From the Vitamin Diary

Vitamin A (Retinol) Information - For Better Eyesight

Approximately 80% of vitamin A is absorbed in the human system. It is passed along with fat through the lymphatic system into the bloodstream. The absorption of vitamin A increases if it is taken with fats.Absorption is more rapid in men than in women. The absorption of this vitamin is poor in cases of diarrhea, jaundice, and abdominal disorders. Vitamin A is stored in the liver. A healthy person can store about 97.2 mcg of vitamin A per g of liver. Thus an average liver weighing 1500 g can store 150,000 mcg of vitamin A.
Approximately 20% of vitamin A which is not absorbed is excreted within one or two days into the faeces. Of the 80% absorbed, about 20% to 50% either combines with or burns down into products that are excreted within about one week in the faeces or urine. The remainder 30% to 60% of the absorbed vitamin A is stored.

Recommended Daily Allowance - Vitamin A
Men	600 mcg
Women	600 mcg
Children	600 mcg
Infants	350 mcg
Lactating Women	950 mcg

Benefits of Vitamin A - Functions in the body
1. The best-defined function of vitamin A is its role in vision. It provides the required stimulation for vision in the retina.
2. In addition, vitamin A is required for growth, reproduction, and the maintenance of life. It builds up resistance to respiratory and other infections, and keeps the mucous linings and membranes of the body, especially those of the eyes, lungs, stomach, and intestines, in a healthy condition.
3. It prevents eye diseases, aids in the secretion of gastric juices, and the digestion of protein.
4. It also plays a vital role in preventing and clearing up infections of the skin, and in promoting healthy hair, teeth, and gums.
5. Vitamin A increases the permeability of blood capillaries, thereby contributing better tissue oxygenation.
6. It also helps prevent premature ageing and senility, increases life expectancy, and extends youthfulness .

Vitamin A - Deficiency Symptoms
Prolonged deficiency of vitamin A may result in inflammation of the eyes, poor vision, and night blindness . There is an increased susceptibility to infections , especially of the respiratory tract, in the form of frequent and prolonged common colds . Vitamin A deficiency may lead to lack of appetite and vigour, defective teeth and gums, skin disorders such as acne, boils and premature wrinkles . When vitamin A is present in insufficient amounts, the mucous membranes of the nose, throat and mouth, the bronchial tubes, lungs, intestinal tract, kidneys and vagina are greatly affected. Eventually the mucous membranes of the entire body lose their ability to secrete the normal quantities of mucus needed to protect them from irritation, and the body degenerates rapidly . Other deficiency symptoms include retarded growth in children, dry and dull hair, dandruff, excessive hair loss, ridged nails, and a poor sense of taste and smell.

Sources of Vitamin A
Foods rich in vitamin A (retinol) include those of animal origin such as sheep liver, egg yolk, whole milk, butter and ghee (clarified butter). Vegetables such as colocasia, turnip greens, drumsticks, beet, carrots, and spinach contain a lot of carotene. Fruits like mangoes, apricots, gooseberries, raspberries, and oranges are also rich in carotene.

Rich Food Sources of Vitamin A - values per 100g
Vegetables (Carotenoids)	mcg	Fruits (Carotenoids)	mcg
Carrots	12000	Mangoes, ripe	2800
Parsley	7000	Persimmon	2200
Spinach	5600	Apricots, fresh	2200
Sweet Potatoes	4000	Oranges	1200
Broccoli	2000	Raspberries	200
Meat, Poultry, Milk products & Fats(Retinol)			mcg
Cooked calf's liver			40000
Liver sausage			2500
Butter			850
Cow's Milk			420

More than a hundred different cartenoids have been identified and these have individual amounts of vitamin A activity. Between 6 and 12 mcg are equivalent to 1 mcg of retinol.
The dose of retinol in vitamin supplements is often given in International Units (IUs). To convert mcg into IUs, multiply by 3.33. For example, 100g of mangoes contain 2800 X 3.33 = 9324 IU.