Vitamin A is essential group of fat-soluble retinoid nutrients known as retinol, retinyl, retinal, and esters.
Vitamin A is the first vitamin discovered. This happened in 1920. After long research, it was proved that butter and egg yolk contains a substance necessary for the growth of animals. They also proved that the oil contains an active substance that does not break down under the influence of alkalis, and when they tried to mix it with soap, it remained outside the soap fraction. This substance was designated as “fat-soluble factor A” and later renamed vitamin A. Its other names are anti-infective vitamin, retinol, Dehydroretinol. There are 2 forms of vitamin A and these are Retinol (ready-made vitamin A) and Carotene (provitamin A, which is converted into vitamin A when it enters the human body). Carotene can be considered the plant form of vitamin A. It has a pale yellow color derived from beta-carotene – a pigment of plant origin. The good thing is that carotene has the same properties both in raw form and heat-treated, but when you try to store air for a long time, it is destroyed.
Dietary sources of vitamin A.
Plant products that are high in vitamin A are pumpkin, carrots, sweet peppers, spinach, broccoli, green onions, parsley, peaches, apricots, apples, grapes, watermelons, melons. Animal sources of vitamin A are liver (especially beef), fatty fish, butter, cream, whole milk, and eggs.
What is the required dose of vitamin A per day?
- Babies from 0 to 6 months: 400 μg
- Children from 7 to 12 months: 500 μg
- Bigger children from 1 to 3 years: 300 μg
- Kids – 4 to 8 years: 400 μg
- Boys from 9 to 13 years: 600 μg
- Girls from 9 to 13 years: 600 μg
- Men from 14 to 70 years: 900 μg
- Women 14 to 70 years: 700 μg
- Pregnant women: 750-770 μg
- Breastfeeding: 1200 -1300 μg
*1 microgram, (µg), = 0.000 001 g.
In some diseases, retinol is not enough and then the dosage can be increased by prescription. It is permissible to take 1/3 of the daily dose of retinol as a tablet supplement, and the remaining 2/3 the body should receive as food.
What are the beneficial properties of vitamin A?
Retinol is an antioxidant needed by the immune system. It takes care of eyesight and has an excellent effect on bones, skin, and hair. Vitamin A is part of the recovery process and the normal synthesis of proteins, promotes good metabolism, the activity of cell membranes, the formation of bones and teeth, and the growth of new cells. Vitamin A rejuvenates the body, fights viruses and bacteria, strengthens nails, and heals wounds. It has a good effect on the reproductive system of both sexes, increasing the production of sex hormones.
What are the harmful properties of vitamin A?
Vitamin A can only be harmful if excessively overdosed. Then the body is poisoned and acne, rashes, nausea and headaches appear. Sometimes the situation leads to inflammation of the cornea of the eyes and enlargement of the liver. It is necessary to take this vitamin seriously, especially on the part of pregnant women, because an overdose can harm the fetus and cause various pathologies.
How is vitamin A absorbed?
Vitamin A dissolves in fat and in order to be absorbed, fatty food is needed in the gastrointestinal tract. Some minerals are also needed. Vitamin A stores stay in the body long enough.
Vitamin A deficiency
With vitamin A deficiency, chicken blindness develops, skin rashes appear, premature aging of the skin begins, susceptibility to various diseases increases, the severity of maturation decreases, dry eyes, conjunctivitis, dandruff, hair loss and loss of appetite appear.
Excess vitamin A.
Vitamin A overdose leads to vomiting, headache, flushing, drowsiness, leg bone pain, menstrual irregularities.
Why is vitamin A important for the eyes?
Plant sources of vitamin A are the main protection of the eyes against cataracts and reduce the risk of degeneration and blindness.
The most important antioxidant
Vitamin A promotes the body’s interaction with free radicals, including oxygen free radicals. For this reason, it is an effective antioxidant. Its antioxidant action plays an important role in diseases of the heart and arteries, protects patients with angina and increases the level of good cholesterol. Retinol is one of the means for the prevention of cancer and the appearance of new tumors after surgery. Given its role in the immune system, vitamin A is also very important for carriers of the HIV virus because it protects against additional infections.
Interaction of vitamin A with other substances
Retinol significantly enhances the antioxidant properties of vitamin E, but can be completely destroyed if the body does not have the necessary amount of vitamin E. Retinol does not stay long in the body if it suffers from a deficiency of vitamin B4. Vitamin E protects Retinol from oxidation in both the gut and tissues. Therefore, vitamin E deficiency will lead to vitamin A deficiency. Therefore, both should be taken together. Zinc is needed to convert vitamin A to the active form. If the body lacks zinc, the molecule that carries vitamin A through the intestinal wall to the blood and from there to all tissues cannot be synthesized. The two components are interdependent, as vitamin A also plays a role in zinc absorption.
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