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:
- Plays an essential role in vision
- Plays an important role in cell differentiation and cell division
- Helps in the formation and maintenance of healthy skin and hair
- Helps with proper bone growth and tooth development
- Helps the body regulate the immune system
- Plays an essential role in the reproduction process for both men and women
The recommended daily dietary allowance for vitamin A is measured in micrograms (mcg) of Retinol Activity Equivalents (RAE).
Vitamin A Deficiency
Vitamin A deficiency is rare in the US, but it is common in developing countries. Here are some of the symptoms:
- Night blindness
- Decreased resistance to infections
- Decreased growth rate
Vitamin A Toxicity
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:
- Blurred vision
- Poor coordination
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
The following foods contain carotenoids, which the body converts into vitamin A.
Populations at risk for vitamin A deficiency
The following populations may be at risk for vitamin A deficiency and may require a supplement:
- People with a reduced ability to absorb dietary fat. Because vitamin A is a fat-soluble vitamin, fat is required for its absorption. Some conditions that can cause fat malabsorption include Crohn's disease, cystic fibrosis, celiac disease, pancreatic enzyme deficiency, and liver disease.
- Children living in developing countries.
Tips for Increasing Your Vitamin A Intake:
Here are some tips to help increase your intake of vitamin A:
- Pack cut carrots in your lunch for an afternoon snack.
- Slice a peach, mango, or apricot on to your breakfast cereal or oatmeal.
- Substitute a sweet potato for your baked potato.
- Eat fruits and vegetables raw whenever possible. Vitamin A can be lost during preparation and cooking.
- Steam vegetables, and braise, bake, or broil meat instead of frying. This will help retain some of the vitamin content.
- Reviewer: Brian Randall, MD
- Review Date: 02/2013 -
- Update Date: 02/07/2013 -