WONG ZI MIN D20131063419 GROUP A
Summary Writing
Vitamin A
Vitamin A is found only in yellow animal fats, in egg-yolk, milk and cheese. It is particularly plentiful in fish-liver oils, hence fish-liver oils are used for preventing and curing illness caused by lack of vitamin A. In a well-fed, healthy human being, the liver can store up sufficient vitamin A to meet the body's requirements for six months.
Although vitamin A itself is not present in plants, many plants produce a substance called carotene, formed from leaf-green which our bodies can convert into vitamin A. Carotene is the yellowish-red colouring matter in carrots. The greener a leaf is, the more carotene it usually contains. Hence the importance of green, leafy vegetables in the diet as a source of carotene. Tomatoes, papayas, mangoes and bananas contain more carotene than most other fruits. Red palm oil contains so much carotene that it is used instead of cod-liver oil. Thus, it is very valuable, both as a food-fat and for deep-frying.
Vitamin A and carotene are insoluble in water and they are not destroyed by heat unless oxygen is present. Boiling in water, therefore, does not destroy much vitamin A or carotene.
Vitamin A encourages healthy growth and physical fitness. Young animals soon stop growing and die if vitamin A is not present in their diet. This vitamin keeps the moist surfaces lining the digestive canal, the lungs and air passages healthy. It also helps keep the ducts of the various glands, the tissue that lines the eyelids and covers the front of the eyeball functional. As vitamin A helps these tissues build up resistance to infection, it is often called the anti-infective vitamin.
Some of the most common disorders in people are caused by a shortage of vitamin A, when the moist tissues become dry and rough. This often causes serious eye disease, followed by infection of the air-passages. The skin may also become flaky and rough. Another defect caused by shortage of vitamin A is 'night-blindness', when the affected person has distinct vision only in bright light.
As the body cannot produce vitamin A, it has to come from external sources. Thus a well-balanced diet is required and is usually sufficient to provide the necessary amount. There is therefore no need to supplement the need in the form of pills.

Summary Vitamin A is found only in certain food substances. It is also abundant in fish-liver oils. Our liver is able to store some vitamin A to meet our requirements. Carotene, is a substance which in our bodies can convert into vitamin A that can be found in green leafy vegetables, carrots and some fruits. Vitamin A is not easily destroyed by heat and insoluble in water. It is essential for healthy growth and physical fitness. It helps prevent the eyes infection. A lack of vitamin A could lead to eye diseases and skin disorders. The body will receive the necessary supply of vitamin when there is well-balanced diet. It is not necessary to take extra supplements.
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