This essential human nutrient is an oil- soluble vitamin and is necessary for the growth and repair of the body’s tissues. It aids in the maintenance of the body’s immune system and helps combat infections. It has a vital role to play in maintaining healthy skin and is also known to protect the mucus membranes of the lungs, throat, mouth and nose.
Vitamin A is a term given to a large number of related compounds such as Retinol (an alcohol) and Retinal (an aldehyde) that are often referred to as preformed Vitamin A. Retinal can be converted to retinoic acid in the body, a form of Vitamin A known to affect gene transcription. These compounds in the body (retinal, retinol, retinoic acids and related compounds) are known as retinoids. Beta- carotene and other carotenoids can also be converted to retinol and are known as provitamin A. They can be acquired from various sources of the plant as well as animal kingdom.
Animal Sources: These are distributed between retinol and dehydroretinol.
Vegetable: The vegetable carotene sources can be split into alpha carotene, beta carotene, gamma carotene and crypto carotene.
In the presence of enough beta carotene, the body can manufacture Vitamin A on its own.
Benefits of Vitamin A:
It is required by the body for various purposes:
It defends against night blindness
Is essential for healthy skin
It boosts the immune system
It has antioxidant properties that are known to protect the body from harmful damage of free radicals such as pollution, smoke, ageing etc.
It reduces the risk of cancers and other diseases
It enhances the sense of taste and aids in the normal functioning of the digestive and urinary tracts. It protects the linings of the digestive tract, kidneys and bladder
Slows the process of ageing
It is required for the development and maintenance of the epithelial cells and plays a vital role in the formation of bones and teeth
It is required for the storage of fat and the synthesis of protein and glycogen
It is necessary for the formation of blood and helps the body secrete gastric juices essential for the process of protein digestion in the body.
It helps maintain good eye sight
It is essential for the growth and repair of the body tissues
Deficiency:
A deficiency of
Vitamin A can result in Night blindness and other problems of the eye related to dryness of the conjunctiva and cornea. It may even result in dryness of the skin, hair and poor or stunted growth.
If this nutrient is not taken in appropriate doses, it may result in dry, itchy eyes that tire easily. Major deficiency of the vitamin can result in permanent blindness due to ulcerated cornea.
Other problems include sinusitis, frequent colds, respiratory infections, abscesses forming in the ear, acne, boils and weight loss. Occurrence of insomnia, fatigue, reproductive problems, dryness of hair and scalp may indicate that not enough quantities of the vitamin are reaching the body.
Dosage:
The Recommended Daily Allowance (RDA) suggests an intake of 5000 IU per day for males and 4000 IU per day for females. 10, 000 IU is used in supplementation. Dosages exceeding 15,000 IU must be taken under medical supervision.
Side Effects:
These may include nausea, irritability, hair loss, bone and muscle pain, headache, liver damage, increase in lipid concentrations, skin changes, dryness, itchiness, menstrual problems, vomiting and headaches.
Food Sources:
Vitamin A can be obtained from various animal and plant sources. Animal sources include liver, beef, egg, milk, cheese, yogurt, margarine etc. Plant sources include carrots, sweet potatoes, carrot juice, vegetable soup, green leafy vegetables, broccoli, apricots, oatmeal, cereal, tomatoes, oranges, papaya, peaches etc.
Before taking any nutritional supplement, it is advisable to consult a registered medical practitioner. High doses of the nutrient are not recommended for children, pregnant and nursing women. The nutrients must be stored in a cool, dry place away from direct light. Retinol has the tendency to be destroyed by light and high temperatures. Vegetables rich in Beta- carotene must be soaked in water for long periods since the nutrients can be lost like that.
People on a low fat diet, alcohol or consuming high quantities of polyunsaturated fatty acids require higher than usual dose of Vitamin A. For best effects take Vitamin A with B group vitamins, C, D, E, choline, calcium, essential fatty acids, zinc and phosphorus.
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