Vitamin A, or retinol, is one of the fat-soluble vitamins essential for the body. It is found as retinol in mammals and pro-vitamin A (beta carotene) in plants. Its actions in the body allow, among other things, to preserve visual acuity and strengthen the immune system.
Characteristics of vitamin A:
- Fat-soluble vitamins are essential for vision and the immune system
- Found as pro-vitamin A (beta carotene) in certain plants
- Presents as retinol in large quantities in organ meats
- Beta carotene is a powerful antioxidant and promotes skin pigmentation
- In excess, beta carotene could have harmful consequences on health
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. Foods of animal origin, therefore, contain vitamin A in the form of retinol. In foods of plant origin, we find vitamin A in the form of carotenes, which are precursors of vitamin A, called pro-vitamin A. In this sense, have said that beta carotene is pro-vitamin A.
Vitamin A and sight
Vitamin A plays an essential role in the quality of vision. It allows, in fact, the triggering of the nerve impulse at the level of the optic nerves. A sufficient intake of vitamin A thus reduces the risk of cataracts and macular degeneration.
Antioxidant
Carotenes, and beta-carotene, in particular, are molecules with strong antioxidant power. In the body, antioxidants make it possible to fight against cellular aging and oxidative stress. In other words, they neutralize the damage caused by free radicals and participate in maintaining a healthy organism and a robust immune system.
Vitamin A and skin
Retinol participates in the differentiation and renewal of the body’s cells, particularly the skin and mucous membranes. We also often stress the benefits of foods rich in carotene on the quality of the skin. Indeed, vitamin A is a precursor of melanin responsible for the pigmentation of the skin. Thus, a good supply of vitamin A and beta carotene makes it possible 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 primarily found in organ meats.
20 foods that are sources of vitamin A
| Food | Portions | (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 the peel), baked | 100 g (1 medium) | 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 green kale | 125 ml (1/2 cup) | 468 µg |
| Cabbage, cooked | 125 ml (1/2 cup) | 408 µg |
| Boiled beet leaves | 125 ml (1/2 cup) | 291 µg |
| Boiled turnip greens | 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, marinated | 100 g | 258 µg |
| Boiled dandelion leaves | 125 ml (1/2 cup) | 190 µg |
| Melon | 1/4 of melon | 143 µg |
| Cooked pakchoi or bok choy | 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 |
* EAR: Equivalent of retinol activity
How to properly use vitamin A (beta carotene)?
Use of vitamin A
Daily Vitamin A Requirements
| Recommended nutritional intake (ANC) | |
| Babies 0-6 months | 400 µg * |
| Babies 7-12 months | 500 µg * |
| Infants 1-3 years | 300 µg |
| Children 4-8 years old | 400 µg |
| Boys 9-13 years old | 600 µg |
| Girls 9-13 years | 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 | 700 µg |
| Men 50 years and over | 900 µg |
| Women 50 years and over | 700 µg |
| Pregnant women | 770 µg |
| Breastfeeding women | 1,300 µg |
Adverse effects of vitamin A
Consequences of vitamin A deficiency
Vitamin A deficiency is much more common than you might think, especially in disadvantaged populations. It mainly causes vision disorders that can range from a simple alteration of the cornea to total blindness. Vitamin A deficiency can also be responsible for decreased immune defenses and, therefore, greater susceptibility to infections.
Consequences of excess vitamin A
Interactions with other nutrients
Lipids have a beneficial effect on the absorption of vitamin A regardless of its form (retinol or carotenes). It is therefore recommended to consume foods rich in vitamin A within 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 even zinc.
Chemical properties
Vitamin A is one of the fat-soluble vitamins. In the body of mammals, it exists in different forms: retinol, retinal, retinoic acid, etc.
Plants contain carotenes, including beta carotene, precursors of vitamin A. One molecule of beta-carotene gives rise to two molecules of vitamin A. The crude formula of beta carotene is C40H56, its molar mass 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 color and prevent oxidation.
Historical
Vitamin A is the very first to have been discovered in 1913, so it bears the first letter of the alphabet. It was identified for the first time after studying a cod liver.
