What is Vitamin A?

Vitamin A is fat-soluble, stored in body fat. Although not necessary to intake every day, Vitamin A is vital to the body. 90% of it is stored in liver. Vitamin A is found in two forms - Retinol (preformed Vitamin A) or Retinoids (beta-carotene).

Where does Vitamin A come from?

Vitamin A can be found in two principal forms in foods:

• Retinol, the form of vitamin A absorbed when eating animal food sources, is a yellow, fat-soluble substance. Since the pure alcohol form is unstable, the vitamin is found in tissues in a form of retinyl ester. It is also commercially produced and administered as esters such as retinyl acetate or palmitate.^[1]
• The carotenes Alpha-Carotene, Beta-Carotene, Gamma-Carotene; and the xanthophyll beta-cryptoxanthin (all of which contain beta-ionone rings), but no other carotenoids, function as provitamin A in herbivores and omnivore animals, which possess the enzyme beta-carotene 15,15'-dioxygenase in the intestinal mucosa to cleave and convert provitamin A to retinol.^[2]

What is the importance of vitamin A?

Vitamin A, a fat-soluble vitamin, plays essential roles in vision, growth, and development; the development and maintenance of healthy skin, hair, and mucous membranes; immune functions; and reproduction.

Who needs it and what are some symptoms of deficiency?

According to recent surveys by the U.S. Department of Agriculture (USDA), the average intake of vitamin A (and carotene) by an American adult is adequate. Eating a variety of foods that contain vitamin A (and carotene) is the best way to get an adequate amount. Healthy individuals who eat a balanced diet rarely need supplements. In fact, too much vitamin A can be toxic. Select foods that contain excellent to good sources of vitamin A each day.

How much should be taken? Are there side effects?

A tablespoon (13.6 g) of cod liver oil contains 136% of the UL for preformed vitamin A (retinol). Vitamin A accumulates in the liver, and can reach harmful levels sufficient to cause hypervitaminosis A. Pregnant women may want to consider consulting a doctor when taking cod liver oil because of the high amount of retinol.

Fatty acid oxidation and environmental toxins content are reduced when purification processes are applied to produce refined fish oil products.

The RDA for males is 5000 IU (1.5mg), females 4000 IU. Vitamin A in excess of 50,000 IU can be toxic, causing damage in the body. Stick to the RDA and you'll better off than if you take to much or too little.

Recent Studies

Vitamin A since its discovery in 1816 continues to be studied for its properties in accordance with human health. So research continues today with its effects on many prenatal as well as elderly diseases and life complications due to cellular health, diet, and environmental conditions.

References:

• Wikipedia
• Meschino Health. "Comprehensive Guide to Vitamin A". Archived from the original on 15 May 2013. Retrieved 1 May 2012.
• DeMan J (1999). Principles of Food chemistry (3rd ed.). Maryland: Aspen Publication Inc. p. 358. ISBN 978-0834212343.

Other Anti-Oxidant, Vitamin & Mineral Categories

• Health & Wellness
• Multivitamins
• Antioxidants
• Vitamin A
• Vitamin B
• Vitamin C
• Vitamin D
• Vitamin E
• CoQ10
• ALA
• Beta Carotene
• Grape Seed
• Calcium
• Iron
• Magnesium
• Potassium
• Zinc