Understanding Mercury in Seafood
Mercury is a naturally occurring element, but human activities like coal burning can release it into the environment. Once in the water, microorganisms convert it into methylmercury, which is a potent neurotoxin. Fish then absorb the methylmercury as they feed. This process of bioaccumulation means that larger, older, and more predatory fish at the top of the food chain will have higher concentrations of mercury in their bodies than smaller fish. For this reason, selecting sushi made with fish from the bottom of the food chain is key to minimizing your mercury intake. While nearly all fish have trace amounts, the levels vary significantly.
The Lowest Mercury Sushi Options
To enjoy sushi while keeping mercury levels in check, consider these excellent low-mercury choices. These options include smaller fish and shellfish that accumulate significantly less mercury.
- Salmon (Sake): Wild and farmed salmon are both considered low in mercury, with some studies even suggesting farmed salmon may be lower due to controlled environments and faster growth. Its rich omega-3 content makes it a healthy choice.
- Shrimp (Ebi): These bottom feeders consistently rank among the seafood with the absolute lowest mercury content.
- Eel (Unagi or Anago): Both freshwater (unagi) and saltwater (anago) eels are good low-mercury options for sushi.
- Scallops (Hotate): Scallops are another shellfish known for their extremely low levels of mercury.
- Crab (Kani): Imitation crab, often made from pollock, is a very low-mercury choice, as is real crab meat.
- Pollock: Often used in imitation crab or as a standalone ingredient, pollock is a very low-mercury fish.
- Sardines (Iwashi): This small, oily fish is not only low in mercury but also packed with omega-3s.
- Cod: Often served cooked in rolls, cod is a great low-mercury fish.
High Mercury Sushi to Limit or Avoid
To balance your intake, it is important to be aware of the fish types that have higher mercury concentrations. These are typically larger, more predatory fish that have lived longer.
- Tuna (Maguro, Toro, Tekka): This is one of the most common high-mercury risks in sushi. Bigeye (maguro), bluefin (toro), and albacore tunas have the highest levels. Skipjack (light tuna) is a lower mercury variety, but it's not always used for sushi.
- Swordfish (Kajiki): This predatory fish is notorious for its high mercury content and should be avoided or consumed very rarely.
- Mackerel (Saba): Some varieties of mackerel, particularly king mackerel, are high in mercury. Atlantic mackerel is a lower mercury option.
- Marlin: Similar to swordfish, marlin is a large predator with high mercury levels.
Comparison Table: Mercury Levels in Common Sushi Ingredients
| Sushi Ingredient | Average Mercury (ppm) | Mercury Level | Best for Frequent Consumption? |
|---|---|---|---|
| Shrimp | 0.001 | Very Low | Yes |
| Scallops | 0.003 | Very Low | Yes |
| Salmon | 0.022 | Low | Yes |
| Pollock | 0.031 | Low | Yes |
| Atlantic Mackerel | 0.050 | Low | Yes |
| Cod | 0.111 | Moderate | Moderate (or check local advisories) |
| Yellowfin Tuna | 0.354 | High | No (limit) |
| Bigeye Tuna | 0.689 | Very High | No (limit/avoid) |
| King Mackerel | 0.730 | Very High | No (limit/avoid) |
| Swordfish | 0.995 | Very High | No (limit/avoid) |
How to Make Safer Sushi Choices
Making informed choices doesn't mean giving up sushi. Instead, it means being strategic about your selection. Here are some tips for a safer dining experience:
- Embrace Vegetarian Options: Sushi doesn't have to contain fish. Opt for rolls with ingredients like avocado, cucumber, mushrooms, or sweet potato, which are all mercury-free.
- Vary Your Fish: Don't stick to just one or two types. Eating a variety of fish and shellfish helps dilute your overall mercury intake.
- Know Your Tuna: If you eat tuna, understand the difference. Bigeye and bluefin are high in mercury, while canned light tuna is lower, though less common for sushi. Ask your server which type is used, if possible.
- Consider Farmed vs. Wild: Some studies indicate that farmed salmon has lower mercury levels than wild salmon. Choosing reputable, sustainably farmed sources can be a good strategy.
- Check FDA Guidelines: For pregnant women, nursing mothers, and young children, the FDA and EPA offer specific advice on limiting high-mercury fish while encouraging the consumption of low-mercury varieties. Always follow these guidelines for the most vulnerable populations. You can learn more directly from the FDA advice about eating fish.
Conclusion
While mercury in seafood is a valid concern, it should not be a reason to avoid sushi altogether. The key is to know which sushi has the lowest mercury and make smart, balanced choices. By favoring smaller, low-mercury options like salmon, shrimp, and scallops, and limiting larger, predatory fish like tuna and swordfish, you can safely enjoy the health benefits of seafood, including its high protein and omega-3 fatty acids. Opting for vegetarian rolls or diversifying your fish choices further enhances your food safety. An informed palate is a healthy palate, ensuring your next sushi meal is both delicious and safe.
