Vitamin A - Why Do We Need It?
Like all of the other vitamins and minerals, vitamin A plays an essential role in human health and well-being. Although retinol is widely believed to be the equivalent of vitamin A, it's only part of a family of fat-soluble vitamins. Nevertheless, like the other members of the group, it's necessary for the smooth functioning of the many systems that make our bodies get up and go.
Vitamin A is essential for good vision, bone development, cell differentiation, and cell division. It also boosts the immune system by producing white blood cells, which are instrumental in fighting off or destroying pathogens that harm the body or cause infections and diseases. It protects the body from bacteria and viruses in another way: by strengthening the linings of the intestinal, urinary, and respiratory tracts, as well as the linings of the eyes, thereby making them more resistant to bacterial invasions. In a similar way, it keeps the skin and mucous membranes strong and healthy and more able to prevent the entry of pathogens into the body.
Retinol is perhaps the most popular form of this vitamin; other forms include retinal and retinoic acid. It is important for skin and eye health and is found in foods such as meat (particularly liver), milk, and fortified products. Carotenoids, on the other hand, are pigments in fruits and vegetables from which the vitamin can be derived. According to the 2000 National Health and Nutrition Examination Survey, examples of plant foods that are rich in carotenoids are sweet potatoes, carrots, and spinach.
Deficiency in retinol and other A vitamins is not that prevalent in Western countries, but it is a big problem in developing nations. Hundreds of thousands of children go blind each year in poor countries because of nutritional deficiency. In addition, they become more prone to dying from diseases like measles and pneumonia because their immune systems have become too weak to resist pathogenic attacks.
Make sure that you get the recommended daily allowance of this vitamin in order to maintain your health. People of different ages need different amounts daily -- with pregnant and breastfeeding women needing more. However, remember that taking too much of this vitamin can produce toxic results. Acute poisoning is manifested by symptoms like dizziness, vomiting, and headache, while longer-term effects include liver disease, birth defects, and loss of bone mineral density.
Eating foods that are rich in vitamin A will generally enable you to get the doses you need so that you don't have to take supplements for this vitamin. However, if you have special health needs that require you to ingest more of this vitamin, ask your doctor first before taking supplements to ensure that you're getting the right dose.
