Vitamin A, also known as retinol, offers a whole heap of benefits in vision, reproduction, bone development, division of cells and cell differentiation. It also plays significant role in the production of white blood cells. In effect, it strengthens the immune system of the body and aids in fighting against various harmful germs and viruses. Vitamin A offers a healthy subtle sheath in the retina, respiratory tract, urinal tract and intestinal tract areas. Vitamin A deficiencies may cause breaking this sheath - this, in turn, makes it easy for germs to enter into the health system.

Typically, vitamin A can be subdivided into two categories depending on their sources of availability. These two categories are preformed vitamin A and provitamin A carotenoid. Preformed vitamin A can mostly be found from animals such as liver, whole milk and fortified food products. This type is easily absorbed in the form of retinol. Retinol can be converted into retinal and retinoic acid within the body.

Provitamin A carotenoid can be found in colorful fruits and vegetables. Few common forms of this type of vitamin A are beta-carotene, alpha-carotene, and beta-cryptoxanthin. Among all of these forms, beta-carotene can be effectively prepared into retinol.

Animals and animal products are considered as the wise selection for vitamin A sources. It is mainly because of the fact that it is well absorbed and utilized efficiently with the body system. However, plants can also be considered as vitamin A sources, but they can not be well absorbed within the body and may not function effectively as well. Liver, fortified skim milk, cheese, and egg are great vitamin A sources.

Carrot offers generous amount of vitamin A. Whether you take it raw or boiled or as a juice, it offers you plenty amount of vitamin A. Apart from that, you can depend on kale, vegetable soup, apricots with skin, apricot nectar, oatmeal, peas, orange juice, peaches, and pepper.

Vitamin A deficiencies largely depend on regions. The deficiency is quite prominent in developing countries like India; however, it is rarely seen in USA. In the developing regions, a significant number of children become blind every year due to vitamin A deficiencies. On the other hand, vitamin A deficiencies are mostly related to the strict dietary restrictions and excessive alcohol consumption.

Night blindness is one of the most significant conditions occurring as a result of vitamin A deficiencies. Dated back to ancient period, Egyptian civilization also confirmed the usefulness of liver in treating night blindness. Liver is a great source of vitamin A contents. Vitamin A deficiencies contribute to night blindness by turning the cornea very dry and damaging the cornea and retina.

Vitamin A deficiencies may also contribute in weaker immune system. In developing countries, immunization program is thus restricted. The mortality rate is very high due to complications of infectious diseases like measles. Pneumonia is also believed to be caused due to vitamin A deficiency.

Few scientific studies argue that there is a strong relation between beta-carotene and lower risk of cancer. A higher intake of colorful fruits and vegetables may lower the possibilities of lung cancer. However, it is strongly controversial in nature. It is mainly because of the fact that many studies also advocate against the correlation. They conducted research for investigating the significance of beta-carotene supplements in preventing various types of cancer, but could not find any effective result supporting the relevance.

Recent studies are going for finding out the potential adverse effect associated with excess intake of vitamin A supplements. Several researchers have found out that there is a strong correlation between excess intake of vitamin A and weaker bone structure. Hypervitaminosis A is a critical condition referred to the excess storage of vitamin A in the body. Birth defects, abnormalities in liver, declined bone mineral density and CNS disorders are the common adverse effects associated with the excess intake of vitamin A.