Vitamin A: Your Best Friend
2,879 viewsVitamin A is perhaps the most important vitamin. It is called retinol and is easily transformed into the human body in retinoic acid. It exists in two main ways: all-trans retinoic acid (ATRA, the most important) and 9-cis retinoic acid (9-cis RA). An obvious function of vitamin A is like a big compound of proteins (called Rhodopsin) in eyes that react to light and make vision possible. Most functions of this vitamin, however, is performed by its receptors, which are transcription factors of the nuclear receptor family. For these receptors, retinoic acid can affect almost every function in the human cell. Knowing this, it is easy to understand why the vitamin must be consumed in normal amounts. But more recent work shows that vitamin A acts as antioxidant (it combats free radicals that accelerate aging and are associated with some diseases). However, caution should be taken in using vitamin A, the excess is harmful. Scientific Name = Retinol or Axeroftol.
Consequences of the Lack of Vitamin A
The avitaminosis which is related to Vitamin A deficiency is xerophthalmia. One of the epithelium severely affected is the eye of the lining, leading to xerophthalmia. Xerophthalmia is the generic name given to various ocular signs and symptoms of hypovitaminosis A. The earliest clinical manifestation of xerophthalmia are night blindness, where the child can not look good adaptation in poorly lit; more pronounced manifestations of xerophthalmia, Bitot’s spots are usually located on the exposed part of the conjunctiva and xerosis; in later stages the cornea is also affected being the corneal xerosis, characterized by the loss of brightness and assuming an aspect granular corneal ulceration, ulceration can lead to progressive necrosis and destruction of the eyeball leading to irreversible blindness, which is called Keratomalacia.
Other complications related to vitamin A deficiency include poor vision at night (night-blindness), sensitivity to light (photophobia), reduction of smell and taste, dryness and infection in the skin and mucous membranes (xeroderma), stress, thickening of corneal injuries skin cancer and eye. Xerophthalmia is different from night-blindness, is being called the ‘night blindness’ and that, dry eyes, which promotes the increased friction between the eyelids and the eye, causing ulcerations in the epithelium of the eye.
The vitamin A deficiency also causes hyperplasia (uncontrolled multiplication of cells) and metaplasia (loss of cell shape), and the emergence of opportunistic diseases.
Frequent infections may indicate deficiency, since a lack of vitamin A reduces the body’s ability to defend itself from diseases.
Causes of the Lack of Vitamin A
- Lack of breastfeeding or early weaning: breast milk is rich in vitamin A and is the ideal food for children under two years old.
- Insufficient consumption of foods rich in vitamin A.
- Insufficient consumption of foods containing fat: the human body needs a quantity of dietary fat to keep several functions essential for its proper functioning. One is to allow the absorption of some fat soluble vitamins (vitamins A, D, E and K).
- Frequent infections: infections that affect children leads to a decrease in appetite: The child begins to eat less food may arise a deficiency of Vitamin A. Moreover, the infection causes the body’s need for vitamin A are higher, leading to reduced inventories in the body and triggering or worsening nutritional status.
Consequences of an Excess of Vitamin A
By ingesting excessive manifestations may be as dry skin, rough and scaly, cracking lips, follicular keratosis, bone and joint pain, headaches, dizziness and nausea, hair loss, muscle cramps, liver damage and stops growth. May also arise lack of appetite, edema, fatigue, irritability, and bleeding. Enlarged spleen and liver, abnormal liver function tests, reduction in cholesterol and HDL cholesterol may also occur. Great care should be given to products containing retinoic acid used in the treatment of acne.
The precursors of vitamin A have a significant influence on the amount of vitamin A that must be ingested. There are compounds related to vitamins that can be converted within the body into vitamin active (pro-vitamin). Some carotenoids are pro-vitamin A, the most important being the beta-carotene, followed by alpha-carotene. As the excess of vitamin A is stored in the body reaching cause toxic levels, they can use to carotenoids that can be consumed in doses considerably higher without an accumulation is harmful.
Consumption of beta-carotene of about 30 mg / day increases the likelihood of lung cancer and prostate. Smokers and people who have suffered exposure to asbestos should not consume supplements of beta-carotene.