Vitamin A is required by the immune system in several different ways. Vitamin A is called the “anti-infective” vitamin because the human immune system cannot function without it. With millions of children deficient in vitamin A, deaths from common childhood infections such as pneumonia and measles can be greatly reduced with better food or vitamin A supplementation. While childhood vitamin A deficiency is rare in developed countries, it is widespread in southeast Asia and Africa.
VITAMIN A AND MUCOUS MEMBRANES
One of the first lines of defense against infection is the mucous membranes. These mucous membranes line the digestive tract, the lungs and sinuses, the vagina, the eyes, and the urinary tract. Vitamin A is required to maintain the integrity of these vital barriers to infection.
Without vitamin A, certain cells in the mucous membranes, goblet cells, become fewer in number. Goblet cells are needed to produce mucus, which is necessary for all of the mucous membranes. Mucus forms a chemical barrier to gastric acid in the stomach. Mucus also helps eliminate contaminants in the lungs. Mucus forms an important first barrier to invasive microorganisms. With fewer goblet cells, less mucus is produced, as seen in Figure 3-4. This is a problem in the intestines because Figure 3-4 Levels of vitamin A must be maintained for proper absorption of vitamin A. the decreased amount of mucus leads to decreased absorption of nutrients. This leads to diminished vitamin A absorption—leading to a vicious cycle.
How Vitamin A Reduces Risk of Infections
Vitamin A strengthens mucous membranes.
Vitamin A increases mucous secretion.
Vitamin A keeps skin flexible.
Vitamin A is needed in the development of lymphocytes.
Vitamin A is needed for the regulation of the immune system.
VITAMIN A KEEPS SKIN SOFT
When vitamin A is deficient, the skin becomes drier, and can become rough and scaly. This hardening and drying is related to an increase of keratin, a hard and inflexible protein found in fingernails. This hardened skin is less effective as a barrier to infection. This hardening effect from deficient vitamin A is also a problem with the mucous membranes throughout the body.
VITAMIN A INCREASES IMMUNE RESPONSE
Vitamin A has other roles in resistance to infection. Vitamin A plays a central role in the development of lymphocytes, white blood cells that play critical roles in the immune response. Also, activation of the major regulatory cells of the immune system, T-lymphocytes, requires the retinoic acid form of vitamin A.
VITAMIN A AND MUCOUS MEMBRANES
One of the first lines of defense against infection is the mucous membranes. These mucous membranes line the digestive tract, the lungs and sinuses, the vagina, the eyes, and the urinary tract. Vitamin A is required to maintain the integrity of these vital barriers to infection.
Without vitamin A, certain cells in the mucous membranes, goblet cells, become fewer in number. Goblet cells are needed to produce mucus, which is necessary for all of the mucous membranes. Mucus forms a chemical barrier to gastric acid in the stomach. Mucus also helps eliminate contaminants in the lungs. Mucus forms an important first barrier to invasive microorganisms. With fewer goblet cells, less mucus is produced, as seen in Figure 3-4. This is a problem in the intestines because Figure 3-4 Levels of vitamin A must be maintained for proper absorption of vitamin A. the decreased amount of mucus leads to decreased absorption of nutrients. This leads to diminished vitamin A absorption—leading to a vicious cycle.
How Vitamin A Reduces Risk of Infections
Vitamin A strengthens mucous membranes.
Vitamin A increases mucous secretion.
Vitamin A keeps skin flexible.
Vitamin A is needed in the development of lymphocytes.
Vitamin A is needed for the regulation of the immune system.
VITAMIN A KEEPS SKIN SOFT
When vitamin A is deficient, the skin becomes drier, and can become rough and scaly. This hardening and drying is related to an increase of keratin, a hard and inflexible protein found in fingernails. This hardened skin is less effective as a barrier to infection. This hardening effect from deficient vitamin A is also a problem with the mucous membranes throughout the body.
VITAMIN A INCREASES IMMUNE RESPONSE
Vitamin A has other roles in resistance to infection. Vitamin A plays a central role in the development of lymphocytes, white blood cells that play critical roles in the immune response. Also, activation of the major regulatory cells of the immune system, T-lymphocytes, requires the retinoic acid form of vitamin A.
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