Found in animal products, vegetables and fruits, the natural sources of vitamin A are plentiful. However, for those that are unable to get adequate levels of vitamin A from their diet, nutritional supplements are another source of this essential nutrient.
Two Main Sources of Vitamin A: Animal and Plant
There are two main sources of vitamin A, animal sources and plant sources. Known as retinol, animal sources of this essential vitamin contain preformed vitamin A. Vegetable sources contain carotenoids, such as beta-carotene, which is converted to retinol by the body.
Vitamin A from Animal Sources
Vitamin A that comes from animal sources is well absorbed and used more efficiently by the body then other sources of the vitamin. The two main sources of vitamin A from animal products are beef liver and turkey giblets. Other sources of this fat soluble vitamin include:
- Chicken liver
- Cod liver oil
- Fish oil
- Liver sausage, such as Braunschweiger and liverwurst
- Canned beef stew
- Fortified margarine
- Whole milk
- Fortified skim milk
- Fortified low fat dairy products
- Fortified dried powdered milk
- Fortified breakfast cereal
In the United States most skim milk, low-fat dairy products and powdered milk are generally fortified with vitamin A. This is done because the vitamin is removed along with the fat. Margarine is fortified with vitamin A in order to give it the same vitamin A content as butter.
Plant Sources of Vitamin A
The vitamin A that is found in plant sources is known as provitamin A carotenoid, or carotenes. These must be converted by the body into vitamin A, or retinol, before they can be used. This conversion takes place in the upper intestinal tract. Once the carotenes enter the upper intestinal tract, they are converted to vitamin A by the actions of fat splitting enzymes and bile salts. This form of vitamin A is water soluble and cannot be stored by the body. Of all of the various carotenes, beta-carotene is the one that is most easily converted to vitamin A.
Plant sources of vitamin A include many fruits and vegetables that have rich, deep, intense color. The more intense the color of the vegetable or fruit, the more beta-carotene it contains. Plant sources of carotenes include:
- Sweet potatoes
- Winter squash
- Pink Grapefruit
- Beet greens
- Dark green leafy vegetables
Tips to Get the Most Vitamin A from Your Vegetables and Fruits
Following a few simple guidelines will help you to get the maximum amount of vitamin A from your fruits and vegetables.
- Choose fruits and vegetables that have rich, bright or deep colors.
- Eat your fruits and vegetables raw as often as possible.
- Lightly steam vegetables.
- Except for winter squash and sweet potatoes, store your vegetables and fruits in the refrigerator making sure to keep them covered.
Vitamin A Nutritional Supplements
In the United States, most people do not need to take a vitamin A supplement as they receive a sufficient amount of it in their diets. The exceptions are those that have poor diets, suffer from a disease that causes malabsorption or have obstructive jaundice and their body is unable to produce bile which is needed for the absorption of vitamin A.A fat soluble vitamin, vitamin A is stored in the body's liver and fat tissues. The body of a healthy person with a good nutritional diet stores enough of this vitamin to last for several months if they were suddenly deprived from having foods containing the vitamin. However, if a person's diet contains an excessive amount of vitamin A, the excess builds up in the liver. This accumulation can be very dangerous, causing a toxic reaction. Before adding a vitamin A supplement to your diet, it is best to check with your medical practitioner.
By including sources of vitamin A in your diet that supply the daily recommended amounts of this important nutrient, you are helping to keep your body functioning in optimal health.