Understanding Mercury in Tuna
Mercury is a naturally occurring element that, when converted to methylmercury by ocean bacteria, can be absorbed by marine life. Larger, older predatory fish, like bigeye and albacore tuna, accumulate higher concentrations of mercury throughout their lifespan through a process called bioaccumulation. Regular exposure to high levels of mercury can have adverse effects on the brain and nervous system, and poses particular risks for sensitive populations such as pregnant women, nursing mothers, and young children.
For this reason, consumers must be discerning when choosing canned tuna. While the FDA sets a safety standard for mercury in fish, individual cans can sometimes have unpredictably higher levels. This variation makes brand transparency and consistent testing crucial for making the safest choice.
Key Factors for Selecting Low-Mercury Tuna
When evaluating tuna brands, consider these primary factors that influence mercury levels:
- Tuna Species: The type of tuna is the most important indicator of mercury content. Skipjack, which is typically labeled as 'canned light' tuna, contains significantly less mercury than larger species like albacore ('white') tuna. Bigeye tuna, often used in sushi, has the highest mercury levels and should be avoided by vulnerable groups.
- Size and Age of Fish: Smaller, younger tuna accumulate less mercury over their shorter lifespan. Sustainable fishing methods like pole-and-line or troll-caught techniques typically target these smaller, migratory fish, leading to a naturally lower mercury concentration.
- Testing and Processing: Some brands go above and beyond standard protocols by testing every single fish they process. This meticulous approach significantly reduces the risk of consuming a can with an unusually high mercury spike. The packing method also matters, as some brands pack raw fish and cook it once, preserving natural juices and omega-3s, while others pre-cook and add fillers.
Top Brands with Low Mercury Standards
Some brands are more transparent and proactive about managing mercury levels than others. Here are some of the leaders in the low-mercury tuna market:
- Safe Catch: This is the only brand that tests every single tuna for mercury using proprietary technology. Their Elite Wild Tuna is tested to a limit 10 times stricter than the FDA's standard for safety. For this reason, Safe Catch Elite is the official tuna of the American Pregnancy Association.
- Wild Planet: This brand specializes in smaller, pole-and-line caught fish. Their third-party testing verifies that their skipjack tuna's average mercury content is 14 times lower than the FDA's limit. However, Consumer Reports noted some can-to-can variability in Wild Planet's skipjack in one test, emphasizing the value of their average numbers over individual can purity.
- Traditional Brands (Light Tuna): Standard supermarket brands like Bumble Bee, StarKist, and Chicken of the Sea offer chunk light tuna, which is typically skipjack and generally lower in mercury than their albacore counterparts. While they don't test every fish, opting for their light tuna over white is a safer bet for moderate consumption for non-sensitive individuals.
Comparison of Low-Mercury Tuna Options
| Brand | Species | Key Mercury Fact | Catch Method | Primary Benefit |
|---|---|---|---|---|
| Safe Catch Elite | Skipjack | Every fish tested to 10x stricter than FDA limit | FAD-free Purse Seine | Guaranteed lowest mercury of any brand |
| Wild Planet Skipjack | Skipjack | Averages 14x lower mercury than FDA limit based on annual tests | Pole & Line / Troll | Smaller, younger fish naturally lower in mercury |
| Traditional Chunk Light | Skipjack | Average mercury significantly lower than Albacore | Various (often Purse Seine) | Affordable and widely available low-mercury option |
| Safe Catch Albacore | Albacore | Every fish tested to 2.5x stricter than FDA limit | Pole & Line / Troll | Lower mercury for albacore, but higher than their skipjack |
Safe Consumption Recommendations
The FDA and EPA offer guidance on seafood consumption to balance nutritional benefits with mercury exposure risks, with specific advice for vulnerable populations.
- General Adults: Can safely consume 2–3 servings of low-mercury fish, including canned light tuna, per week. Limit albacore to one 4-ounce serving per week.
- Pregnant/Nursing Women & Young Children: Should be highly cautious. Some sources recommend avoiding tuna altogether due to the risk of can-to-can mercury spikes, although some light tuna is considered safer in moderation. Sticking to 1-2 servings per week of low-mercury, tested options like Safe Catch Elite is the most conservative approach.
Beyond Tuna: Other Low-Mercury Seafood Options
Diversifying your seafood intake can provide the benefits of omega-3s and other nutrients while further minimizing mercury exposure. Excellent low-mercury alternatives include:
- Canned salmon (wild-caught Alaskan pink or sockeye)
- Sardines
- Anchovies
- Trout
- Oysters and scallops
Conclusion
While Safe Catch offers the highest degree of confidence with its individual fish testing and guaranteed lowest mercury content, opting for any brand's skipjack tuna (labeled 'canned light') is a generally reliable and affordable way to reduce mercury intake compared to albacore. To make the safest choice, prioritize brands that are transparent about their testing methods and source smaller, younger fish caught sustainably. By staying informed about the species and practices behind your seafood, you can confidently enjoy the nutritional benefits of tuna while minimizing mercury risks. For detailed sustainability information on various seafood, including tuna, consider consulting resources like the Monterey Bay Aquarium's Seafood Watch guide.
