by Mary Calvagna, MS
Vitamin A, also called retinol, is a fat-soluble vitamin. Our bodies store fat-soluble vitamins in the liver and fatty tissues. The active form of vitamin A is found in animal tissue. Red, orange, and dark green vegetables and fruits contain precursor forms of vitamin A called carotenoids. Our bodies can convert some of these carotenoids into vitamin A.
Here are some of vitamin A's functions:
The recommended daily dietary allowance for vitamin A is measured in micrograms (mcg) of Retinol Activity Equivalents (RAE).
Vitamin A Deficiency TOP
Vitamin A deficiency is rare in the US, but it is common in developing countries. Here are some of the symptoms:
Vitamin A Toxicity TOP
As a fat-soluble vitamin, vitamin A is stored in the body and not excreted in the urine like most water-soluble vitamins. Therefore, it is possible for vitamin A to accumulate in the body and reach toxic levels. For adults, the tolerable upper intake level (UL) for vitamin A from dietary sources and supplements combined is 3,000 RAE daily. It is less in children. Symptoms of toxicity include the following:
Too much vitamin A can cause severe birth defects. Pregnant women, and those who may become pregnant, should not take too much vitamin A from dietary sources and supplements.
Major Food Sources TOP
The following foods contain carotenoids, which the body converts into vitamin A.
Health Implications TOP
Populations at risk for vitamin A deficiency
The following populations may be at risk for vitamin A deficiency and may require a supplement:
Tips for Increasing Your Vitamin A Intake: TOP
Here are some tips to help increase your intake of vitamin A:
Academy of Nutrition and Dietetics
American Society for Nutrition
Dietitians of Canada
Health Canada Food and Nutrition
Dietary Supplement Fact Sheet: Vitamin A. Office of Dietary Supplements website. Available at: http://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/. Updated July 25, 2012. Accessed February 7, 2013.
Fairfield KM, Fletcher RH. Vitamins for chronic disease prevention in adults: scientific review. JAMA. 2002;287(23):3116-26.
Vitamin A deficiency. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what. Updated November 22, 2011. Accessed February 7, 2013.
Vitamin A overdose. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what. Updated June 22, 2010. Accessed February 7, 2013.
Last reviewed February 2013 by Brian Randall, MD
Last Updated: 2/7/2013