A complete and balanced diet plays an important role in human health. Even in ancient times, people noticed that the use of certain foods significantly improves well-being, improves performance and has a beneficial effect on all processes in the body.
Among other biologically active substances, vitamin A occupies a special position. Under this term is a group of compounds similar in chemical structure and effect on the human body. It includes retinol, retinoids and carotenoids (provitamins).
From the article you will learn about which foods contain vitamin A, its concentration and bioavailability. Clinical manifestations of hyper- and hypovitaminosis, a personâ€™s daily need for retinoids will also be examined.
The benefits and importance of retinol
Vitamin A is an essential element in many chemical reactions that occur in the body. A deficiency of this substance is fraught with a violation of metabolic processes, which can lead to the malfunction of many organs and systems.
The most important functions of retinol:
- regulates the amount of proteins and steroid hormones;
- promotes maturation of germ cells;
- boosts immunity;
- participates in the formation of the musculoskeletal system;
- improves the condition of the skin, hair and nails;
- acts as an antioxidant, combating excess free radicals;
- necessary for harmonious intrauterine development;
- regulates twilight vision;
- eliminates dry skin and mucous membranes.
Vitamin A and fatty acids are essential components for the synthesis of sex hormones.
Steroids are involved in many processes, including the synthesis of gametes. Therefore, with a deficiency of retinol, violations of sexual and reproductive functions are possible.
Also, all substances from the retinoid group have a stimulating effect on the immune system. At the same time, resistance to bacterial and viral infections is growing.
Separately, it is worth paying attention to the antioxidant effect of this substance. It binds free radicals that have a damaging effect on body cells. This property enhances antitumor immunity, preventing cancer.
You need to know that high doses of any antioxidants have the opposite effect – the processes of cell damage are amplified, leading to its death. That is why it is important to adhere to the physiological norm of vitamin intake.
Vitamin A has a beneficial effect on the skin and its appendages. It prevents dry skin and mucous membranes, accelerates reparative processes. Retinol also helps to accelerate the growth of hair and nails, making them more durable and healthy.
The benefits of vitamin A have been proven for a growing body. He is involved in the formation of all organs and systems, including bone and endocrine.
Retinol is essential for maintaining eye health. It prevents the occurrence of dryness of the cornea and the development of keratoconjunctivitis. Also included in the visual pigment is rhodopsin, which is found in rods and cones. These are neurosensory cells located in the retina. They cause twilight vision.
Human Health Value
Retinol is an essential component in the nutrition of every person. A sufficient amount of vitamin increases the body’s resistance to adverse factors, prevents a decrease in immunity and contributes to a quick recovery.
Vitamin A is especially useful for pregnant women. It helps the body adapt to changes, and also takes part in the laying of fetal organs. That is why expectant mothers should include in their diet oil, fruits, vegetables, fish and other foods rich in this vitamin.
Doses of the vitamin depend on a number of factors:
- anthropometric parameters;
- baseline vitamin level;
- the presence of an additional need (heavy physical labor, pregnancy and lactation, acute and chronic diseases).
In the normal state of the gastrointestinal tract and the absence of chronic deficiency, a person can receive the necessary amount of retinol with food.
Vitamin A is found in plant and animal products. Therefore, getting the required amount of vitamin from the diet is quite realistic. However, in case of malabsorption of nutrients, with total vitamin deficiency or increased need, the use of food additives will be rational.
|Needs groups||Daily dose, mcg|
|Up to 6 months||600|
|7 – 12 months||600|
|Up to 3 years||600|
|4 – 8 years||900|
|9 – 13 years old||1700|
|Men||2800 – 3000|
|Women from 14 years old||2800|
How is the deficit manifested
Vitamin A hypovitaminosis is a serious pathological condition. Most often it develops over the years, for a long time without letting itself be known.
The main causes of retinol deficiency:
- alimentary – often vitamin deficiency is caused by an inadequate diet;
- pregnancy and lactation;
- growth and puberty;
- violation of digestion and absorption in the intestine;
- severe debilitating diseases, including cancer.
Recognizing hypo- or vitamin deficiency is extremely difficult. Symptoms appear, as a rule, with severe deficiency. General condition may not be violated. Such patients rarely complain and consult a doctor. They most often associate their condition with other causes.
