What is Vitamin A, and how do we get it
Vitamin A is a generic term for a large number of related compounds. Retinol and retinal are often referred to as preformed vitamin A. Retinal can be converted by the body to retinoic acid, the form of vitamin A known to affect gene transcription. Retinol, retinal, retinoic acid, and related compounds are known as retinoids. Beta-carotene and other carotenoids that can be converted by the body into retinol are referred to as provitamin A carotenoids. Hundreds of different carotenoids are synthesized by plants, but only about 10 % of them are provitamin A carotenoids.
Why Vitamin A is an important nutrient
Vitamin A does much more than help you see in the dark. Vitamin A stimulates the production and activity of white blood cells, takes part in remodeling bone, helps maintain the health of endothelial cells (those lining the body's interior surfaces), and regulates cell growth and division. Vitamin A helps regulate the immune system, which helps prevent and combats infections by producing white blood cells that destroy harmful bacteria and viruses and helping lymphocytes (a type of white blood cell that help us fight infections) function more vigorously. Vitamin A also plays a significant role in vision, bone growth, reproduction, cell division and cell differentiation. It helps to maintain the membranous linings of the eyes and the respiratory, urinary, and intestinal tracts. Those linings protect the organs from being invaded by bacteria and viruses. At high levels preformed Vitamin A can be toxic, it is stored in the body, as are the other fat soluble vitamins
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
Vitamin A : Beta Carotene
Beta-carotene, which consists of two molecules of retinal linked at their ends, is also referred to as the provitamin form of vitamin A, a precursors, which the body can turn into vitamin A. In contrast to preformed vitamin A, beta-carotene is not toxic even at high levels of intake. The body can form vitamin A from beta-carotene as needed, and there is no need to monitor intake levels, as there is with preformed vitamin A. Therefore, it is preferable to choose a vitamin supplement that has all or the vast majority of its vitamin A in the form of beta-carotene. Another reason to avoid too much preformed vitamin A is that it may interfere with the beneficial actions of vitamin D. Current medical research shows that foods rich in Beta Carotene will help reduce the risk of lung cancer & certain oral cancers. Unlike Vitamin A from fish liver oil, Beta Carotene form of Vitamin A is non-toxic.
In the next article I will discuss the benefits of the Vitamin Bs