Vitamin A, or Retinol, is one fat soluble vitamin, fat soluble. Can be accumulated in the liverit is therefore not necessary to take it regularly, through food.
The body stores it and releases it in small doses when needed.
The liver can store vitamin A in esterified form with long-chain fatty acids such as palmitic acid for several months. It contains up to 80% of the body’s retinol.
The known forms of vitamin A there are three, distinguished according to the oxidation state of the terminal functional group. They originate from a vegetable provitamin, beta-carotene and are:
- Retinol
- Retinal
- Retinoic Acid
Role of vitamin A
AND essential for our vision since together with its precursors, carotenoids, it is part of the components of rhodopsin, the substance present on the retina which gives the eye sensitivity to light.
It keeps skin, hair and mucous membranes healthy, helps keep fit, protects against lung infections.
has a antioxidant role and, especially beta-carotene, could carry out a preventive action against the attack of free radicals.
Ensures control of cell proliferation and differentiation, formation and shaping of the embryo, organogenesis, immune function and the epithelial barrier.
Vitamin A is also important for bone development and for their strengthening over time, for the growth of teeth and stands out for its ability to provide an immune response to our body.
Vitamin A also has anticancer capabilities.
Vitamin A deficiency
The main symptoms of vitamin A deficiency are: brittle nails, cirrhosis of the liver, diarrhoea, rough, dry or prematurely aged skin, frequent fatigue, absence of tear secretion, loss of smell, loss of appetite, obstruction of the bile ducts, ulcerative colitis, adverse effects on the hair such as hair changes of the sebaceous glands, dandruff formation, dry hair, thickening of the scalp.
Its deficiency can also slow down the thyroid and cause autoimmunity. In this situation of deficiency, it can cause various problems: it can reduce the absorption of thyroid iodine and its incorporation into Thyroglobulin, which could increase the size of the thyroid gland, alter the production of TSH and, consequently, also the levels of thyroid hormones.
Although all tissues are affected by vitamin A deficiency, the eyes are the ones most interested. The lack of vitamin A causes defective epithelialization in the cornea and keratomalacia, a pathological state that leads to the weakening and opacification of the cornea.
A lack of vitamin A, or retinol, can lead to blindness over time. In infants and children, Xerophthalmia, dry eyes, is an early symptom of vitamin A deficiency.
In adults, on the other hand, a sign of vitamin A deficiency is night blindness, hemeralopia, a defect of adaptation to the dark. And again, in general, the lack of vitamin A can also create difficulties in the process of growth and development of the organism and can cause an excessive sensitivity to infections.
It may also involve, in case of pregnant womento fetal malformations.
Vitamin A excess
An excess of vitamin A, accumulated in the liver, can create Hypervitaminosis Ais toxic and can cause liver and spleen problems.
It is practically impossible to take an excess of vitamin A with food, in fact, the accumulation of vitamin A in the liver always derives from the excessive intake of drugs or food supplements.
I hypervitaminosis A symptoms are pain and bone fragility, possible dermatitis, nausea, diarrhea and abnormal development of the fetus so be careful during pregnancy.
The maximum daily intake is 1200 mcg.
Where is vitamin A found?
And natural vitamin A supplement it is cod liver oil. In foods of animal origin we find it in two forms, vitamin A1 (or retinol) and vitamin A2 (dehydro-3-retinol) and they are particularly abundant in eggs, fishery products (herring, anchovies, mackerel, oysters), meat (for example in veal liver we find a good quantity) and in dairy products.
In plants, however, it is present in the form of carotene which, within the body, is enzymatically converted into Vitamin A and it is for this reason that carotene is also called “provitamin A”.
The carotene with the greatest vitamin activity is β-carotene which however has a lower vitamin activity than that of retinol: in fact 6 micrograms of β-carotene are equivalent to 1 microgram of retinol.
We mostly find it in fresh vegetables yellow, dark green or red and even orange in color such as spinach, carrots, lettuce, apricots, watermelon, berries, asparagus, tomatoes, sweet potatoes, pumpkin, chicory, endive , asparagus, Brussels sprouts.
Vitamin A is absorbed from the intestineand being a fat-soluble micronutrient it should be accompanied by fatty foods, such as extra virgin olive oil and also vitamin E. It is instead reduced if the vitamin is taken together with alcohol, antacids, smoking and cholestyramine.
Since vitamin A is sensitive to heat, it is always better to consume i raw foods or after having subjected them to a short cooking so as not to alter its characteristics.
Per fill up on vitamin A try eating a salad for lunch made up of carrots, Belgian endive, lettuce, red fruits, a handful of raisins and walnuts, anchovies, extra virgin olive oil, salt and a pinch of pepper!