Overview & Description
Vitamin A is a fat-soluble vitamin which means it can be dissolved in fat. Vitamin A is carried through the body by fat. The body can store this type of vitamin in fat tissue. Getting too much can be harmful.
Vitamin A can be stored in the fat tissues of the body. This can pose a problem for people taking extra doses of vitamin A. High doses can be toxic and cause symptoms such as the following:
headaches
dry and scaly skin
liver damage
bone and joint pain
vomiting or lack of appetite
abnormal bone growth
nerve damage
birth defects
In most cases, only levels 10 times the RDA (far more than a person could get through diet alone) have been linked with these symptoms. Vitamin A cannot reach toxic levels unless a person is taking extra doses. Carotenoids are not converted to vitamin A fast enough to increase the amount of vitamin A stored in the body. Beta-carotene is NOT toxic to the body.
Getting too little vitamin A can cause side effects too. Symptoms of significant deficiency include:
lowered resistance to infections
problems with getting pregnant
poor growth
improper tooth formation
rough, dry, and pimply skin
digestive problems
night blindness
eye disease, including xerophthalmia (zear-off-thal-me-ah), a condition in which the clear covering of the eye known as the cornea becomes dry and dull
Vitamin A is an important fat-soluble vitamin. Eat a variety of fruits, vegetables, lean meats, and fortified dairy products to ensure optimal intake of vitamin A. Read food labels to help choose foods with vitamin A content.
Information
Vitamin A is usually measured in retinol equivalents, also called RE. The Recommended Dietary Allowance, called RDA, for vitamin A for adult men, from age 11 on, is 1,000 RE per day. Women, from age 11 on, should get 800 RE per day. There is no increase of vitamin A requirements during pregnancy but lactating women need about 500 RE or more per day.Vitamin A can be stored in the fat tissues of the body. This can pose a problem for people taking extra doses of vitamin A. High doses can be toxic and cause symptoms such as the following:
In most cases, only levels 10 times the RDA (far more than a person could get through diet alone) have been linked with these symptoms. Vitamin A cannot reach toxic levels unless a person is taking extra doses. Carotenoids are not converted to vitamin A fast enough to increase the amount of vitamin A stored in the body. Beta-carotene is NOT toxic to the body.
Getting too little vitamin A can cause side effects too. Symptoms of significant deficiency include:
Vitamin A is an important fat-soluble vitamin. Eat a variety of fruits, vegetables, lean meats, and fortified dairy products to ensure optimal intake of vitamin A. Read food labels to help choose foods with vitamin A content.
Functions and Sources
What food source is the nutrient found in?
Vitamin A can come from animal sources such as:This form of Vitamin A is called retinal or retinol.
Vitamin A is also found in plants. This form is called carotenoids. Substances such as beta-carotene are converted from carotenoids into vitamin A in the body. Beta-carotene is one of the most common carotenoids. Carotenoids are pigments found in deep orange, red, and yellow fruits and vegetables. They are also found in many dark-green leafy vegetables, such as:
How does the nutrient affect the body?
Vitamin A helps develop and maintain healthy growth in the cells and almost all the parts of the body. It is especially key for proper night vision, but is also needed for the health of a person's:Vitamin A plays a key role in the immune system by helping protect from infections. Beta-carotene is an antioxidant. It has been studied for its role in cancer and heart disease protection. Antioxidants help fight free radicals. Free radicals are oxygen by-products produced when body cells burn oxygen. A build up of free radicals can damage body cells and tissues.
Attribution
Author:Clare Armstrong, MS, RD
Date Written:
Editor:Crist, Gayle P., MS, BA
Edit Date:09/27/02
Reviewer:Kathleen A. MacNaughton, RN, BSN
Date Reviewed:09/26/02
Somer, E., MA, RD. & Health Media of America. (1995). The Essential Guide To Vitamins and Minerals (2nd ed.). New York: HarperCollins Publishers, Inc.
Duyff, R., MS, RD, CFCS. (1996). The American Dietetic Association's Complete Food & Nutrition Guide. Minnesota: Chronimed Publishing.
Date Written:
Editor:Crist, Gayle P., MS, BA
Edit Date:09/27/02
Reviewer:Kathleen A. MacNaughton, RN, BSN
Date Reviewed:09/26/02
Sources
Mahan, K, MS, RD, CDE & Escott-Stump, S., MA, RD, LDN. (2000). Krause's Food, Nutrition, & Diet Therapy (10th ed.). Pennsylvania: W.B. Saunders Company.Somer, E., MA, RD. & Health Media of America. (1995). The Essential Guide To Vitamins and Minerals (2nd ed.). New York: HarperCollins Publishers, Inc.
Duyff, R., MS, RD, CFCS. (1996). The American Dietetic Association's Complete Food & Nutrition Guide. Minnesota: Chronimed Publishing.
