Alternative names: Retinol deficiency.
This disease is most often seen in the elderly and poor in the U.S. In the rest of the world where vitamin deficiencies are more common, it is one of the most common causes of blindness.
Vitamin A is essential for innumerable biological functions – night and color vision, wound healing, bone and tooth formation, healthy skin, normal growth, reproductive and adrenal function, cartilage development, mucous membranes/secretions and lactation. Further, it may also be a factor in preventing cancers. It is important to the immune function, and has been shown to have antiviral properties.
Vitamin A deficiency is usually due to poor diet. At highest risk are the elderly and the poor, and it is very common in parts of the world where poor nutrition is endemic. It also tends to occur in patients with problems absorbing nutrients from the intestine, or in those who abuse mineral laxatives.
The most common symptoms of vitamin A deficiency are night blindness and xerophthalmia (drying and inflammation of the conjunctiva of the eye). Night blindness (difficulty seeing at night or in dim light) may be the first symptom of Vitamin A Deficiency. Other symptoms include dry eye, loss of taste, poor wound healing, and the formation of small, white spots in the inner eyelids.
Blood tests are available to check vitamin A levels.
Eventually, vitamin A-deficient patients develop problems with the cornea (the clear part of the eye) and may even become blind. Low vitamin A has for some time been associated with increased infection rate.
Taste deficiency is reported by patients with vitamin A deficiency; vitamin A helps maintain a keen sense of taste and smell.
Night blindness is commonly caused by a deficiency in vitamin A. It is considered one of the first indicators of vitamin A deficiency.
Vitamin A deficiency has been reported in people with chronic conjunctivitis. It is unknown whether vitamin A supplementation can prevent conjunctivitis or help people who already have the condition. [Int J Vitam Nutr Res 1976;46: pp.454-7 {in German}]
Vitamin A is involved in steroid hormone synthesis and cell differentiation. It is important for healthy growth, normal reproduction and lactation.
See link between Female Infertility and Vitamin A Deficiency.
Retinoic acid (an analogue of vitamin A) is needed for the differentiation of basal cells into mucus epithelial cells. A deficiency results in keratinization of mucus membranes that line the respiratory tract, intestines, urinary tract and epithelium of the eye. This in turn decreases the protective barrier role played by these membranes, resulting in an increased number of infections and other pathologies.
Vitamin A deficiency reduces the ability of the cells lining the lungs to remove disease-causing microorganisms, increasing risk of pneumonia.
Carotene compounds called lycopenes, which are found in high amounts in tomatoes, have been shown to protect against prostate cancer. Several studies have shown that males consuming tomato sauce receive some protection against cancer.
A deficiency of protein or zinc can reduce the amount of vitamin A released from the liver.
90% of all dietary retinol is in the form retinyl palmitate which requires action by pancreatic enzymes before it can be absorbed.
A deficiency of protein or zinc can reduce the amount of vitamin A released from the liver.
A healthy diet will help prevent the complications of vitamin A deficiency. Foods rich in vitamin A include milk, cheese, liver, kidney, cod oil, carrots, sweet potatoes, broccoli, spinach, cantaloupe, pink grapefruit, and most leafy green vegetables.
One study found serum retinol levels (a measure of vitamin A levels) to be significantly lower in women with menorrhagia than in healthy controls. 92% of those with lower levels experienced either complete relief or significant improvement after 25,000 IU of vitamin A was taken twice per day for 15 days.
Analogues of vitamin A are known as retinoids. Numerous studies have shown that retinoid deficiency enhances the risk of cancer in humans. Retinoids are being used in humans to treat cancers (particularly skin, lung, bladder, cervical or breast) which involve epithelial tissues. Vitamin A can be used to both treat and prevent cancers and there have been a number of studies showing beta carotene's protective effects against cancer.
If detected early, treat with 30,000 IU of vitamin A daily for a week. In cases of advanced Vitamin A Deficiency, 20,000 IU of vitamin A per kg of body weight is given every day for at least 5 days. Treatment needs to be started as soon as possible. If it is delayed too long, problems may become permanent.
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