Vitamins and minerals are an essential part of our diet. These are the micronutrients that play an initial role in various metabolic processes of our body. Vitamins are divided into fat-soluble and water-soluble categories that help us to differentiate among all the kinds of vitamins. Vitamin A is one of the main fat-soluble vitamins that are essential for the human body to promote health.
Vitamin A has diverse roles in human health. The compounds found in vitamin A are called retinoids- similar to that of retinol in terms of activity. Carotenoids are pigments and are present in food that we get through plants. Beta carotene’s absorption is less than retinoids. Our cells can convert retinol (the alcohol form of vitamin A) and retinal to active substances. Vitamin A’s every form serves different functions. After absorption, vitamin A reaches the liver for storage. Cells have special receptors to use vitamin A.
Forms of Vitamin A:
Retinol | The alcohol form |
Retinal | The aldehyde form |
Retinoic acid | The acid form |
Beta carotene | A precursor |
Benefits of Vitamin A in the Body:
- It promotes vision
- Supports reproduction
- Helps in growth
- Maintains healthy cell
Retinol is the storage form of the vitamin. Retinoic acid is responsible for embryonic development. Cell differentiation (immature to mature cell type) is also done by vitamin A. protein synthesis is also done by the vitamin. Vitamin A also helps protect the skin from sun damage. The integrity of the mucus membrane (having mucus-secreting cells) is maintained by vitamin A. Mucus protects the epithelial cells from damage. It is very interesting to know that in the retina (the innermost membrane), more than 100 million cells are present which contain 30 million vitamin A molecules. Rhodopsin is a light-sensitive pigment having retinal.
Beta Carotene- An Anti-oxidant:
Along with vitamin C, vitamin E, and selenium, vitamin A has a precursor that acts as an anti-oxidant. Not all beta carotene converts to active vitamin A. fruit and vegetables are rich in beta carotene. Vitamin A has a supportive role in infections. A large dose of vitamin A reduces the risk of certain infections. Vitamin A supplementation is recommended for measles. This supplementation reduces complications.
Deficiency of Vitamin A:
The deficiency of vitamin A causes many disorders. Some of them are as below:
Night-blindness
The deficiency of vitamin A is responsible for causing many problems like night blindness-slow recovery of vision (at the back of the eye). In dim light, rods are responsible for vision. Having vitamin (A) inadequacy, people remain blinded for many seconds in dim light.
Xeropthalmia
Xerophthalmia is also caused by vitamin A deficiency. It occurs in stages and is also called as the spectrum of ocular disease. The deficiency of vitamin A in the body hinders the essential functioning of the eye which leads to the development of ocular signs and symptoms. Severe Vitamin A deficiency (VAD) can affect the conjunctiva, cornea, and retina which all come under Xerophthalmia.
Keratinization
It is also caused by vitamin A deficiency. Keratin (water-insoluble protein) is hard and inflexible protein. Not having vitamin (A) leads to loss of goblet cells.
Xerosis
It is also caused by vitamin A deficiency in which abnormal dry skin is observed around the mouth and conjunctiva of the eye. Xerosis leads to the formation of abnormal dry, itchy, and scaly skin on the areas of arms and legs.
Toxicity of vitamin A
On the other hand, excessive intake of vitamin A leads to defects in bones. It suppresses bone-building activity. So, multivitamins should be taken with precautions. Abnormal cell death during pregnancy is also caused by excessive intake of vitamin A. Vitamin A is also not suitable for acne (chronic inflammation of follicles). Accutane is chemically different from vitamin A but this medication is prepared from vitamin A. Additive toxic effects can be reduced by taking precautions while taking supplements. The excessive intake of beta carotene leads to discoloration of the skin.
Vitamin A recommendation:
1 microgram of retinol counts as 1 RAE. Ten thousand international units are equal to three thousand micrograms of vitamin A. one international unit of retinol is equal to 0.3 micrograms of retinol. One international unit of dietary beta carotene is equal to 0.05 microgram RAE.
Foods Having Vitamin A and Color of Foods:
Carotene-rich sources should be a part of a balanced diet. Green, yellow, red, and orange colors are prominent in foods having beta carotene and vitamin A. dark green leafy vegetables have beta carotene masked by chlorophyll (green pigment of plants). So, colorful vegetables and fruit should be part of one’s plate. Vitamin A is found in deep orange vegetables. Some foods are rich in vitamin A and provide RDA in single servings.
Dietitian Zoya Faisal is a Gold medalist in Doctor of Nutrition and Sciences (UMT), and did her M.Phil in food and nutrition (UVAS), Pakistan. She can be reached at zoyazoya401@gmail.com
Disclaimer: The information in this article is not intended as sound medical advice for your particular illness; rather, it is meant to increase awareness of common health issues. Before implementing any recommendations made in this article or choosing a treatment plan based on its contents, you should always speak with a qualified healthcare professional.
