Vitamin A



Many of us understand that “Vitamin A” refers to a single nutrient required by human body. You will be surprised to know that vitamin A is a group of different nutrients. Each nutrient present in Vitamin A group has different function to perform for our body. The two most important forms of Vitamin A are Retinoids & Carotenoids. Retinoids are obtained from animal foods, and also known as preformed Vitamin A. Carotenoids, are obtained from plant foods, and known as pro-vitamin A. Our body can convert the carotenoids into retinoid forms under some conditions. Both forms of vitamin A are needed by our body for healthy functioning of different body systems.

Retinoids
Retinoids are a form of Vitamin A which are obtained from animal foods. Retinoids are required by our body for specific functions which are not performed by carotenoids. As the two main forms of vitamin A differ from each other in their functions, therefore, both forms are essential for our body. Retinoid forms of vitamin A are required during pregnancy, infancy, child growth, vision, synthesis of red blood cells and increasing resistance against infectious diseases.

Carotenoids
As retinoids are required for our body to perform specific functions, similarly carotenoids perform specific functions for maintaining optimum health. The most important function of carotenoid forms of vitamin A is to protect our body against recurrent inflammation. It also acts as an anti-oxidant. The most important carotenoids required by our body maintain proper vision. The two main carotenoids found in the retina of our eye are zeaxanthin and lutein. So, if you are looking forward to prevent old age diseases such as cataract, macular degeneration or any other disease related to vision, then you have to choose a diet rich in the above mentioned two carotenoids.
Some individuals have an ability to convert the carotenoid form of vitamin A into the retinoid form thereby, helping to prevent diseases related to deficiency of retinoids. The three main forms of carotenoids that can be effectively converted to retinoid forms under some conditions are beta carotene, alpha carotene and beta-cryptoxanthin. Some individuals do not have the capacity to do this conversion due to certain factors that inhibit the conversion. The factors that do not allow this conversion include excessive alcohol intake, continuous intake of some over the counter medications, digestive problems, bacterial imbalances in the digestive system, and imbalance of vitamin A and D. So, if you are vegetarian and do not take animal foods then you may be eating more carotenoids and your body may not have capacity to convert carotenoids to the retinoid form due to any of the above factors, which may cause a problem. Beta-carotene is the best carotenoid that can be converted to the retinoid form by our body.

Benefits of Vitamin A

Health benefits of Retinoid forms of vitamin A
Retinoid form of vitamin A support normal vision. Other functions performed by vitamin A in human body include optimum functioning of the immune system, helps in growth, and development of bones, formation of red blood cells, helps in proper reproductive functions in males and formation of healthy tissues.

Healthy vision
There are different pigments present in the retina of our eye that store vitamin A. There are two types of cells present in our retina. One is rod cells and other is cone cells. Rod cells contain a pigment called rhodopsin and cone cells contain other pigment called iodopsin. Rhodopsin is required for night vision and iodopsin is needed for day vision. Thus, vitamin A is required for normal functioning of these two pigments of our eye.

Boosts immune system
Vitamin A plays an important role in boosting our immune system and preventing inflammatory conditions of our digestive system. We eat different kinds of food everyday and sometimes we consume harmful substances which are foreign to our body. We need a strong immune system to recognize these foreign substances so that we remain free from inflammation of the digestive tract. Research has been done and it is found that vitamin A plays an important role to support the normal functioning of T lymphocytes and B lymphocytes which are protective in function.

Helps in reproductive functions
Research has shown that vitamin A plays an important role in the production of healthy sperms in men. It is also an important nutrient required for bone development and mineral absorption.

Carotenoid forms
Carotenoids are said to be most important nutrients that has anti-inflammatory, anti-cancer and anti-aging properties. Researchers believe that vitamin A helps in the prevention of growth of cancerous cells by enhancing the communication between the cells. It is found that vitamin A increases the communication between the cells of body and prevents spread of cancerous cells.

Food sources of Vitamin A
You can get retinoid forms of vitamin A from animal foods such as milk, cheese, yoghurt, eggs, tuna, chicken, cod and salmon.
Carotenoid forms can be obtained from fruits and vegetable foods such as carrots, green leafy vegetables including spinach, cabbage, tomatoes, sweet potatoes, papaya, watermelon, orange, grapefruit, and mango.

Recommended dosage:
Children from 1-3 years: 1000 IU or 300 mcg/day
Children 4-8 years: 1333 IU or 400 mcg/day
Children 9-13 years 2000 IU or 600 mcg/day
Men above 14 years of age 3000 IU or 900 mcg/day and women above 14 years of age 2333 IU or 700 mcg/day. 

Precautions

If you get too much vitamin A, you can become sick. Large doses of vitamin A can also cause birth defects. Babies and children are more sensitive to vitamin A, and can become sick after taking smaller doses of vitamin A or vitamin A-containing products such as retinol.

Always consult your health care provider before starting a supplement therapy