Shark meat is high in protein and packed with certain nutrients, but the health risks generally outweigh the benefits. With an average mercury concentration of 0.979 ppm, shark ranks among the most mercury-contaminated seafood available, and the FDA classifies it as a “Choice to Avoid” due to its highest mercury levels. For most people, other fish deliver the same nutritional advantages without the toxic baggage.
Nutritional Profile of Shark Meat
On paper, shark looks like a solid protein source. A 100-gram serving of raw shark (about 3.5 ounces) contains roughly 130 calories, 21 grams of protein, and 36.5 micrograms of selenium, which is about two-thirds of your daily recommended intake. Shark is also a low-fat source of vitamins B6 and B12, both important for energy metabolism and nerve function.
Certain shark species also provide meaningful amounts of omega-3 fatty acids. Spiny dogfish, for instance, contains about 0.7 grams of EPA and 1.2 grams of DHA per 100 grams of edible tissue. That’s a generous amount, comparable to salmon. These omega-3s support heart health, reduce inflammation, and play a role in brain function. But here’s the problem: you can get equivalent or better omega-3 levels from salmon, sardines, or mackerel without the contamination concerns that come with shark.
Why Mercury Is the Central Problem
Sharks sit at the top of the ocean food chain. They eat smaller fish that have already absorbed mercury from the water, and that mercury accumulates in shark tissue over a lifetime. The result is striking: FDA monitoring data from 356 samples shows an average mercury level of 0.979 ppm in shark meat, with some individual samples reaching as high as 4.54 ppm. For comparison, shrimp averages around 0.009 ppm and salmon hovers near 0.022 ppm.
Not all sharks carry the same load. Mako shark is particularly problematic, averaging 1.83 ppm of mercury in a New Jersey study of 51 fish. Thresher shark came in lower at 0.41 ppm in that same research, though only one sample was tested. The variation matters if you’re choosing between species, but even the “lower” end of shark mercury levels is high relative to most seafood.
One detail that makes mako especially concerning: its selenium-to-mercury ratio falls below 1:1 (measured at 0.36). Selenium can partially offset mercury’s toxicity in the body, and most fish have more selenium than mercury. Mako is one of the few where mercury overwhelms the selenium, removing that natural buffer.
Risks Beyond Mercury
Mercury gets the most attention, but shark meat carries additional concerns. A study of 25 sharks from six species found that arsenic levels averaged 7.71 mg/kg in muscle tissue, more than twice the regulatory maximum set by many food safety organizations. Five of the six species tested exceeded safe limits for arsenic. Lead and cadmium levels, by contrast, fell within acceptable ranges.
Shark fins and cartilage contain a neurotoxin called BMAA, produced by cyanobacteria and linked to neurodegenerative diseases. Researchers detected BMAA in shark fins across all 10 species they surveyed, with concentrations ranging widely. In animal studies, primates fed BMAA for 140 days developed brain changes resembling those seen in Alzheimer’s and ALS patients. Whether the amounts found in shark products pose a direct risk to humans isn’t fully established, but the presence of a neurotoxin in nearly every sample tested is worth noting, particularly for anyone taking shark cartilage supplements.
There’s also the ammonia issue. Sharks retain urea in their blood and tissues as part of their biology. After the fish dies, that urea converts to ammonia during storage, giving shark meat a harsh smell and taste if it isn’t processed properly. Traditional preparation methods involve soaking the meat in water, sugar, or salt solutions to draw out the ammonia. When done well, this makes the meat safe and palatable. When done poorly, you’re eating a product with elevated ammonia levels.
Who Should Avoid Shark Entirely
The FDA places shark in its “Choices to Avoid” category for pregnant and breastfeeding women, people who may become pregnant, and young children. Methylmercury, the form of mercury found in fish, crosses the placenta and interferes with brain and neural development in fetuses and young children. The European Food Safety Authority echoes this guidance, noting that large predator fish like shark accumulate mercury over their lifespan precisely because they feed on smaller contaminated fish.
For adults outside these groups, occasional shark consumption is unlikely to cause acute harm. But “unlikely to cause acute harm” is a low bar for a food choice. Regular consumption builds mercury levels in your body over time, and mercury clears slowly, with a half-life of roughly 70 to 80 days in the bloodstream.
How Shark Compares to Safer Alternatives
The nutritional selling points of shark, high protein, omega-3s, selenium, and B vitamins, are all available from fish that carry a fraction of the contamination risk. Salmon provides comparable or higher omega-3 content with minimal mercury. Sardines are among the lowest-mercury fish available and are rich in both selenium and B12. Even canned light tuna, while not mercury-free, averages around 0.126 ppm, roughly one-eighth the level found in shark.
If you enjoy shark for its firm texture and mild flavor, swordfish and mahi-mahi offer a somewhat similar eating experience, though swordfish also carries elevated mercury (about 0.995 ppm on average). Mahi-mahi is a better swap, with mercury levels typically around 0.178 ppm and a similarly meaty texture that holds up well on the grill.
The bottom line is straightforward: shark meat delivers real nutrients, but every one of those nutrients is available from seafood that doesn’t come loaded with mercury, arsenic, and potential neurotoxins. For the occasional adventurous meal, a single serving is not dangerous for most healthy adults. As a regular part of your diet, it’s one of the least favorable seafood choices you can make.