Vitamin A - Learn About Vitamins & Minerals
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
What food source is the nutrient found in?
Vitamin A can come from animal sources such as:
- fortified milk
- oils of some fish
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:
- pumpkin and other squashes
- sweet potatoes
How does the nutrient affect the body?
Vitamin A helps develop and maintain healthy growth in the cells
of 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:
- skeletal and soft tissue
- mucous membranes
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.
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:
- 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.
<< Learn More About All Different Types of Vitamins >>