Vitamin A plays a vital role in maintaining healthy eyes. Vitamin A keeps our Vision Keen. Not only Eyes, Vitamin A helps in bone growth, maintaining immunity and also useful as Powerful Antiixidant, Vitamin A maintains a vigorous reproductive system of the body.
Vitamin A is a fat soluble vitamin. Actually, it is the name of a group of fat soluble retinoid, including Retinol, Retinoic acid, Retinyl Esters. Two forms of vitamin A are available in the human diet.
- Preformed Vitamin A (retinal and its esterified form, Retinyl ester)
- Provitamin A carotenoids
The most important provitamin A carotenoid is beta carotene. Other carotenoids are Alfa carotene and beta cryptoxanthin. The body converts these plant pigments into vitamin A. the active forms of vitamin A are retinol and retinoic acid.
Vitamin A Benefits :
- Vitamin A plays critical role in the formation of rhodopsin, the eye pigment responsible for sensing low light situations.
- Helps in forming and maintaining healthy skin, teeth, skeletal and soft tissue, and mucous membrane.
- Involved in immune function, reproduction, cellular communication.
- Vitamin A also supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, kidneys and other organs
Vitamin A sources:-
Vitamin A comes from animal sources such as
- Eggs
- Meat
- Fortified milk
- Cheese
- Cream
- Chicken Liver, Kidney, Cod
- Halibut fish oil
Beta carotene sources are
- Bright yellow and orange fruits such as pink grapefruit, apricots, cantaloupe,mangoes
- Vegetables- carrot, sweet potato, pumpkin
- Other sources are broccoli, spinach, dark green leafy vegetables.
The more intense the color of a fruit or vegetable, the higher the beta carotene content. Vegetable sources are fat and cholesterol free.
Vitamin A deficiency:-
Vitamin A deficiency is common in many developing countries. Vitamin A deficiency typically begins during infancy, when infants do not receive adequate supplies of colostrum or breast milk. Chronic diarrhea also leads to excessive loss of vitamin A in young children, and vitamin A deficiency increases the risk of diarrhea.
- The most common symptom of vitamin A deficiency in young children and pregnant women is Xerophthalmia.it is a medical condition in which the eye fails to produce tears. The conjunctiva becomes dry, thick and wrinkled. If untreated, it can lead to corneal ulceration and ultimately to blindness as a result of corneal damage
- Night blindness-one of the early sign of xerophthalmia.it is the difficulty for the eyes to adjust to dim light. Cannot see the images in low levels of illumination. Poor vision in the darkness but see normally when adequate light is present.
- Keratomalacia-vitamin A is required to maintain specialized epithelia such as in the cornea and conjunctiva. Lack of vitamin A leads to atrophic changes to normal mucosal surface, with loss of goblet cells, and replacement of normal epithelium by an inappropriate keratinized epithelium. Due to this cornea break down and liquefies resulting keratomalacia.The resulting cornea become totally opaque. This is one of the most common reason for blindness around the world
- Preterm infants with vitamin A deficiency have an increased risk of eye, chronic lung and gastrointestinal diseases.
- Bitot’s spots-collections of keratin in the conjunctiva
- Diminishes the ability to fight infections
- Decreased growth rate and slow bone development
- Most people with cystic fibrosis have pancreatic insufficiency, increasing their risk of vitamin A deficiency due to difficulty in absorbing fat. Vitamin A supplements can correct low serum beta carotene levels
- Vitamin A deficiency in the pregnant and lactating women leads to xerophthalmia and other effects are increased maternal and infant morbidity and mortality, increased anemia risk and slower infant growth and development.
- Vitamin A deficiencies tend to have low iron status, which can lead to anemia. It increases the severity and mortality risk of infections even before the onset of xerophthalmia
Treatment and prevention;
Taking vitamin A by mouth is effective for preventing and treating symptoms of vitamin A deficiency. Vitamin A deficiency can occur in people with protein deficiency, Diabetes, over active thyroid, liver disease, cystic fibrosis.
Vitamin A supplements may interact with some birth control pills, blood thinners, acne medicines, cancer treatment and many other drugs.
Vitamin A over dose:
Over dose of vitamin A is called as hypervitaminosis A. it refers to any number of a large amount of toxic effects from ingesting too much preformed vitamin A.This condition may be acute or chronic. Acute toxicity occurs after consumi9ng large amounts of vitamin A over a short period of time, typically within a few hours or days. Chronic toxicity occurs when large amounts of vitamin A build up in the body over a long period of time.
High intake of provitamin carotenoids such as beta-carotene, do not cause hypervitaminosis A as conversion to the active form of vitamin A is highly regulated.
Causes:
- Most people develop vitamin A toxicity by taking high dose dietary supplements or by taking more than the recommended amount over a long period of time
- It may also be caused by long term use of certain acne treatments that contain high doses of vitamin A.
Symptoms:
Long term use of large amounts of vitamin A might cause serious side effects including fatigue, irritability, mental changes, anorexia, stomach discomfort, nausea, vomiting, mild fever, excessive sweating, skin and hair changes, head ache.
In women who have passed menopause, taking too much vitamin A can increased risk of osteoporosis and hip fracture.
Over consumption of beta-carotene can cause carotenosis, in which the skin turns orange color.it is a reversible condition. The skin turns into normal color after you stop taking excessive consumption of beta carotene.
Other symptoms are abnormal softening of skull bone, blurred vision, bone pain and swelling, heart valve calcification, liver damage, poor weight gain in infants and children, higher sensitivity to sun light
Prevention:
- Don’t take more than recommended amount
- Carotene forms from dietary sources are not toxic.
- Pregnancy, liver disease, high alcohol consumption and smoking are indications for close monitoring and limitation of vitamin A administration.
Treatment:
- Stop taking high consumption of vitamin A
- Vitamin E may alleviate hypervitaminosis A
