The history of vitamin A began in 1913 when scientists discovered a substance critical to the health of adults and children. Fat-soluble retinol received the label “A” – the first letter of the alphabet, and the water-soluble vitamins discovered later began to be designated as “B” and “C”.
Research on the benefits of vitamin A began with foods such as butter and egg yolk. Later it turned out that most retinol is found in the liver of animals (especially cod liver oil). In addition, foods rich in vitamin A are red and yellow vegetables.
Vitamin A – what is it good for?
Vitamin A is essential for the proper functioning of the body’s immune system and the maintenance of a healthy metabolism. In the form of retinol, vitamin A is found in most tissues of the human body (from the skin to the muscles and brain), regulating the healing and growth processes.
First of all, vitamin A is needed to neutralize free radicals and limit their negative effects – this slows down the aging process and the growth of cancer cells. It also enhances the beneficial effects of other antioxidants (both vitamin C and phytonutrients).
In particular, retinol is necessary for skin tissues and mucous membranes to maintain health and recover from damage. The benefit of products with vitamin A is to improve the synthesis of collagen – a building material for the connective tissues of the body.
Vitamin A key points:
- First vitamin discovered
- Needed for brain function and immunity
- Important for maintaining tissue health
- Works in combination with vitamins D, E, and K
Recommended daily values
For men, the daily requirement for vitamin A is 900 mcg (3000 IU), and for women – 700 mcg (2300 IU). Adolescents need about 600 micrograms of retinol (2000 IU), and children need 300-400 micrograms. Vitamin A doses are usually increased during pregnancy and breastfeeding.
Since vitamin A is able to accumulate in the tissues of the body, its regular use in excessive amounts leads to an overabundance and intoxication. The upper limit of the safe daily dose is 3000 micrograms for adults and 900 micrograms for children. The safe limit for single use is about 9000 mcg.
Vitamin A norms:
- For men – 900 mcg (3000 IU)
- For women – 700 mcg (2300 IU)
- For teenagers – 600 mcg (2000 IU)
Vitamin A in food
Foods contain various types of vitamin A – a carotenoid (beta-carotene) in plants, and a retinoid in animals. Since the level of absorption of plant beta-carotene is ten times lower, animal products are the best source of vitamin A.
1. Cod liver oil
Cod liver oil contains not only the maximum dose of vitamin A – one capsule is enough to cover the daily requirement – but also other fat-soluble vitamins, as well as omega-3 fatty acids. Ultimately, a similar composition is necessary for the normal functioning of the immune system.
2. Liver
The leader in the content of vitamin A is turkey liver – 900% of the norm of retinol per 100 g. Then follows beef and pork liver – 720% of the norm per 100 g, and chicken liver contains up to 370% of the norm of vitamin A. It is also important that the level of assimilation retinol from the liver is maximum.
3. Bell pepper
Sweet red and yellow bell peppers contain up to 2100 mcg of vitamin A per 100 g – or 230% of the recommended daily allowance. It also has a high amount of vitamin C. At the same time, green pepper contains much less vitamin A – only 20 mcg per 100 g.
4. Sweet potato
Strictly speaking, yam (sweet potato) is a distant relative of squash and carrots, not regular potatoes. There are different varieties of sweet potato, differing in the color of the pulp – white, yellow, and purple. A lot of vitamin A is found, first of all, in yellow sweet potato – 1000 mcg (110% of the norm) per 100 g.
5. Carrot
Vegetable vitamin A (carotene) owes its name to carrots (from the Latin carota) – 100 g of this product contains 830 mcg or 90% of the daily requirement. In fact, it is carrots that are the most affordable source of vitamin A in the daily diet.
6. Leafy vegetables
While green leafy vegetables (most notably spinach) contain vitamin A—on the order of 500 micrograms, or 50% of the DV—it’s important to remember that we’re talking about a 100g serving. therefore, it is important to monitor the amount of product used.
7. Dairy products
Vitamin A is found in dairy products. It is most abundant in butter (680 micrograms or 75% of the norm per 100 g) and soft cheese (265 micrograms or 30% of the norm). A slightly smaller amount of retinol is found in cottage cheese and in fat milk. However, a glass of milk is 100 micrograms of vitamin A or 9% of the norm.
8. Pumpkin
Like any other yellow-red vegetable, pumpkin contains a lot of retinol in the form of beta-carotene, which gives it its characteristic color. 100 g of pumpkin contains 430 micrograms of vitamin A – about 40% of the daily requirement. In addition, pumpkin is rich in soluble fiber.
9. Eggs
The benefits of chicken eggs are based not only on the high content of animal vitamin A, which has the maximum level of assimilation but also on the content of lecithin, another nutrient important for the work of substances. One medium egg covers about 10-15% of the daily requirement for vitamin A.
10. Melon
Melon is another good source of vitamin A. 100 g of melon contains up to 170 micrograms of beta-carotene – which is equivalent to 20% of the daily value. However, we recall that the level of absorption of beta-carotene is lower than the level of absorption of animal vitamin A – 1 μg of beta-carotene equates to 1/12 or even 1/24 μg of retinol from the liver of marine fish.
Deficiency symptoms
Since vitamin A is the first vitamin to be discovered, the symptoms of acute deficiency were initially studied. We are talking about loss of vision, acute disorders of the gastrointestinal tract, and even death. However, in the modern world, such a critical lack of vitamin A is quite rare.
Vitamin A deficiency negatively affects the thyroid and sex hormones, prevents the absorption of iron from food, and accelerates the development of iron deficiency anemia. Insufficient intake of retinol is dangerous for women – especially for pregnant women since the vitamin is responsible for the nutrition of the fetus.
Vitamin A deficiency symptoms:
- Chronic dry skin and mucous membranes
- Decreased eye adaptation time to darkness
- Hair deterioration (can lead to hair loss as well)
- A sharp drop in immunity
Hypervitaminosis
Retinoids, synthetic analogs of vitamin A, are found in many cosmetic products to treat skin or prolong its youth – ranging from anti-aging creams and sunburn lotions, to acne medications and even stretch mark creams.
Vitamin A in capsules, especially when used simultaneously with an anti-aging skin cream, can lead to an overabundance and intoxication. In addition, vitamin A in the form of supplements is incompatible with antibiotic treatment or anticoagulants.
Vitamin A is needed by the human body to maintain immunity and ensure the functioning of tissue cells. Most of this vitamin is found in cod liver, sweet red peppers, carrots, and sweet potatoes. To cover the daily requirement, it is enough to eat 100 g of carrots.