Vitamin A, also known as retinol, is important to the health of many of the body's tissues, particularly the eyes. That is because vitamin A helps in the formation of the pigments in the retina, the light sensitive part of the eye. Vitamin A is also important for the health of other tissues including the teeth, the skeleton, and the skin. An overdose of vitamin can cause vitamin A poisoning, or hypervitaminosis A.
Sources of Vitamin A
Vitamin A poisoning usually occurs when someone takes large amount of this vitamin, either acutely or over a long period of time. Natural food sources of vitamin A include eggs, meats, dairy products, like cheese and cream, liver, and fish like cod. Fruits and vegetables are high in beta-carotene, which can be converted into vitamin A. Fruits and vegetables rich in beta-carotene include carrots, pumpkin, cantaloupe, broccoli and dark leafy greens. Also, vitamin A is found in nutritional supplements, either alone or in multivitamins.
Causes of Vitamin A Poisoning
Vitamin A toxicity can be acute and is usually due to accidental ingestion by children, according to the Merck Manuals Online Medical Library. Chronic toxicity occurs after taking mega doses of vitamin A for months. This can occur when taking large concentrations of vitamin A supplements, or if a person uses vitamin A formulations on their skin for the treatment of acne. If a person ingests large amounts of beta-carotene-containing foods, like carrots, for a long time, he can develop carotenemia, which turns their skin yellows, but he will not develop vitamin A toxicity.
Symptoms of Acute Poisoning
Acute poisoning with vitamin A can result in headaches, drowsiness, irritability, and nausea and vomiting. Abdominal pain is also common, as well as peeling of the skin. Acute poisoning also causes increased intracranial pressure, a condition in which the pressure inside the skull increase to dangerous levels, causing headaches, confusion, lethargy, and which, if untreated, can cause permanent brain damage.
Symptoms of Chronic Poisoning
The symptoms of chronic poisoning vary from those of acute poisoning. Early symptoms include loss of hair from the scalp and the eyebrows, dry and rough skin, dry eyes and dry , cracked lips. The bones become frail and predisposed to fractures. Children become irritable and can have hepatomegaly, or enlargement of the liver, and splenomegaly, or enlargement of the spleen. Pseudotumor cerebri, a condition that causes headaches and visual changes, can also occur
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