Vitamin A deficiency has the following symptoms:
- impaired twilight vision;
- xerophthalmia (hypertrophic and degenerative processes in the cornea);
- dry skin, jams and cracks;
- premature appearance of wrinkles;
- fragility of nails;
- hair loss;
- decreased sense of smell due to dry nasal mucosa;
- frequent inflammatory diseases of the respiratory system due to a violation of the barrier function of the bronchial mucosa;
- violation of hormonal regulation, infertility.
Important! Even vitamin deficiency (an extreme degree of vitamin deficiency) can be asymptomatic for a long time.
Vitamin A overdose
It is extremely difficult to get hypervitaminosis by consuming large amounts of vitamin A with food. To do this, eat 3 kg of beef liver at a time. In general, acute conditions develop with improper dosage of medications. The clinical picture of severe poisoning is developing.
Chronic hypervitaminosis is often the result of taking tablet forms and a large number of products containing retinol.
Symptoms of an overdose of vitamin A:
- emotional lability;
- impaired consciousness;
In such cases, urgent medical advice and detoxification measures are necessary.
Vitamin Content in Food
Sources of vitamin A are divided into plant and animal. The former contain fat-soluble carotenoids, so they are recommended to be used in combination with oils.
Of the plant foods, carotene is most found in carrots. Also, bell peppers, apricots, peaches, oranges, pumpkin, avocado and parsley are rich in this vitamin. Many types of retinoids are destroyed by high temperatures. Therefore, it is preferable to eat vegetables and fruits in raw or dried form.
Products of animal origin with a high content of vitamin A include beef liver, eggs, fish oil, goat milk. In addition to retinol, they are rich in B vitamins, various macro- and microelements.
Table of main products with vitamin A
|Product name||Content per 100 grams of product|
|Fish fat||25000 mcg|
|Beef liver||8367 mcg|
|Dried apricots||583 mcg|
|Chicken egg||260 mcg|
|Bell pepper||250 mcg|
|Goat’s milk||57 mcg|
In the presence of hypo- or vitamin deficiency, the calculation of the daily dose will help to correct the lack of vitamin.
It should be borne in mind that plant foods contain carotenoids that are not completely absorbed and metabolized. Therefore, their dose may be increased.
Vitamin A in Carrots
Carrots are an indispensable product in the human diet. It contains a large amount of fiber and vitamins of groups B, PP, K, E and C. In addition, it occupies one of the leading positions in the content of beta-carotene. Once in the body, it undergoes metabolism and turns into retinol.
Unlike other products containing vitamin A, carrots have a low calorie content (about 35 kcal per 100 grams) and a low glycemic index. It is an indispensable source of carotene for people with diabetes or a low-carb diet.
In traditional medicine, not only fruits are used, but also carrot seeds, which also contain vitamin A. Infusions and decoctions are prepared from seeds, which favorably affect the functioning of the kidneys, liver and biliary tract.
Important! Beta-carotene is a fat-soluble vitamin, so you should eat carrots with a little oil.
Vitamin A Fruit
Fruits also relate to foods high in vitamin A. It is found in large quantities in apricots, peaches, mangoes, oranges and watermelons. Dried fruits such as dried apricots and papaya are also recommended. In them, the content of this substance is higher than in fresh ones. In addition to retinol, fruits are rich in vitamins of groups B, C, E.
It must be remembered that many substances from the vitamin A group are not sufficiently absorbed by the body due to the peculiarities of the chemical structure. Therefore, retinol contained in plant foods cannot be the only source of this vitamin.
Vitamin A and fish oil
Most animal products are rich in vitamin A. In addition, the form in which it is contained allows for higher bioavailability (the content of the substance in the blood) than plant analogues. Animal sources of retinol include eggs, beef liver, butter, cheese, milk, and seafood.
A special place is occupied by fish oil. This is a kind of concentrate not only retinol, but also cholecalciferol and omega-3 fatty acids. In this combination, each component of the mixture potentiates the effect of the other, leading to a more pronounced therapeutic effect.
Especially fish oil is useful for pregnant women and women of childbearing age. The components contained in this product favorably affect the condition of the skin and hair, as well as the synthesis of sex hormones.