Fact: Polar Bear Livers are Poisonous

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While liver is often eaten, the vitamin A content of the liver of certain animals—including the polar bear, seal, walrus, moose, and husky—is highly hazardous. This danger has long been known to the Inuit and has been used by Europeans since at least 1597 when Gerrit de Veer wrote in his diary that, while taking refuge in the winter in Nova Zemlya, he and his men became severely ill after eating polar bear liver. The consumption of too much vitamin A can result in a condition known as hypervitaminosis A, with signs of acute toxicity including nausea and vomiting, headache, dizziness, blurred vision, and loss of muscular coordination.

source: wikipedia
the science: Rodahl, K. and T. Moore (1943). "The vitamin A content and toxicity of bear and seal liver". Biochemical Journal, vol. 37, pp. 166–168