Primary and Secondary Causes of Vitamin A Deficiency
When talking about the causes of Vitamin A deficiency it is important to distinguish between a primary cause and a secondary cause. The primary cause of Vitamin A deficiency is simply when not enough of the nutrient is eaten. Vitamin A can be found in animal sources such as eggs, liver and cheese. However, the healthiest and best sources of Vitamin A include carrots, broccoli and spinach along with most other brightly colored or dark green fruits and vegetables.
Secondary causes of Vitamin A deficiency are a little more complicated to understand and include problems with the absorption of Vitamin A in the intestines, or the release of Vitamin A by the liver. Vitamin A is a fat-soluble nutrient that is stored in the body, specifically in the liver. If there is a problem with the liver, then symptoms of Vitamin A deficiency can occur because the Vitamin A is not properly released for the body to use. This type of secondary cause of Vitamin A deficiency is most often seen in people who abuse alcohol and have already suffered serious liver damage or have suffered liver damage because of Hepatitis.
The other type of secondary cause of Vitamin A deficiency is a problem with the absorption of the vitamin through the intestinal wall. This can happen for a few different reasons. The most common is damage or disease to the intestinal wall which impairs its ability to absorb many nutrients. Vitamin A deficiency can also occur as a result of zinc deficiency. Zinc is required by the intestines in order to allow Vitamin A into the body, thus a deficiency of zinc can lead to a deficiency of Vitamin A. Finally, since Vitamin A is fat soluble ( and not water soluble), it requires the presence of fat to help it enter the body. People on extremely low fat diets may develop Vitamin A deficiency as the body is not able to absorb the nutrient sufficiently.
Overview of Symptoms of Vitamin A Deficiency
Vitamin A is used by the body in many different, unrelated ways and so the symptoms of a Vitamin A deficiency can vary greatly. It is also important when talking about Vitamin A to realize that many of the symptoms are extremely short term and can be reversed quickly while others can lead lead to permanent damage to the body.
Reversible Short-term symptoms of Vitamin A Deficiency
Probably the most famous use of Vitamin A is in its role with vision. As Vitamin A supplies begin to diminish, low-light vision can be drastically impaired. Vitamin A is also used by the body to repair and construct muscle, so muscle weakness and fatigue are often seen with a deficiency of Vitamin A. And finally with many vitamins, Vitamin A is needed to produce hair and skin, so that even a small deficiency of Vitamin A will result in poor skin quality and dry and brittle hair.
Vitamin A Deficiency and Respiratory Infections
Another major role of Vitamin A is in the maintenance of the membrane lining the lungs and respiratory tract. Without adequate supplies of Vitamin A, the lining will gradually harden and crack. Cracks in the lining allow bacteria and fungus to enter and cause infections. These infections will continue to worsen the longer the person has a deficiency of Vitamin A.
Long-Term Vitamin A Deficiency in the Third World
While our bodies use Vitamin A to enable low-light vision, Vitamin A is also needed for the maintenance and protection of the retina. While very rare in the first world, in many third world countries prolonged deficiencies of Vitamin A results in blindness, normally in the elderly or children. Similarly, in the third world, long-term Vitamin A deficiencies can also lead to disfigurement of children during their growing years. Because Vitamin A is needed for proper bone and muscle growth, a Vitamin A deficiency can cause bones and muscles to not form properly which results in life-long deformities, usually in the arms, hands, legs and feet. These symptoms are rarely seen in more wealthy countries except in cases of child abuse.