Vitamin A, or retinol, is one of the fat-soluble vitamins essential to the body. It is found as retinol in mammals and as provitamin A (beta carotene) in plants. Its actions in the body help, among other things, to preserve visual acuity and strengthen the immune system.
Characteristics of vitamin A:
- Fat-soluble vitamin important for vision and the immune system
- Found as pro vitamin A (beta carotene) in some plants
- Present as retinol in large quantities in offal
- Beta carotene is a powerful antioxidant and promotes skin pigmentation
- In excess, beta carotene could have harmful consequences on health
Why eat foods rich in vitamin A?
Vitamin A: benefits and roles in the body
Vitamin A, beta carotene, retinol and pro vitamin A: what are the differences?
In the body of humans and animals, vitamin A is found in the form of retinol, retinal or retinoic acid. Food of animal origin therefore contains vitamin A in the form of retinol. In foods of plant origin, vitamin A is found in the form of carotenes, which are precursors of vitamin A, known as pro-vitamin A. In this sense, it has been said that beta carotene is a pro vitamin A.
What is the purpose of vitamin A?
Vitamin A and sight
Vitamin A plays an essential role in the quality of vision. It allows, in fact, the triggering of nerve impulses in the optic nerves. Adequate vitamin A intake thus reduces the risk of cataracts and macular degeneration.
Carotenes, and beta-carotene in particular, are molecules with powerful antioxidant power. In the body, antioxidants help to fight against cellular ageing and oxidative stress. In other words, they neutralize the damage caused by free radicals and help maintain a healthy body and an effective immune system.
Vitamin A and skin
Retinol helps to differentiate and renew the body’s cells, particularly the skin and mucous membranes. The benefits of carotene-rich foods on skin quality are also often highlighted. Indeed, vitamin A is a precursor of melanin responsible for skin pigmentation. Thus, a good supply of vitamin A and beta carotene helps to prepare the skin for the sun, protect the skin cells against external aggressions and promote their renewal.
Foods rich in vitamin A
In the diet, various foods are sources of retinol or carotenes. Carotenes are found mainly in orange fruits and vegetables and leafy green vegetables, while retinol is found mainly in offal.
20 foods that are sources of vitamin A
|Foodstuffs||Portions of food||(µg)|
|Turkey offal, braised or simmered||100 g||10,737 µg|
|Beef liver, sautéed or braised||100 g||7,744-9,442 µg|
|Chicken offal, braised or simmered||100 g||1,753-3,984 µg|
|Carrot juice||125 ml (1/2 cup)||1,192 µg|
|Sweet potato (with skin on), baked in the oven||100 g (1 average)||1,096 µg|
|Canned pumpkin||125 ml (1/2 cup)||1,007 µg|
|Cooked carrots||125 ml (1/2 cup)||653-702 µg|
|Boiled spinach||125 ml (1/2 cup)||498 µg|
|Cooked kale||125 ml (1/2 cup)||468 µg|
|Cooked cabbage||125 ml (1/2 cup)||408 µg|
|Boiled beet leaves||125 ml (1/2 cup)||291 µg|
|Boiled turnip leaves||125 ml (1/2 cup)||290 µg|
|Cooked winter squash||125 ml (1/2 cup)||283 µg|
|Lettuce (romaine, mesclun, curly)||250 ml (1 cup)||219-266 µg|
|Atlantic herring, pickled||100 g||258 µg|
|Boiled dandelion leaves||125 ml (1/2 cup)||190 µg|
|Melon||1/4 dof melon||143 µg|
|Pak-choi or bok choy cooked||125 ml (1/2 cup)||190 µg|
|Raw or cooked red pepper||125 ml (1/2 cup)||103-124 µg|
|Tomato or vegetable juice||125 ml (1/2 cup)||100 µg|
*RAE: Retinol activity equivalent
How to use vitamin A (beta carotene) properly?
Use of vitamin A
Daily vitamin A requirements
|Recommended Dietary Allowance (RDA)|
|Babies 0-6 months||400 µg*|
|Babies 7-12 months||500 µg*|
|Babies 1-3 years old||300 µg|
|Children 4-8 years old||400 µg|
|Boys 9-13 years old||600 µg|
|Girls 9-13 years old||600 µg|
|Boys 14-18 years old||900 µg|
|Girls 14-18 years old||700 µg|
|Men 19-50 years old||900 µg|
|Women 19-50 years old||700 µg|
|Men 50 years and over||900 µg|
|Women 50 years and over||700 µg|
|Pregnant women||770 µg|
|Nursing Women||1,300 µg|
* Adequate contributions
Food supplements in beta carotene or vitamin A
Many dietary supplements are made with vitamin A or its precursors (including beta carotene). A vitamin A supplement may be indicated to prevent or treat eye diseases (retinitis, macular degeneration, cataracts, etc.). These supplements are also particularly appreciated for their antioxidant capacity, which supports the immune system and prevents certain diseases. Finally, as summer approaches, beta carotene is widely used to activate melanin synthesis and promote tanning. Be careful, however, if vitamin A intake has few consequences, beta-carotene intake can be dangerous in the long term. Ask your doctor’s advice before considering supplementation.
Adverse effects of vitamin A
Consequences of vitamin A deficiency
Vitamin A deficiency is much more frequent than we think, especially in disadvantaged populations. It mainly causes vision problems that can range from a simple alteration of the cornea to total blindness. Vitamin A deficiency can also be responsible for a decrease in immune defences and therefore a greater sensitivity to infections.
Consequences of excess vitamin A
Vitamin A is stored in the liver, excess can lead to hepatomegaly (large liver) and various digestive disorders (nausea, diarrhea, etc.). On the skin, an overdose can cause irritation and itching. In children, there is a risk of overthickening of bone tissue. In pregnant women, an excess of vitamin A can lead to fetal malformations. Fortunately, and except in exceptional cases (liver pathologies, excessive intake of supplements, etc.), overconsumption is extremely rare.
Interactions with other nutrients
Lipids have a beneficial effect on the absorption of vitamin A whatever its form (retinol or carotenes). It is therefore recommended to consume foods rich in vitamin A as part of a complete meal. In addition, the antioxidant action of beta carotene is increased in the presence of other antioxidant molecules such as vitamin C, vitamin E, selenium or zinc.
Be careful, for smokers, taking beta-carotene food supplements is not recommended. Indeed, the combination of provitamin A and certain molecules contained in tobacco would increase the risk of developing lung and stomach cancers.
Vitamin A is one of the fat-soluble vitamins. In mammalian organisms, it exists in different forms: retinal, retinal, retinal, retinoic acid, etc.
Plants contain carotenes, including beta carotene, precursors of vitamin A. One molecule of beta-carotene gives birth to two molecules of vitamin A. The gross formula of beta carotene is C40H56, its molecular weight is 536.8726 g/mol. It is the most common form of carotene, it is also a powerful antioxidant and an additive widely used by the food industry to colour and prevent oxidation.
History of the event
History of the nutrient
Vitamin A is the very first to have been discovered in 1913, which is why it carries the first letter of the alphabet. It was first identified after studying a cod liver.
In 1931, P. Karrer finally succeeded in isolating it and precisely defining its chemical structure. However, it was not until 1947 that scientists were able to synthesize it for the first time. Since then, the importance of this vitamin and its precursors for the body’s functioning has been constantly emphasized and investigated.