“You haven’t been eating anything weird, have you?” my doctor asked. “Like, really weird?” I was feeling crappy, and a routine panel of lab tests showed that my liver was sending out a mild distress signal. Now we were trying to figure out why.
I didn’t think I had been eating anything weird, but I asked for clarification anyway. You never know if your normal might be someone else’s weird. “You’re not eating polar bear livers, right?” she continued. I shook my head. I have never eaten a polar bear liver. I don’t even like regular cow livers. I once had to eat a piece of liver to be polite and it nearly gagged me.
But the doctor’s question intrigued me. Who is eating polar bear livers? And why would they make you sick? I dove into the deep end of the Internet to find out.
In 1596, a team of Dutch explorers set out to find a northern sea passage from the Atlantic to the Pacific. Just two months into the expedition, their ship became icebound near Novaya Zemlya, a Russian archipelago in the Arctic sea. So the men scavenged lumber, built a house, and hunkered down to pass the lengthy, frigid winter “in great cold, poverty, misery, and griefe,” according to the diary of Gerrit de Veer, an officer on the crew.
Novaya Zemlya was polar bear country, and “beare” encounters were frequent. In one unfortunate incident, a bear came “sodainly stealing out” and caught one of the men by the neck. When the other men attempted a rescue, the bear “fiercely and cruelly ran at them, and gat another of them out from the companie, which she tare in peeces,” de Veer writes. Not surprisingly, “all the rest ran away.”
But the bears caused other difficulties too. One fair day in May, while the team tried to build a new boat that would carry them off that godforsaken island, another bear appeared. The men hid in the house and shot her. And then they did something they would come to regret—they cooked her liver and ate it. The meat went down easy, but the men soon fell ill. Three of them became “exceeding sicke,” de Veer writes. “All their skins came of from the foote to the head.” Improbably, these skinless men recovered, “for the which we gave God heartie thankes.”
Why the men became “exceeding sicke” didn’t become clear until the 1940s. A team of researchers tested a few livers collected from polar bears in Greenland and discovered that they’re chock full of vitamin A, a fat-soluble vitamin that is stored primarily in the liver. One liver from a two-year-old female bear contained 18,000 international units of vitamin A per gram. The US daily recommended allowance of vitamin A for adults is between 2,300 and 4,300 international units.
Vitamin A plays a critical role in eye health, and helps bolster the immune system. But too much—a condition called hypervitaminosis A—can cause toxic effects including nausea, headache, fatigue, dizziness, and the telltale loss of skin that de Veer described.
And it’s not just polar bears. Other Arctic animals such as arctic foxes, bearded seals, and glaucous gulls have similarly toxic livers. And so do some fish. The literature contains case reports of vitamin A poisoning from the livers of ocean perch, grouper, and several tropical fish.
Why some animals have toxic livers and others do not isn’t entirely clear. One team of researchers posits that the Arctic’s top predators have evolved a greater capacity to store vitamin A to deal with a vitamin A-rich diet. But I couldn’t find a good explanation for why their diet would be any richer in vitamin A than the diet of other top predators around the globe.
Whatever the reason, the message seems clear: Stay away from polar bear livers. Some might assume that de Veer’s gripping account of his party’s liver-induced illness would serve as a cautionary tale to future Arctic explorers. But not everyone heeded the warning. American explorer and surgeon Elisha Kane considered the rumors about polar bear liver being poisonous “vulgar prejudice.” During his visit to the Arctic in the 1950s, Kane “ate of it freely myself and succeeded in making it a favorite dish with the mess,” he wrote. That plan sometimes backfired. After eating a cub’s liver, Kane developed vertigo and diarrhea. In search of reproducible results, Kane “repeated the experiment several times afterward, and sometimes, but not always, with the same result.” The polar bear liver “may sometimes be more savory than safe,” he concluded.
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Interesting article. How are you feeling now? Did the doctor figure out what was making you feel crappy?
Very interesting! Googling into it, I find that it’s really complex. This source discusses regional variations in fish liver Vit A, and points out that marine fish have a different form of Vit A than freshwater fish. It also discusses a less-toxic storage form of the vitamin in whale liver.
Thanks for bringing up such an interesting topic.