Vitamin A is very important for the normal functioning of the human body. It helps the immune system fight viruses and bacteria, regulates the hormonal system, makes the skin smooth and elastic, and maintains youth and health. The need for vitamin A is provided by foods rich in it.
Vitamin A, or retinol, is a complex organic compound that is soluble in fats. It is of great importance for vision, the mucous membrane of the respiratory tract, gastrointestinal tract, and the reproductive system. With a lack of vitamin A, iodine deficiency progresses, stones are formed in the kidneys and bladder, pneumonia and various catarrhal conditions occur. Therefore, it is very important to include foods rich in vitamin A in the diet.
The peculiarity of vitamin A is that it is found only in animal products. In particular, in fish oil its content is 19 mg per 100 g of product (mg%), in beef liver - 8 mg%, in cod and pork liver - 4-5 mg%, up to 1 mg% - in granular caviar, 0, 6 mg% in butter, 0.4 mg% - in eggs, 0.3 mg% - in sour cream, 0.2 mg% - in cheese. Vitamin A is also present in milk, fermented milk products, meat and fish, but in small quantities.
However, vitamin A can also be obtained from plant foods. Many vegetables and fruits contain a special pigment - carotene, or provitamin A, which, when ingested, is synthesized in the liver into active retinol. Beta-carotene has the greatest ability to form vitamin A. However, the effectiveness of beta-carotene is 6 times lower than that of vitamin A. Other carotenes are even less active - 12 times.
Among the most important sources of provitamin A, red carrots are in the lead, the content of beta-carotene in which reaches 9 mg%. In sorrel, 8 mg% of the substance is found, in parsley - 6 mg%, in green onions and red peppers - 2 mg%, 1.5 mg% each in apricots and pumpkin, in tomatoes - 1 mg%. The carotene content depends to a large extent on the color of vegetables and fruits: there are more reds and yellows than greens.
Vitamin A is relatively resistant to high temperatures: during heat treatment, its losses do not exceed 40%, while beta-carotene is lost no more than 20%. Retinol tends to break down in acidic foods, so it is advisable to limit the addition of acids (acetic, citric) to food. Since vitamin A is a fat-soluble vitamin, it is absorbed best in the presence of fats, especially vegetable oil.
The daily requirement for vitamin A is 1-1.5 mg. With a normal diet, it is adequately provided by animal and plant products. In addition, vitamin A tends to accumulate in the liver. However, in case of its obvious insufficiency (decreased visual acuity, impaired growth, frequent infections and colds, etc.), it is advisable to adjust the diet and, if necessary, take vitamin preparations as prescribed by the doctor.
