Vitamin A Roles

Vitamin A is a fat-soluble vitamin that plays an important role in vision, bone growth, reproduction, cell division, and cell differentiation (in which a cell becomes part of the brain, muscle, lungs, etc.). Vitamin A helps regulate the immune system, which helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses. Vitamin A also may help lymphocytes, a type of white blood cell, fight infections more effectively.

Vitamin A promotes healthy surface linings of the eyes and the respiratory, urinary, and intestinal tracts. When those linings break down, it becomes easier for bacteria to enter the body and cause infection. Vitamin A also helps maintain the integrity of skin and mucous membranes, which also function as a barrier to bacteria and viruses.

Vitamin A Foods

Vitamin A is found in animal foods such as whole eggs, liver, milk, margarine, and fortified ready-to-eat cereals. Also, Vitamin A is abundant in darkly colored fruits and vegetables such as carrots, cantaloupes, sweet potatoes and spinach. Animal sources of vitamin A are well absorbed and used efficiently by the body. Plant sources of vitamin A are not as well absorbed as animal sources.

Vitamin A Deficiency

Night blindness is one of the first signs of vitamin A deficiency. It can contribute to blindness by making the cornea very dry and damaging the retina and cornea. Vitamin A deficiency diminishes the ability to fight infections, and cells lining the lungs lose their ability to remove disease-causing microorganisms, contributing to pneumonia. Excess alcohol intake also depletes vitamin A stores.