Vitamin A is a vitamin, a group of organic chemicals including retinal and several carotenoids. The human body does not make these chemicals, and must take them from food. Carrots and liver are both rich in vitamin A. Many parts of the body need vitamin A. For example, vitamin A helps sight and is good for the immune system. It is also important for a growing embryo.
Too little vitamin A is dangerous to health. People who do not get enough of the vitamin may lose the ability to see in poor light and suffer from a weakened immune system. They may also have problems with memory, because vitamin A is important for the brain. People with malnutrition often have too little vitamin A. This is common in poor countries.
Too much vitamin A is also dangerous to one's health. This is because, vitamin A is not soluble in water, and the human body can not get rid of the excess vitamin A easily through urination. Too much vitamin A can make someone very sick. People may get too much vitamin A from taking too many vitamin pills or from eating too much rich food like liver.
If a pregnant woman has too little or too much vitamin A it may cause birth defects in the unborn baby.
vitamin A (retinol ) contain nine conjugated hydrocarbon chain. Vitamin is also necessary for the growth and maintenance of tissues.
- "Dietary Supplement Fact Sheet: Vitamin A and Carotenoids". Ods.od.nih.gov. 2006-04-23. Retrieved 2010-08-20.
- Anderson J, Young L. "Fat-Soluble Vitamins". Colorado State University, Cooperative Extension. Retrieved 20 May 2007.