vitamin A, retinol and carotenoids, if retinol alone would not have any effect.

The amount of vitamin A needed per day for each person depends on age and sex, here are the recommendations of the US National Institutes of Health (NIH):
Men: From 1 to 12 months old: 400mcg - 500mcg 1 - 13 years old: 300mcg - 600mcg 14 years old and up: about 900mcg Female: 1 - 12 months old: 400mcg - 500mcg 1 - 13 years old: 300mcg - 600 mcg 14 years old and up: about 700 mcg

The US National Institutes of Health (NIH) also recommends separate levels of vitamin A for pregnant and breastfeeding women.
Pregnant women 14 - 18 years old: about 750mcg 19 - 50 years old: about 770 mcg Lactating women 14 - 18 years old: about 1,200mcg; 19 - 50 years old: about 1,300mcg. The amounts mentioned above are calculated for people who are healthy and have a well-rounded diet. Your doctor will probably give you a separate dose, suitable for your health condition, so you need to follow your doctor's instructions.

To prevent vitamin A deficiency, you need to do the following well:
Make sure your diet is full of nutrients, especially foods rich in vitamin A such as eggs, milk, liver, fish oil, ripe mango, papaya, gac, sweet potato, carrot and dark green vegetables. Women during pregnancy and lactation need to eat enough nutrients, pay attention to foods rich in vitamin A, rich in carotene, high in protein and fat. Pay attention to immunization for children, especially measles vaccine. When preparing food for children, it is necessary to have adequate nutrients and vitamin A. It is recommended to use many different foods to enrich and diversify meals. increased absorption in children. Prioritize the use of foods rich in vitamin A and carotene, and at the same time, the meal should also have enough protein and fat to help increase absorption and metabolism of vitamin A. Vitamin A is one of the important micronutrients, needed essential for healthy eyes. Therefore, when there are signs of vitamin A deficiency, you need to supplement promptly. In addition to adequate vitamin A supplements, you need to remember to take care of your eyes regularly. At the same time, you should go for an eye exam once a year to check your eyes, detect and promptly treat eye diseases.