Excess intake of beta-carotene (hypercarotenosis) results in staining of the skin a yellow-orange color but is otherwise benign. Skin changes are most marked on the palms and soles, while scleras remain white, clearly distinguishing hypercarotenosis from jaundice.
Excessive vitamin A (hypervitaminosis A), on the other hand, can be quite toxic. Chronic toxicity usually occurs after ingestion of daily doses of over 50,000 IU/day for more than 3 months. Early manifestations include dry, scaly skin, hair loss, mouth sores, painful hyperostosis, anorexia, and vomiting. More serious findings include hypercalcemia; increased intracranial pressure with papilledema, headaches, and decreased cognition; and hepatomegaly, which can progress to cirrhosis. Acute toxicity can result from ingestion of excessive doses of vitamin A via medications or supplements. Manifestations include nausea, vomiting, abdominal pain, headache, papilledema, and lethargy.
The diagnosis can be confirmed by elevations of serum vitamin A levels. The only treatment is withdrawal of vitamin A from the diet. Most symptoms and signs improve rapidly.
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et al. Fortification of staple foods with vitamin A for vitamin A deficiency. Cochrane Database Syst Rev. 2019;5:CD010068.