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Vitamin A is the first discovered vitamin of history. In 1913, it was considered to be growth factor, and in 1930, its chemical structure was described. It is mostly found in fatty acid ester form in foods. During digestion, it undergoes hydrolysis and absorbed freely. 90% of it is stored in liver, and the remaining 10% in other tissues. It acts as a hormone in the body. It is an essential vitamin for growth and development. Vitamin A can be in different forms. Preformed Vitamin A is mostly found in meat, fish and dairy products.
Provitamin A is found in vegetables and fruits. It is converted to Vitamin A by the body when necessary. Its overconsumption does not lead to a risk of toxicity. Being the precursor of Vitamin A, beta carotene is found in herbs. The active and circulating form of Vitamin A is called retinol. It is stored as retinyl palmitate in the body.
It affects various functions of the body. Its deficiency may result in many health problems like night blindness, dry skin, etc. Therefore, adequate intake is highly important. Following is the list of benefits of adequate vitamin intake:
It taken from fruits and vegetables reduces the risk of getting lung cancer. A diet rich in beta carotene is protective against oral and lung cancer. Studies have shown that carotene is also protective against colon cancer. It is proven that some types of Vitamin A are protective against prostate cancer.
According to a study, retinoic acid, a derivative of Vitamin A, lowered and balanced the blood sugar in diabetic mice.
It promotes tissue growth and development. Contributing to sebum production, it maintain the humidity level of the skin and hair. It promotes formation of health hair and skin cells.
It prevents vision problems like vision loss without any detectable reason and night blindness.
Being a type of Vitamin A, carotenoid is a strong antioxidant. It fights with free radicals which are the excessive electrons in the cells, and it hinders these radicals harming the cells and DNA.
Adequate Vitamin A intake is important for healthy teeth and gingiva. Its deficiency may lead to tooth, gingiva and tooth bone deformations.
It is responsible for the production and repair of the epithelial tissues like intestines and skin. Its deficiency may result in problems in the gastrointestinal system and kidneys. It protects the health of mouth, stomach, small intestine and urinary tract tissues, and protects the epithelial tissues from infections.
It takes on the task of protecting mucous membranes of mouth, nose, lungs and throat.
Adequate Vitamin A intake is only possible with balanced diet. In addition to vegetables and fruits that are rich in it, foods of animal origin should also be consumed in adequate amounts. Recommended daily amount is as following:
A diet that is not balanced for Vitamin A may result in its deficiency. In this case, the individual may experience many health problems, mainly night blindness. Premature infants, infants and children living in developing countries, breastfeeding and pregnant women in developing countries, and patients with cystic fibrosis are at risk.
Vitamin A deficiency may bring along many conditions such as unsatisfactory growth and development in children, weakened immune system, etc. Following is the list of the most important problems caused by Vitamin A deficiency:
It is necessary for reproduction both in men and women. In case of vitamin deficiency, infertility may be seen in women and men. One of the main reasons of recurrent abortions in women is VitaminA deficiency.
Children who cannot take adequate amounts of Vitamin A cannot grow expectedly. Shortness can be seen in children. Other than pudginess, developmental problems may also be seen.
The individuals may start to catch infections easier, mainly throat and chest infections. The main reason for this is the weakened immune system.
One of the functions of Vitamin A is to promote collagen production in the skin. In case of Vitamin A deficiency, the healing period of the wounds gets prolonged. For diabetes sores, usually oral and topical medications containing Vitamin A are prescribed.
In patients with severe Vitamin A deficiency, night blindness may be seen. With advancing deficiency, korneal ulcer injury may occur. This may result in vision loss, i.e., blindness.
Vitamin A is stored in liver. When it is over-consumed, it may result in fatty liver. Additionally, excessive and regular Vitamin A supplement use may trigger fatty liver.
Eye examination is usually used for the detection of Vitamin A deficiency. The amount of Vitamin A in the blood can be measured by blood test. Your doctor may also review your medical history. He/she may ask you question to diagnose night blindness.
Vitamin A deficiency can be treated using Vitamin A supplements. The amount of supplement may vary based on age and sex. Night blindness can be treated using vitamin supplements. However, vision loss caused by corneal injury cannot be treated using supplements.
Vitamin A medications can be in tablet and capsule form, as well as, in cream form for topical use. It derivatives are especially found in creams for pimple and acne treatment. Carovit and Avicap are the most commonly prescribed oral medications for the treatment of Vitamin A prescription.
Following is the list of foods rich in Vitamin A:
Known as A1, retinol is only found in foods of animal origin as liver, cheese, fatty fish, milk and butter. Cattle liver, liver sausage, lamb liver, salmon and mackerel, butter, cheese, caviar, trout and boiled egg are best retinol sources.
Carotenoids in herbs are converted to Vitamin A in our body. Consisting of beta carotene and alfa carotene, provitamin A is converted to Vitamins A2 and A3. Sweet potato, broccoli, carrot, turnip, spinach, pepper, other dark green-leafy vegetables are the other vegetables containing VitaminA.
Mango, grapefruit, watermelon, apricot, mandarin and nectarine are some fruits rich in VitaminA.
Orange colored vegetables and fruits are especially rich in carotenoid and beta-carotene. Natural VitaminA sources are orange colored vegetables, mainly carrot and pumpkin and orange colored fruits such as melon.
WARNING: Overconsumption of Vitamin A by pregnant women may cause fetal deformities. As ‘retinol’ is also found in anti-aging creams, pregnant women should avoid using retinol-containing creams. Beta carotene is not as dangerous as retinol. Vitamin A supplements carry the highest risk.
When preformed Vitamin A is over-consumed with diet or with supplement use, the individual may suffer from It elevation. Tolerable upper level of intake is based on the age. Exceeding the upper level results in toxic effects.
References: 1- Vitamin A, 2- Everything about vitamin A, 3- Foods contain Vitamin A