Vitamin A was discovered in 1913. It is fat-soluble vitamin. Vitamin A is also known as retinol or carotenoids. Vitamin A is an “anti-infective” vitamin because of its functions of supporting the immune system. It exists in several forms and not as a single compound.
What are the functions of the vitamin A?
Vitamin A aids formation and maintainance of healthy teeth, skin, skeletal and smooth muscles and mucous membranes. It produces the pigments in the eye’s retina and thus it is termed as retinol. It promotes good vision, particularly in low light. Vitamin A is also necessary for reproduction and breast feeding. It is also required for the proper functioning of our immune system.
What are the food sources of vitamin A?
Retinol or preformed vitamin A is found in sources of animal origin while carotenoid or provitamin A is found in fruits and vegetables. Our body can transform some members of the carotenoid family like alpha-carotene, beta-carotene and gamma-carotene into vitamin A. These carotenoids are sometimes referred as “provitamin A” and retinol as “preformed vitamin A.”
Animal sources of vitamin A are liver, milk, cream, cheese, eggs, meat, kidney and cod fish oil. Though these resources are rich in vitamin A, except skimmed milk the other sources are high in cholestrol and saturated fats.
Retinol, which is an active kind of vitamin A, is found in whole milk, animal liver and certain fortified foods.
Sources of beta-carotene are carrots, sweet potatoes pumpkin, winter squashes, pink grapefruit, cantaloupe apricots, spinach, broccoli and almost all dark green, leafy vegetables. The beta carotene content increases with respect to the intensity of the color of a vegetable or a fruit. All these vegetable sources are free from cholesterol and fat.
What are the symptoms of vitamin A deficiency?
Acne problems and impaired vision are the earliest symptoms of vitamin A deficiency. Vitamin A deficiency causes night blindness (impaired vision in reduced light). Persistent deficiency can be serious and it mostly affects the eye. The ocular changes are collectively termed as xerophthalmia. It starts with the dryness of the conjunctiva known as xerosis. This is then followed by bitot’s spots, keratomalacia and finally total blindness. Vitamin A deficiency may lead to impaired immunity, hypokeratosis etc.
What does happen when you take vitamin A in large amounts?
Heavy doses of vitamin A can result in birth defects. If an adult takes in several hundred thousand IU of vitamin A, then acute vitamin A poisoning will occur. An adult who takes in over 25000IU of vitamin A regularly every day may experience symptoms of chronic vitamin A poisoning. Infants and children are sensitive to even smaller dosage of vitamin A.
Large amounts of beta-carotene can change the skin color to orange or yellow. Once the intake of beta-carotene is decreased, the condition of the skin will return to normal.
What are the daily dosage recommendations of vitamin A?
To meet the daily requirements of necessary vitamins you have to eat a well balanced diet. The recommended daily intake of vitamin A is
For Infants
• Upto 6 months - 400 mcg
• 7 to 12 months - 500 mcg
For Children
• 1 to 3 years - 300 mcg
• 4 to 8 years - 400 mcg
• 9 to13 years - 600 mcg
For Adolescents and Adults
Males:
• Age 14 and above - 900 mcg.
Females:
• Age 14 and above - 700 mcg
Pregnant women or those who are producing breast milk will require higher amounts of the vitamin. So you should consult your doctor for the correct dosage.
Thus, vitamin A is a very essential vitamin for normal functioning of our body and you should take in the right quantities of vitamin A for leading a healthy life.
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