A healthy human liver contains 575 international units (IU) of vitamin A per gram while a polar bear’s liver contains between 24,000 and 35,000 IU per gram. Compare that to the tolerable upper level of vitamin A intake for a healthy adult human: 10,000. Signs of toxicity generally occur when approximately 25,000 to 33,000 IU are consumed.
Illness severity depended on how much liver the explorers consumed, but symptoms typically included drowsiness, sluggishness, irritability, severe headache, bone pain, blurred vision and vomiting. While milder cases merely involved flaking around the mouth, some accounts reported cases of full-body skin loss. Even the thick skin on the bottoms of a patient’s feet could peel away, leaving the underlying flesh bloody and exposed. The worst cases ended in liver damage, hemorrhage, coma and death.
Seals developed a high tolerance for vitamin A and the ability to store large amounts of it as a defense mechanism, knowing that high levels were toxic to certain other animals, but they forgot the polar bears don’t give a fuck.