Vitamin A is very important in organism and can be found in animals products. It performs many functions:
– necessary in the process of view- retinal is component of rhodopsin ( it’s photosensitive pigment located in retinal rods). Vitamin A regulates arising process of new cells, so to have good sight, we have to eat products rich in vitamin A,
– responsible for proper action of skin and mucous membrane preventing from infection,
– improves immunity- maintains efficiency of thymus; in thymus accelerates lymphocytes T. Vitamin A increases producing blood cells: granulocytes and leukocytes,
– takes part in lipids and hormones (especially thyroids hormones) conversion.
Pro-vitamins A- carotenoids
– mostly plants products,
– most important is beta-carotene,
– from 1 beta-carotene will arise 2 vitamins A,
– this conversion beta-carotene in vitamin A has place in intestine epithelium and in liver, also needs in process zinc.
Beta-carotene is natural antioxidant and prevents organism from free radicals. In deficient of beta-carotene free radicals will damage nucleus in cells and can cause heart disorders, cancers, cataract and fast agening. Risk these disorders decrease following vitamins: E and C and also one mineral- selenium.
Deficient of vitamin A:
– dry and swelling conjunctiva, dry cornea,
– inflammations of eyelids,
– disorders in regenerating visual purpure- rhodopsin and caused by this- night-blindnesses,
– vitamin A cooperates with Growth Hormone,
– dry and scaly skin,
– drying epithelium in respiratory system, digestive system and in urinary system,
– very sensitive on deficient are lungs, that’s why can occur often inflammations.
Where can we find vitamin A:
– full fat milk- 3,2%,
– egg yolks,
– sour cream,
Where can we find carotenoids:
– vegetables and fruits in yellow, red, green color, such as: carrots, pumpkin, green beans, apricots and peaches,
– also in dill, parsley, cabbage, lettuce, spinach and sorrel,
– moreover small amounts in milk, cheese.
Vitamin A is resistant during cooking, but another types of cooking processes, such as: frying, baking will cause loss till 25%.
Vitamin A is very photosensitive and keeping butter in improper conditions will cause loss till 70%.
Hypervitaminosis (excessive amounts of vitamin A in organism) is dangerous, because it will cumulate in liver, it’s not excreted and that’s why it’s toxic.
Toxic dose for adults is 15 000 ug and for kids 6 000 ug.
High intaking vitamin A by pregnant women (above 3 300 ug per day) can cause birth defects.
High intaking carotenoids isn’t toxic.