Vitamin A is a fat soluble vitamin. The diet we consume contains two different types of Vitamin A. That which is found in animal products is preformed Vitamin A and the other found in plant foods is pro-vitamin A. Dietary supplements containing Vitamin A are also available usually in the form of retinyl acetate or retinyl palmitate.
- Retinoic acid- It is an important growth factor which is required to regulate genes
- Retinol- It is a form of Vitamin A which can be stored by the body and converted to retinal when ever needed
- Retinal: It is an important metabolite of Vitamin A which is essential for promoting good vision
- The corotenoid, beta-carotene is an antioxidant and protects the cells from damage caused by free radicals
The essential amount of Vitamin A which the body needs basically depends on the individual’s age and reproductive status. The amount of Vitamin A which an adult needs is:
- 0.7 mg a day for men is normally required
- 0.6 mg a day for women is normally required
- A daily diet provides all the Vitamin A which is required for an individual. Vitamin A is stored for future use if the body does not require it immediately, which means that Vitamin A need not be ingested every day.
There are two variants of Vitamin A, the first is found in meat, poultry and dairy products, whereas the second type pro-Vitamin A, is found in vegetables, fruits and other plant based products. The natural sources of Vitamin A are as follows:
- Beef liver and other organ meats
- Some types of fish, for eg: salmon
- Green leafy vegetables, orange and yellow vegetables like broccoli, carrots and squash
- Dairy products like cheese, eggs and yoghurt
- Breakfast cereals
- Vitamin A assists the eye’s light sensitive parts which enables us to see in the dim light or even during the night. But a deficiency in Vitamin A makes it difficult to see during the night. Our eyes may also become thick, lustreless or dry. Severe Vitamin A deficiency can result in total blindness.
- Vitamin A deficiency also affects our skin, which may become dry, scaly and rough. Broken nails and dry hair can result too.
The diseases which are caused due to lack of Vitamin A are:
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- Night Blindness: In the initial stages of Vitamin A deficiency, an individual is unable to see well in dim light; but in the advanced stages, an individual is unable to see objects in dim light or during the night
- Xerosis Conjunctiva: Due to Vitamin A deficiency, the conjunctiva gets dried, wrinkled and pigmented. Due to the pigmentation, the conjunctiva gets a smoky appearance.
- Xerosis Cornea: When the conjunctiva gets affected, then the dryness gradually spreads to the cornea, resulting in a hazy and lustreless appearance
- Keratomalacia: If xerosis of the cornea and conjunctiva are not treated, it may result in a condition known as Keratomalacia
- Follicullar Hyperkeratosis: Due to Vitamin A deficiency, the skin gets rough and dry
Keratomalacia