What it does: This vitamin prevents night blindness, maintains the skin and cells that line the respiratory and gastrointestinal tracts, and helps to build teeth and bones. It is vital for normal reproduction, growth and development too. In addition, vitamin A is crucial to the immune system, including the plentiful supply of immune cells that line the airways and digestive tract and form an important line of defence against disease.
Major benefits: Vitamin A is perhaps best known for its ability to maintain vision, especially night vision, assisting the eye in adjusting from bright light to darkness. It can also alleviate such specific eye complaints as “dry eye”, in addition to its many other benefits. By boosting immunity, vitamin A greatly strengthens resistance to infections, including sore throats, colds, flu, and bronchitis.
It may also combat cold sores and shingles (mkanda wa jeshi-caused by a herpes virus), warts (a viral skin infection) eye infections and vaginal yeast infections-and perhaps even control allergies. The vitamin may help the immune system battle against breast and lung cancers and improve survival rates in those with leukemia. In addition, animal studies suggest it inhibits melanoma, a deadly form of skin cancer.
Another benefit for cancer patients is that vitamin A may enhance the effectiveness of chemotherapy (treatment of cancer using drugs). Vitamin A can also assist to improve and boost immunity in HIV/AIDS patients. Children with recurrent chest infections and diarrhoea are given Vitamin A to boost their immunity; the same applies to children with measles and who are malnourished.
Vitamin A was first used in the 1940s to treat skin disorders, including acne and psoriasis, but the doses were high and toxic. Scientists later developed safer vitamin A derivatives (notably retinoic acid). Now sold as prescription medicines, these include an acne and ant wrinkle cream. Lower doses of vitamin A can be used to treat a range of skin conditions, including acne, dry skin, eczema, rosacea and psoriasis.
Vitamin A also promotes the healing of skin wounds and can be applied to cuts, scrapes and burns. It may hasten recovery from sprains and strains. The therapeutic effects of vitamin A extend to the lining of the digestive tract, where it helps to treat inflammatory bowel disease and ulcers.
In addition, getting enough of this vitamin will speed recovery in people who have had a stroke. Women with heavy or prolonged menstrual periods are sometimes deficient in this vitamin, so supplements may be of value in treating this condition as well. Vitamin A deficiency can cause night blindness (even total blindness) and a greatly lowered resistance to infection. Milder cases of deficiency do occur, especially in the elderly, who often have vitamin-poor diets.
Infections such as pneumonia can deplete vitamin A stores. If you get too much of vitamin A: An overabundance of vitamin A can be a real problem. A single dose of 500 000 IU (international unit) may induce weakness and vomiting. And as little as 25 000 IU a day for six years has been reported to cause serious liver disease (cirrhosis). Signs of toxicity include dry, cracking skin and brittle nails, hair which falls out easily, bleeding gums, weight loss, irritability, fatigue and nausea.
In my clinical practice I came across two cases of Vitamin A toxicity or over dosage, one in a five months old baby with a history of being given cod liver oil (mafuta ya samaki) the child had recurrent convulsions (degedege). Over dosage of cod liver oil that contains vitamin A caused a condition known as pseudo tumour cerebri (collection of fluid in the brain) causing convulsions. The only treatment was to stop the administration of cod liver oil.
A second case was a five year old with a heart condition whose mother was told to give carrots as part of vitamin A. The child had consumed a lot of carrots and had his skin turned to deep yellow like that of Chinese or oriental person. That condition is known as caroteinemia. Stopping eating carrots was the only remedy to stop caroteinemia. The condition does not cause death. Guidelines for use: Take supplements with food, because a little fat in the diet aids absorption. Vitamin E and zinc help the body to use vitamin A, which in turn boosts absorption of iron from foods.
Vitamin A is richly represented in fish, egg yolks, butter, organ meats such as liver (85 g provide more than 9000 IU), and fortified milk. Dark green, yellow, orange and red fruits and vegetables have large amounts of beta-carotene and many other carotenoids, which the body makes into vitamin A on and as needed basis.
Caution: In a pregnant woman or who is intending to become pregnant, the expecting woman should not take more than 5000 IU of vitamin A daily: higher doses may cause birth defects. Practice effective birth control when taking doses higher than 5000 IU and for at least a month afterwards. Reminder: If you have a medical condition, talk to your doctor before taking supplements.
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