FoOdS ThAt GiVe ViTaMiN A

Vitamins have been one of the major nutritional discoveries of the 20th century. Health foods and cosmetics started promoting the vitamins. Vitamins cannot synthesise in the body in adequate amounts and therefore it should be supplied in food.

Deficiency of vitamins leads to various illnesses. Few of the vitamins are soluble in water where as some are soluble only in fat.

Vitamin A is a fat-soluble vitamin. MC Collum and Davis discovered this vitamin in 1913 at John Hopkins University in America, when they isolated a growth factor in egg yolk, butter, and cod liver oil. In 1920 Rosenhein and Drummond demonstrated the relationship of vitamin A to the plant pigment carotene. Carotene is a precursor of vitamin A in the body and is therefore known as pro-vitamin A.

Carotene is present in green and yellow vegetables and yellow fruits. Animals do not produce this. Carotene has alpha, beta, and gamma isomers. Among these isomers beta-carotene is the most widely distributed in food and more effectively converted into vitamin A. It does not get destroyed at ordinary levels of heat.

Vitamin A plays an important role in various functions of the body. It plays an important role in maintaining proper vision. This vitamin is required for formation and integrity of the epithelial tissue result in a healthy glowing and soft skin. It is required for proper growth and development of skeletal system of the body. Role of this vitamin in the immunological defence mechanism of the body is very important. Beta-carotene also has an important role as an anti-oxidant. Studies have shown that diets high in carotenoids are often associated with a reduced risk of certain cancers. This protection is however seen only if the source of beta-carotene is a food, and not the supplements.

Vitamin A is absorbed along with fat from the proximal small intestine. The absorption is more rapid in men than women and the absorption is decreased with intestinal roundworm, hookworm, and giardiasis infestations. After absorption this fat-soluble vitamin is stored in the liver. Among the carotene that is absorbed from vegetable foods, beta-carotene accounts for about 33-50%. Only one third of the beta-carotene is absorbed and only one half of what is absorbed is converted to vitamin A. Liver can store large amounts up to about 100000mg of vitamin A these reserves may last for 6-9 months.

Vitamin A is present in animal foods like whole milk, curd, butter, ghee, egg yolk, and liver. The liver oils of certain fish like cod halibut and shark are the richest sources of vitamin A. Spinach, amaranth, coriander leaves, curry leaves, drumstick leaves, ripe mangoes, papaya, fresh apricot, orange, raspberry, carrot, yellow pumpkins, mint, lettuce and tomato are rich in carotene. Among pulses red gram and masoor dhal has most carotene content.

Source

Carotene contentug /100g
Vitamin A equivalent(ug) Per 100g
Red palm oil
25,000-33,000
4167-5500
Green leafy vegetables
Amaranth leaves
1,600-7,000
266-1166
Cabbage
1300
217
Coriander leaves
7,000-8,000
1166-1333
Curry leaves
8,000
1333
Drumstick leaves
7700
1283
Fenugreek leaves
2700
450
Radish leaves
4500
750
Mint
1800
300
Spinach
3600
600
Other vegetables
Carrot
1,300-2,600
217-434
Pumpkin, yellow.
600-720
100-120
Fruits
Jack fruit
320
54
Mango, ripe
3000
500
orange
210
35
Tomato ripe
190
32*Source -Food & Nutrition Dr.M.Swaminathan

Night blindness
Bitot's spot
Xerophthalmia
Xerosis conjunctiva
Xeroasis cornea
Keratomalacia
Follicular hyper keratosis or phrynoderma

Consumption of excess of vitamin A causes headache, fatigue, irritability, nausea, vomiting, and anorexia, which will disappear on withdrawal of vitamin A in take.

Vitamin A and carotene are stable to ordinary cooking methods, though some loss may occur at temperature above 100 degree Celsius as when butter or palm oil is used for frying.

Fruits and other foods that are dried in the sun lose much of their vitamin A. Considerable losses of vitamin A may occur in fish liver oils bottled in colourless glass.