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.
I actually heard about this from a YouTube channel referencing the diary of Gerrit de Veer from 1597 where he recounted his expeditions’ encounter with eating polar bear liver and nearly dying from it in 1596.
I can’t find the actual diary entry, but I think it’s behind a pay wall on the Wikipedia link as a reference.
The story the YouTuber told was presumably in the diary. He said their ship got stuck in ice and they used wood from the ship to make a cabin. Sometime later, they had a run-in with a polar bear and ended up shooting it from inside the cabin. Sometime after that, they had a group meal consuming the polar bear liver and everybody’s skin started falling off.
https://en.m.wikipedia.org/wiki/Gerrit_de_Veer