Hypervitaminosis from retinol

Vitamin A toxicity appears to occur only when the amount of vitamin A exceeds the binding capability of the retinol binding protein. Hypervitaminosis A can canse severe anemia and thrombocytopenia, resulting from retinol-dependent bone marrow cell growth inhibition (39). 

HypervitamininosisA. In high doses, retinol can be toxic. Acute poisoning is rare and dependent on the dosage form. Nausea and vomiting are the most common symptoms. Most rapidly absorbed are the "clear" emulsions (usually formulated with a Tween or other surfactant). Next in order are the standard emulsions, usually produced from fish liver oils. The most slowly absorbed are the dry tablet formulations or an oil solution in a capsule. Chronic hypervitaminosis is... 

If the rate of uptake of retinol from the intestine consistently exceeds the capacity of the liver to dispose of it, significant amounts of retinol, mainly in the form of retinyl palmitate, appear in the general circulation and may give rise to toxic effects. The effects of hypervitaminosis A are many and varied. They include increased intracranial pressure, severe headache, hyperirritability, vomiting, diarrhoea, bone decalcification and skin lesions. The condition can be fatal. It has in the past been caused by over-zealous administration of concentrated sources of the vitamin such as halibut liver oil. This may contain several hundred times as much vitamin A and 40 times as much vitamin D as cod liver oil. It has also occurred in people who have eaten polar bear or husky dog liver which contain massive amounts of vitamin A. 

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