Retinol is quickly and easily absorbed by our body. It’s found in animal products like butter, eggs, cod liver oil and fortified breakfast cereals. Carotenoids, or provitamin A, need to be converted to vitamin A once inside our body. Unlike retinol, carotenoids are found in plant foods, namely fruits and vegetables. The most common one is beta-carotene.
Vitamin A has many functions to perform and we can start by looking at the eyes. Vitamin A maintains healthy vision through the retina. The retina of the eye converts what we see into images and sends these images to our brain. When the sun goes down, the retina switches to night vision and gives us the ability to see in a darkened environment. We need vitamin A to maintain healthy vision for both day and night.
Vitamin A is also involved in cell development. Our body is a mass of cells; they constitute every component of our body. Skin cells, blood cells, liver cells, and everything in between. Each cell starts off the same, but as it grows, it forms into a specialized cell with a specialized function. Vitamin A forms a part of this process; it helps each cell develop into what it needs to be. The proper regeneration of skin cells also makes for a healthy complexion. An ample intake of vitamin A means our skin cells can be turned over and replaced with plenty of new and healthy ones.
Vitamin A also helps our immune system to be the best that it can be. It helps to build white blood cells, which are at the heart of our immunity, as well as maintain other cells that are crucial to a fit and fighting immune system. As well as defense, vitamin A also helps with growth and development, especially during high growth periods like pregnancy.
Provitamin A, or the carotenoids, also have another function to perform. As well as the aforementioned tasks, carotenoids are a distinguished antioxidant with free radical fighting properties. Before these carotenoids are converted to vitamin A in our body, they perform antioxidant duties and this may help in the prevention of certain cancers.
A moderate vitamin A deficiency effects the eyes and may cause night blindness. As the deficiency progresses, the eyes start to show visual signs and develop what is called Bitot’s spot, a white ‘spot’ visible on the eye’s surface. An extreme deficiency can cause xeropthalmia; a condition that results in dry eyes, with scarring, ulcers and eventually blindness.
Children with a vitamin A deficiency are effected by all of the above, with the addition of impaired growth and development. A pregnant women lacking in vitamin A, passes the effects onto her unborn baby. It impairs the proper growth and development of the baby, and this causes permanent damage.
Vitamin A deficiency is still a problem in developing countries where the intake of green and orange vegetables, and fruit and dairy is limited.
An overdose in certain nutrients can have just as many complications as a deficiency. Vitamin A is one of them and it's called hypervitaminosis A. Vitamin A is a fat soluble vitamin that is stored in our liver. Continued large doses of the retinol form, like cod liver oil, supplements, or retinol medications, are quickly and easily absorbed within just a few hours of consumption. But unlike the quick absorption into our body, clearance by the liver is slow and the vitamin then accumulates. This can have detrimental effects for the liver and lead to toxicity. Symptoms include dry, flaky skin, nausea, headaches and a loss of appetite. A severe toxicity can cause liver damage or even a coma.
An excessive intake of vitamin A in pregnant women can cause serious birth defects in the baby. So unless instructed by a health care practitioner or physician, vitamin A supplementation during pregnancy is not advised in healthy individuals.
products fortified with retinol