Vitamin A and Beta-carotene

Vitamin A occurs only in animals. Plant foods contain beta-carotene, the vitamin A precursor, which, when eaten is converted to vitamin A. Beta carotene is a bright orange pigment, first isolated from carrots, hence its name. Beta-carotene is converted to vitamin A as it is needed. Any that is converted to vitamin A is used as a powerful antioxidant.

Roles of Vitamin A

Vitamin A works like a hormone, promoting protein synthesis and cell development, which is particularly important in maintaining the skin, the linings and coverings of organs, reproduction, growth and vision. It has two vital roles in the eyes: first keeping the cornea crystal clear and second promoting the transmission of the visual image from the retina to brain.

Vitamin A Deficiencies

They are common in the developing countries where malnutrition is more and give rise to specific problems, particularly in children. It is the commonest cause of blindness in children and the World Health Organisation has highlighted a specific problem with measles as Vitamin A deficiency children suffer more severely with this disease. Vitamin A deficiency is possible in the developed world too. Fast foods contain very little. Those on an exclusively junk food diet can expect eye problems starting with night blindness – not being able to see in the dark, and problems with bones, teeth, eyes and poor resistance to infections.

Vitamin A Toxicity

This is possible if supplements are used in excess. Beta-carotene does not have this problem because any surplus is simply stored in the skin and not converted to vitamin A. people who are supplementing their diet with massive quantities of carrot juice could have a problem, however, their skin could turn orange, but fortunately only temporarily.

The Sources of Vitamin A is animal produce.

The Source of Beta-carotene is plant foods.

This bright orange pigment is very widely distributed in plants and is especially rich in orange-coloured foods like carrots, cantaloupe melons, sweet potatoes, apricots and also in dark vegetables and fruits such as green, leafy vegetables and blue and black berries, where the orange colour is masked by the pigment.

The fat-soluble vitamins

These come with the fats and oils foods. As they are soluble in water, they need bile for absorption and they are transported in the body by proteins-carrying molecules. Any excess is stored in the liver or fat storage tissues, ready for future use. This means that a fresh supply is not needed as often as with the water soluble vitamins, but it does also mean that they are not so easy to get rid of. Toxicity is possible, so supplements should be used with care.