Hypervitaminosis
Acute hypervitaminosis A results from ingestion of very large amounts of the vitamin during a relatively short period of time.
The symptoms, which resolve after supplementation is stopped, include irritability, headache, vomiting, bone pain, weakness, blurred vision, and peeling of the skin.
Chronic hypervitaminosis A can result from high intakes of vitamin A over long period of time and/or in connection with liver or kidney disease.
Some of the signs of chronic hypervitaminosis A are dry skin, hair loss, weakness, headache, bone thickening, enlarged, liver and spleen, anemia, abnormal menstrual periods, stiffness and joint pain; most of these symptoms are reversible, but bone changes and liver damage may be permanent.
Vitamin A in very large doses is known to be teratogenic in many animals. Excessive intake of vitamin A has also been associated with human congenital abnormalities in some cases reports although a causal relationship has not been established.
High intakes should be avoided by pregnant women.
Levels of vitamin A intake associated with hypervitaminosis A varies according to the health and size of the person.
As little as 12,000 IU/day, given to small children for an extended period, has reportedly led to toxicity symptoms.
Hypervitaminosis A may result from acute ingestion of about 500,000 IU of vitamin A by an adult, or from a chronic daily intake of about 100,000 IU.
Hypervitaminosis
