Vitamin for the wellbeing of the tissues, of the eyes and of the immune system, should be introduced with the diet.
Vitamin A is a type of fat-soluble vitamin, this means that it is soluble in fats. Unlike water-soluble vitamins, such as vitamin C, it is stored in the liver and is used by the body for the growth and development of tissues and bones. Moreover, this vitamin regulates the functioning of eyes and retina, protects the health of skin, in fact it helps to fight acne and pimples, the health of hair and tissues of the body, such as the mucous membranes of the bronchi, of the intestine, of the bladder and of the inside of the ear, maintaining their integrity and functionality. Vitamin A also supports the immune system and strengthens the body's defenses against infections (Gilbert, Community Eye health, 2013). A vitamin A deficiency, which could occur with vision problems in low light conditions, less resistance to infections and dry, wrinkled and dull skin, is however rare because this vitamin is stored in the liver and used when it is needed. For the same reason supplements with vitamin A should be used carefully and always under medical supervision, because vitamin A accumulates and its excess may be toxic. So it is better to use just natural sources such as foods. In particular, it is possible to find vitamin A in the form of retinol in some foods of animal origin such as liver, whole milk, eggs, offal, cheese, butter and fatty fish. In addition to this, vitamin A can be found in the form of provitamin A, that is represented by substances, the carotenes, which are then converted into vitamin A by the body. Among the carotenes the main is the beta-carotene, that you can find in very high quantity in dandelion, fresh carrots and parsley leaves (> 5000 microgram / 100g). But we also find beta-carotenes in fennel, in fresh spinach, common cornsalad, broccoli, pumpkin, apricot, melon and chicory (1000-5000 microgram / 100g), tomato, lettuce (500-1000 microgram / 100g) and butter, cow's milk, sunflower oil and yogurt with 3,5% fat (less than 500 microgram / 100g). However, vitamin A is sensitive to heat. Therefore, to preserve its characteristics at best, the vegetables that contain vitamin A should be eaten raw or cooked only briefly. Finally, taking vitamin A with a fat, such as extra virgin olive oil, increases its absorption (Gilbert, Community Eye health, 2013).