by Jose Juan Gutierrez

Created on: April 13, 2011

Facts about vitamin A

Vitamin A is one of the four fat-soluble vitamins essential in many vital functions in the body, including growth and repair of tissues and the formation of bones and teeth. It acts as an antioxidant by preventing free radicals from producing cellular damage. Appropriate amounts of vitamin A are important for maintaining good eyesight. They´re also necessary for keeping in optimum condition the skeletal, reproductive, and respiratory systems, as well as the immune system.

Adequate amounts of vitamin A are essential for maintaining the proper functionality of the eye retina, reducing the risk of acquiring age-related macular degeneration (AMD), which is responsible for causing blindness in the elderly. The evidence suggests that sufficient levels of vitamin A in the form of carotenoids can reduce the risk of cancer, heart attack, and stroke, as well as immune system disease.

There are two principal forms of vitamin A. Retinoids, which are the active types, are found in animal foods, including meat, milk, and eggs, being liver particularly high in vitamin A, as it serves as the storage place, providing small doses of this vitamin to the body in an as needed basis.

Carotenoids, which are the precursor forms of vitamin A, are principally found in the orange yellow, and red pigments of fruits, vegetables, and leafy green foods such as carrots, spinach, pumpkins, peaches, sweet potatoes, cantaloupes, winter squash, collard greens, and turnip greens. Unlike canned food, fresh foods have the highest concentrations of carotenoids.

Alpha and beta carotene, including other lesser known carotenoids, can be changed to vitamin A in the small intestine, reducing the risk of an overdose as with the active type. Excess beta-carotene, unlike vitamin A, is not toxic when taken in excessive amounts, as the excessive amounts are stored in the body in an as-needed basis.

The deficiency of vitamin A in the body may include poor immune system function, loss of appetite, rashes, hair loss, dry skin, visual difficulties, and fatigue. Deficiencies are most frequent in malnourished people, including the chronically ill, alcoholics, those who are not absorbing fat appropriately, people taking medication, and people with type 1 diabetes.

Overdose of vitamin A can occur when taking more than the recommended doses of the active form. Excessive amounts accumulate in the liver and fatty tissues, producing bone and joint pain, dry lips and skin, liver and spleen enlargement, vomiting, diarrhea, blurry and double vision, irritability, fatigue, and headaches.  Excessive doses of vitamin A can cause birth defects as well. A doctor should be consulted if any of these symptoms occurs.

Taking acceptable doses of zinc, selenium, as well as vitamins C and E enhances the absorption of vitamin A and carotenoids. A small amount of dietary fat is also effective at the absorption of vitamin A. Eating a wide variety of fruits and vegetables, as well as balancing your diet with rich green leafy foods will assure you get the right amounts of vitamin A in your body.

Sources:

medlinePlus

University

Learn more about this author, Jose Juan Gutierrez.
Click here to send this author comments or questions.