You can eat shark liver, but it comes with serious risks that make it a poor choice compared to other foods. The biggest danger is vitamin A toxicity: shark liver contains extraordinarily high concentrations of vitamin A, and eating even a moderate portion can push you well past safe limits. Some shark species also carry toxins in their liver that require extensive processing to neutralize.
Why Shark Liver Is Dangerous to Eat
The liver is where sharks store massive amounts of fat-soluble vitamins, particularly vitamin A. Commercial shark liver oil has been measured at 4,000 to over 15,000 international units (IU) of vitamin A per gram. For context, the tolerable upper intake for an adult is 10,000 IU per day. A single ounce of high-potency shark liver could contain over 400,000 IU, enough to cause acute poisoning.
Acute vitamin A toxicity causes nausea, headache, blurred vision, and skin reactions including flushing, blister formation, and widespread peeling. In one documented case, a 63-year-old man ate roughly two fist-sized portions of cooked fish liver (300 to 400 grams) and developed fluid-filled blisters across his body along with generalized skin peeling. These symptoms can appear within hours of a single high-dose meal. Repeated exposure at lower levels can cause chronic toxicity, leading to liver damage, joint pain, and increased pressure inside the skull.
The liver also accounts for up to 25% of a shark’s total body weight, and its primary component is squalene, a lipid that can make up as much as 90% of the oil in deep-sea species. While squalene itself isn’t toxic, it serves as a vehicle for concentrated fat-soluble vitamins and any environmental contaminants the shark has accumulated.
Mercury and Heavy Metal Concerns
Sharks are apex predators, and their tissues accumulate mercury through a process called bioaccumulation. Muscle tissue in sharks caught off Florida’s coast contained mercury levels ranging from 0.19 to 4.52 mg/kg (parts per million). The FDA action level for mercury in fish is 1.0 ppm, meaning many shark species already exceed safe limits in their muscle alone. Blacktip sharks averaged 2.65 ppm, and great hammerheads averaged 1.65 ppm.
The liver, as a detoxification organ, processes and stores contaminants differently than muscle tissue. Interestingly, processed shark liver oil supplements tested on the Polish market showed low mercury levels (averaging 0.065 µg/kg), well below regulatory limits. But those supplements undergo industrial refinement. Eating whole, unprocessed shark liver is a very different story from taking a distilled oil capsule.
The Greenland Shark Problem
Certain species pose an additional risk beyond vitamins and metals. The Greenland shark is outright toxic when fresh. Its flesh and organs contain high concentrations of trimethylamine oxide (TMAO), which gut bacteria convert into trimethylamine (TMA) during digestion. TMA poisoning affects the nervous system and muscles, causing symptoms in both humans and dogs.
Icelanders have eaten Greenland shark for centuries, but only after an elaborate curing process. The traditional method involves burying the gutted shark in gravelly sand, pressing it with heavy stones for six to twelve weeks to drain fluids, then hanging the meat to dry for several additional months. This extended fermentation breaks down the toxic compounds enough to make the meat safe. The result, called hákarl, is famously pungent. Visitors have described it as tasting like “a jellied cube of ammonia.” The key point is that this species requires months of processing before it can be consumed at all.
Shark Liver Oil Supplements
Most people who consume shark liver today do so in supplement form rather than eating the organ directly. Shark liver oil is marketed as a source of alkylglycerols and squalene, compounds that some manufacturers claim support immune function. These supplements go through extraction, filtering, and standardization processes that remove or reduce contaminants and control the vitamin A dose per capsule.
Testing of commercial shark liver oil supplements has confirmed that mercury levels remain well within safety standards. However, “safe” in supplement form doesn’t mean unlimited. Overconsumption of any fat-soluble vitamin supplement can still cause toxicity, and the health claims around shark liver oil remain largely unproven in rigorous clinical trials.
Conservation Impact
There’s also an ethical dimension worth knowing about. Sharks and rays are the second most threatened class of vertebrates on Earth, with roughly 37.5% of species at elevated extinction risk. Oceanic shark populations declined over 70% between 1970 and 2018 while fishing pressure increased eighteen-fold. International demand for shark products, including fins, meat, liver oil, and skin, is a primary driver of these declines.
In response, 44 shark species have been listed under the Convention on International Trade in Endangered Species (CITES) since 2003, with most listings occurring after 2013. Five of those species are on Appendix I, which bans international commercial trade entirely. The remaining 39 are on Appendix II, requiring countries to prove that trade won’t harm wild populations before allowing exports. Three of the main species historically targeted for liver oil, the deep-sea shark, the dogfish, and the basking shark, have all faced significant population pressure from harvesting.
The Bottom Line on Eating It
Shark liver is technically edible in the sense that it won’t kill you in small amounts from most species. But the vitamin A concentrations are high enough that a single generous serving can cause acute poisoning with painful, dramatic symptoms. Certain species like the Greenland shark require months of specialized processing before any part of the animal is safe. And the ecological cost of shark harvesting makes it difficult to justify as a food source when safer, more sustainable alternatives exist. If you’re interested in the compounds found in shark liver, refined supplements offer a controlled dose without the risks of eating the raw organ.