A Vitamins

All About A Vitamins

vitamin a

A Vitamins were the first vitamin to be discovered, so it was given the first letter of the alphabet for the name. A vitamins have a large number of uses in the body including keeping eyes healthy, bone growth, reproduction, aiding cell growth and also helping boost the immune system. Vitamin A helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses. However, vitamin A is not only absorbed directly but it is also created by the body by converting beta carotene into vitamin A.

A Vitamins can be found in various forms:

1. Retinol

Retinol one of the most usable (active) forms of vitamin A. It is found in foods that come from animals such as whole eggs, milk, meat, liver, and some fortified food products. Retinol can be made into retinal and retinoic acid (other active forms of vitamin A) in the body. The form of natural vitamins A absorbed when eating animal food sources, is a yellow, fat-soluble, vitamin with importance in vision and bone growth. Since the alcohol form is unstable, the vitamin is usually produced and administered in a form of retinyl acetate or palmitate.

Vitamin A that is found in colorful fruits and vegetables is called provitamin A carotenoid. They can be made into retinol in the body. Common provitamin A carotenoids found in foods that come from plants are beta-carotene, alpha-carotene, and beta-cryptoxanthin. Among these, beta-carotene is most efficiently made into retinol. Alpha-carotene and beta-cryptoxanthin are also converted to vitamin A, but only half as efficiently as beta-carotene. Beta carotene that the body can convert into vitamin A is found in many fruits and vegetables, especially the red, orange and green coloured ones.

2. Other retinoids: a class of chemical compounds that are related chemically to vitamin A, are used in medicine.

The Use of Health Vitamin A

Vitamin A is required for normal functioning of the immune system, so it is commonly known as the anti-infective vitamin. The skin and mucosal cells function as a barrier and form the body’s first line of defense against infection. Retinol and its metabolites are required to maintain the integrity and function of these cells. Vitamin A and retinoic acid (RA) play a central role in the development and differentiation of white blood cells, such as lymphocytes.

Vitamin A deficiency

Vitamin A deficiency can be considered a nutritionally acquired immunodeficiency disease . Deficiency vitamin A among children in developing nations is the leading preventable cause of blindness:

a. The earliest evidence of vitamin A deficiency is impaired dark adaptation or night blindness.

b. Mild vitamin A deficiency may result in changes in the conjunctiva (corner of the eye) called Bitot’s spots.

c. Severe or prolonged vitamin A deficiency causes a condition called xeropthalmia (dry eye), characterized by changes in the cells of the cornea (clear covering of the eye) that ultimately result in corneal ulcers, scarring, and blindness.

Vitamin A supplementation has been found to decrease both the severity and incidence of deaths related to diarrhea and measles in developing countries, where vitamin A deficiency is common .

Useful Info About A Vitamins

1. Consuming too much pure vitamin A can be toxic.

It is essential not to exceed the recommended daily allowance for vitamin A. The actual recommended allowance of vitamin A varies depending on a person’s age, sex and other factors. While the actual amount of vitamin A consumed may be toxic if the recommended daily allowance is exceeded, there is a far higher limit to how much beta carotene can be consumed.

2. It is advisable to concentrate on obtaining the greatest amount of beta carotene which the body can then convert to vitamin A, rather than consuming vast quantities of pure vitamin A rich foods.

3. Vitamin A that is produced from the high levels of beta carotene that are found in the vegetables. Eating lots of carrots helps you to see in the dark. Other foods which have high levels of beta carotene that can be converted to food vitamin A include tomatoes and dark green leafy vegetables, such as spinach.

4. Beta carotene is not only used to form vitamin A, but it is also a powerful antioxidant in itself. None of the beta carotene that is absorbed is wasted as any excess after conversion to vitamin A has taken place is used to fight the harmful free radicals within the body.

5. Vitamin A helps fight infections and illnesses by helping tissues that line various parts of the body, including the eyes, mouth, nose, throat and lungs, to grow and also to repair them if they are damaged to prevent infection.

6. Children need plenty of vitamin A to help their bones and teeth to develop properly.

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