The medical name of vitamin A excess is "hypervitaminosis A". Hypervitaminosis A occurs when the maximum limit for liver stores of retinoids is
exceeded. The excess vitamin A enters the circulation causing systemic toxicity.
Vitamin A is used in the body for vision, immunity and bone and tissue growth and maintenance. Excessive Vitamin A use during pregnancy may increase
the risk of birth defects. Vitamin A overdose can cause symptoms such as orange skin, blurred vision and nausea. Vitamin A toxicity can cause more
severe symptoms such as growth retardation, hair loss and enlarged spleen and liver and even death.
Retinol and beta carotene both belong to the Vitamin A family. The body automatically removes excess beta carotene so it is impossible to overdose on
this type of Vitamin A.
Hypervitaminosis A can cause:
- Birth defects
- Liver problems
- Reduced bone mineral density that may result in osteoporosis
- Coarse bone growths
- Skin dryness/peeling
Although hypervitaminosis A can occur when very large amounts of liver are regularly consumed, most cases of Vitamin A toxicity result from an excess
intake of Vitamin A in supplements.
The Institute of Medicine has established Daily Tolerable Upper Levels (UL) of intake for vitamin A from supplements that apply to healthy populations.
The UL was established to help prevent the risk of vitamin A toxicity or overdose. The risk of adverse health effects increases at intakes greater than
the UL. You can easily check levels of Vitamin A for any type of food by looking into "Vitamins" tab on Food Details page (for example:
Fried Beef Liver
The UL does not apply to malnourished individuals receiving Vitamin A either periodically or through fortification programs as a means of preventing
deficiency. It also does not apply to individuals being treated with Vitamin A by medical doctors for diseases such as retinitis pigmentosa.