Vitamin A (fat souble)

Question 1

Chemical name for Vitamin A?

Answer 1

Retinol

Question 2

What is retinol?

Answer 2

Retinol is a pale yellow solid which dissolves in fats and oils but not in water. It is found only in animal foods, but many fruits and vegetables contain carotenes, a group of orange pigments, which can be converted into retinol in the body. The most important of these pigments is beta carotene

Question 3

sources of retinol?

Answer 3

• liver and fish liver oils are good sources.
• fish liver oils are dietary supplements, not food sources. •Retinol is also found in butter, milk, cheese, eggs and oily fish. Vitamin A is also added to margarine.
• Liver, kidney and heart are good sources.

Question 4

Sources of beta carotene

Answer 4

Found in yellow, orange and green fruits and vegetables.
Richest source is carrots but is also found in mangoes, apricots and melons as well as oranges and red pepper.

Question 5

Functions of Vitamin A

Answer 5

1. Retinol is essential for growthand metabolism of all body cells
2. It is also required for he with and metabolism of all body cells, a complex substance formed from retinol and protein. Rhodopsin is a pigment found in the retina, a membrane at the back of the eye, and is necessary for vision in dim light
3. Vitamin A (beta -carotene) is also essential for the maintenance of healthy skin and surface tissues, particularly the moist mucous membranes such as the cornea at the front of the eye and the lining of the respiratory and digestive tracts
4. Beta - carotene is thought to act as an antioxidant in the body tissues removing free radicals. A high intake may give some protection against some forms of cancer.

Question 6

Defiency of vitamin A

Answer 6

1. Lack of vitamin A in the diet of children reduces growth
2. Without retinol the body is unable to synthesise rhodopsin, vision in dim light is impaired, causing a condition known as night blindness. If the deficiency is only slight the condition is easily reversed by increasing the intake of vitamin A. The popular saying that ‘eating carrots helps you to see in the dark’ contains an element of truth since carrots contain a significant amount of vitamin A. However, since the average British diet contains sufficient vitamin A, increasing the intake above the required level will cause no improvement in eyesight.
3. Vitamin A deficiency affects the health of the skire.g. roughened skin
4. Resistance to infection is lowered due to poor condition of the mucous lining of the respiratory tract.
5. In extreme cases the tear glands become blocked and the membranes at the front of the eye becoming dry and inflamed. This condition is known as xerophthalmia.
6. Severe and prolonged deficiency can lead to ulceration of the cornea causing blindness. Vitamin A deficiency is a common cause of blindness in developing countries where the diet is composed mainly of a staple cereal food and where fruits and vegs containing carotene are not available. It usually develops in children after weaning when vitamin A is no longer supplied by breast milk.

Question 7

Reccommended intake?

Answer 7

RNI reccommends for men is 700ug and women is 600ug
women need a extra 100ug per day during pregnancy and for her baby it is 950ug retinol per day.

Question 8

losses on cooking and storage?

Answer 8

• lost through slow drying fruit and veg
• retinol in fatty foods lost through oxidation (can be prevented by use of antioxidants, by refrigeration and by exclusion if light; use of foil)