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Vitamin A is a fat-soluble vitamin and plays an important role in vision, development and maintenance of healthy skin, hair, mucous membranes; immune functions; and reproduction.

Vitamin A is also called retinol. It may be found in any of these forms:

' retinol - the animal form of vitamin A

' other retinoids - retinol, retinal, retinoic acid, and related compounds

' carotenoids - organic pigments that are naturally occurring in plants.

Daily requirement of Vitamin A '

Measurement of the amount of vitamin A is taken in retinol activity equivalents (RAE).

The recommended daily requirement for vitamin A is 700 RAE (retinol activity equivalent) per day for women and 900 RAE per day for men. The requirements are different for growing children, during puberty, and for women who are pregnant or lactating; therefore, please consult your doctor for differences.

Benefits of Vitamin A '

' Vitamin A promotes healthy surface linings of the eyes and the respiratory, urinary and intestinal tracts.

' Helps the skin and mucous membranes function as a barrier to bacteria and viruses.

What are the good sources of Vitamin A?

Eating a variety of foods that contain vitamin A (and carotenes) is the best way to get an adequate amount. Fit individuals who eat a balanced diet rarely need supplements. In fact, too much vitamin A can be toxic.

Alcohol, coffee, or excessive iron can all deplete the body's supply of this essential vitamin. But, the good news is that vitamin A is readily available from numerous food sources.
It can be obtained from food in two different forms '

1. Pre-formed vitamin A (called retinol or retinal), found in animal sources. Sources include liver, whole milk, and some fortified food products.

2. Pro-vitamin A (beta-carotene), from plant sources. Come from colourful fruits and vegetables.

The top ten vitamin A-rich foods:

' liver

' sweet potato

' carrots

' mango

' spinach

' cantaloupe

' dried apricots

' milk

' egg yolk

' mozzarella cheese

Low fat and skimmed milk is often fortified with vitamin A because it is removed from milk with the fat.
Vitamin A in foods that come from animals is well absorbed and used efficiently by the body. Vitamin A in foods that come from plants is not as well absorbed as animal sources of vitamin A.

A word of caution:

Too much vitamin A, either from animal sources or supplements, can prove toxic and is particularly dangerous during pregnancy. Excess beta carotene, on the other hand, isn't toxic but can give one a distinct orange hue.

What are the risks associated with vitamin A deficiency?

Zinc is required to make retinol binding protein (RBP) which transports vitamin A in the body. Therefore, a deficiency of zinc limits the body's ability to move vitamin A from the liver to body tissues.

' Night blindness is one of the first signs of vitamin A deficiency.

' Vitamin A deficiency diminishes the ability to fight infections, such as pneumonia.

' Deficiency may increase a child's risk of developing respiratory infections, diarrhea, decreased growth rate, slow bone development, and decrease likelihood of survival from serious illness.

Vegans who do not consume eggs and dairy foods need provitamin A carotenoids to meet their need for vitamin A. They should include a minimum of five servings of fruits and vegetables in their daily diet and regularly choose dark green leafy vegetables and orange and yellow fruits to fulfil recommended amounts of vitamin A.

Vitamin A storage '

Vitamins are easily destroyed and washed out during food preparation and storage.

' If you want to get the maximum vitamin possible from food, refrigerate fresh produce, and keep milk and grains away from strong light.

' Vitamin A can be lost from foods during preparation, cooking, or storage. To retain vitamin A:

' Serve fruits and vegetables raw whenever possible.

' Keep vegetables and fruits covered and refrigerated during storage.

' Steam vegetables , roast or bake meats instead of frying. Some vitamin A is lost in the fat during frying.

' If you take vitamin supplements, store them at room temperature in a dry place that is free of moisture.

What happens if Vitamin A is taken too much?

Some research suggests that having more than an average of 1.5mg per day of vitamin A over many years may affect bones and make them more likely to fracture when older.
Older people, particularly women, are already at risk of osteoporosis. This is where bone density reduces and so the risk of fractures increases.

If pregnant, having large amounts of vitamin A can harm your unborn baby. Therefore, if you are pregnant or thinking of having a baby, you should avoid eating liver or liver products because these are very high in vitamin A. You should also avoid taking supplements that contain vitamin A.