The High-Mercury Sushi List
Certain types of fish, particularly larger, longer-lived predatory species, are known to accumulate significant amounts of mercury through a process called biomagnification. When ordering sushi, it's wise to limit or avoid varieties containing the following fish to reduce your mercury intake:
- Bigeye Tuna (Maguro/Toro): Prized for its fatty cut (toro), bigeye tuna is a top predator and consistently ranks high in mercury levels. Bluefin tuna also falls into this high-mercury category.
- Swordfish (Kajiki): As a large, apex predator, swordfish accumulates high concentrations of methylmercury, making it a fish that is generally recommended to avoid.
- King Mackerel (Sawara): Not to be confused with Atlantic mackerel, king mackerel is a larger fish known to contain high levels of mercury and should be consumed sparingly, if at all.
- Marlin (Makjiki): Blue marlin is a large game fish that is sometimes used for sushi and contains a high amount of mercury.
- Tilefish (Gulf of Mexico): The FDA identifies tilefish from the Gulf of Mexico as having some of the highest mercury levels.
Safer, Low-Mercury Sushi Options
Fortunately, there are many delicious and nutritious low-mercury options available at most sushi restaurants. These are typically smaller fish or shellfish lower on the food chain, meaning they have less opportunity to accumulate significant mercury levels.
- Salmon (Sake): Both wild-caught and farmed salmon are excellent low-mercury choices rich in omega-3 fatty acids.
- Freshwater Eel (Unagi) and Conger Eel (Anago): These eels are generally considered low in mercury and are often cooked and served with a sweet sauce.
- Shrimp (Ebi): A very low-mercury option, shrimp is a staple in many cooked sushi rolls.
- Crab (Kani): Both real and imitation crab meat are safe, low-mercury choices.
- Scallops (Hotategai): This shellfish has a very low mercury concentration.
- Squid (Ika) and Octopus (Tako): Both squid and octopus contain low levels of mercury.
- Sea Urchin Roe (Uni): A decadent and low-mercury delicacy.
- Clams, Oysters, and other Shellfish: Generally safe, with very low mercury levels.
High Mercury vs. Low Mercury Sushi Fish Comparison
| Fish Type (Sushi Name) | Typical Mercury Level | High Mercury Risk? | Notes |
|---|---|---|---|
| Bigeye/Bluefin Tuna (Maguro/Toro) | High | Yes | A large predator that bioaccumulates significant mercury. |
| Swordfish (Kajiki) | High | Yes | A very large, long-lived predatory fish. |
| King Mackerel (Sawara) | High | Yes | A large, predatory fish with high mercury levels. |
| Salmon (Sake) | Very Low | No | A good source of omega-3s with minimal mercury risk. |
| Eel (Unagi/Anago) | Very Low | No | Often served cooked; a safe, low-mercury option. |
| Shrimp (Ebi) | Very Low | No | Excellent for cooked rolls and very low in mercury. |
| Scallops (Hotategai) | Very Low | No | A shellfish with one of the lowest mercury concentrations. |
| Yellowfin Tuna (Ahi) | Moderate | Moderate | Lower than Bigeye, but still contains moderate mercury levels; limit consumption. |
Why Mercury Accumulates in Certain Fish
The accumulation of methylmercury, the organic form of mercury most dangerous to humans, is a direct result of a process called biomagnification. This process starts with industrial and natural sources releasing mercury into the environment. Microorganisms in water bodies convert this mercury into methylmercury, which is then absorbed by small aquatic organisms like algae and plankton.
This is where the food chain effect comes into play. Small fish eat the plankton, absorbing the methylmercury. As larger fish prey on these smaller fish, the concentration of mercury increases in their bodies. The largest, oldest predatory fish, such as bluefin tuna and swordfish, sit at the top of this chain, accumulating the highest levels of mercury over their long lifespans. It's a key reason why consuming smaller, shorter-lived fish is a safer choice.
How to Reduce Your Mercury Exposure
Enjoying sushi while being mindful of mercury is entirely possible by making informed choices. Here are some actionable tips:
- Vary Your Fish Intake: Don't rely solely on tuna. Explore other options like salmon, eel, crab, and shrimp to lower your overall mercury exposure over time.
- Order Lower-Mercury Species: Actively choose sushi rolls and sashimi made with fish known to have low mercury content. For example, opt for a salmon roll instead of a spicy tuna roll.
- Be Mindful of Frequency: If you enjoy high-mercury fish like tuna, treat it as an occasional delicacy rather than a daily or weekly staple. The FDA provides guidelines for consumption limits, especially for sensitive groups.
- Ask Questions: If you frequent a specific sushi restaurant, ask your server about the type of tuna or fish they source. Some restaurants may be transparent about their sourcing practices.
- Explore Vegetarian and Cooked Rolls: Many delicious rolls are made with vegetables, cooked fish, or other ingredients like avocado, cucumber, and cooked shrimp, which pose no mercury risk.
Conclusion: Balancing Your Enjoyment with Health
Enjoying sushi doesn't have to mean compromising your health. While some popular options like bigeye tuna carry a high risk of mercury exposure, a wide array of lower-mercury alternatives exists. By being aware of which sushi is high in mercury and making conscious choices, you can enjoy this culinary tradition safely. Prioritizing smaller, non-predatory fish and varying your choices is the best way to indulge without overexposure to mercury's potential health effects. For more health-related dietary advice, it's always wise to consult official guidelines, such as those from the FDA.
