Understanding Mercury in Tuna
Mercury is a naturally occurring element that can accumulate in fish, particularly as methylmercury, a potent neurotoxin. Larger, longer-lived predatory fish tend to accumulate higher concentrations of mercury over their lifespan. This is the primary reason why mercury levels differ significantly between various types of tuna and other seafood. Environmental factors, including industrial emissions, also contribute to the amount of mercury in the marine ecosystem.
Species: The Main Factor for Mercury Content
The species of tuna is the single most important indicator of its mercury content. The two most common types found in canned products are skipjack and albacore.
- Skipjack (Chunk Light) Tuna: This is a smaller, faster-growing species. As a result, it accumulates less mercury during its shorter lifespan compared to larger tuna. Canned chunk light tuna, which is typically made from skipjack, is consistently the lowest mercury option on the market.
- Albacore (Solid White) Tuna: This species is larger and lives longer than skipjack, leading to higher mercury concentrations. The mercury levels in albacore tuna can be up to twice as high as those found in chunk light tuna.
- Other Species: Species like bigeye and yellowfin tuna, often sold as fresh or frozen steaks, contain even higher levels of mercury and are recommended to be consumed less frequently or avoided entirely by sensitive groups.
Leading Brands and Their Mercury Levels
When choosing a brand, it's not just the species that matters, but also the company's sourcing and testing practices. Some brands go the extra mile to ensure their products have the lowest possible mercury levels.
Safe Catch
Safe Catch is the only brand that claims to test every single tuna for mercury before processing, setting a strict limit that is 10 times lower than the FDA's action limit for their Elite Wild Tuna. This makes their Elite Wild Tuna one of the most consistently low-mercury options available, and the American Pregnancy Association recommends it. While Consumer Reports found that Safe Catch's mercury levels were low, they noted that other light tuna brands were also low and more affordable.
Wild Planet
Wild Planet sources smaller, younger tuna caught with pole-and-line or troll methods, which naturally results in lower mercury levels. The brand conducts annual third-party testing to verify its low mercury average. However, it is important to note that a Consumer Reports test found some samples of Wild Planet's skipjack had surprisingly high mercury levels, putting them closer to albacore in certain instances. This highlights the potential for variation even in brands with good practices.
Conventional Brands (Bumble Bee, Chicken of the Sea, StarKist)
Major brands like Bumble Bee, Chicken of the Sea, and StarKist offer canned light tuna made from skipjack, which is generally a low-mercury choice. Consumer Reports testing has shown that the chunk light versions of these brands can have low mercury levels, comparable to Safe Catch's offerings. However, their albacore products can have significantly higher mercury content, sometimes warranting very limited consumption.
Comparison of Low Mercury Tuna Options
| Feature | Safe Catch Elite Wild Tuna | Wild Planet Skipjack | Conventional Chunk Light | Conventional Albacore |
|---|---|---|---|---|
| Species | Skipjack | Skipjack | Skipjack | Albacore |
| Mercury Testing | Tests every fish; 10x stricter than FDA limit for Elite | Annual third-party testing | Varies by manufacturer, less frequent testing | Varies by manufacturer |
| Average Mercury | Very low (guaranteed below 0.1ppm) | Low average (0.067ppm) | Low, but variable | High, often much higher than light tuna |
| Sourcing Method | Sustainable, wild-caught | Pole & Line, Troll caught | Varies, often less sustainable | Varies, can be long-line |
| Cost | Premium price | Mid-range price | Affordable | Mid-range price |
| Risk of High Mercury | Extremely low due to individual testing | Low average, but possible spikes | Generally low, but potential for variance | High risk due to species |
Tips for Choosing Low-Mercury Tuna
- Prioritize Skipjack: Always opt for canned chunk light or skipjack tuna over albacore for the lowest mercury levels.
- Check the Label: Some higher-quality brands, like Safe Catch, specifically state their mercury testing protocols or limits on the packaging.
- Consider Sustainable Fishing Methods: Brands that use pole-and-line or troll-caught methods often target younger, smaller fish with lower mercury content, as noted by Wild Planet.
- Eat in Moderation: No matter the brand, it's wise to eat tuna in moderation. The FDA and EPA provide guidelines for seafood consumption to manage mercury intake.
- Explore Alternatives: If you're highly concerned about mercury, consider other low-mercury seafood like sardines, salmon, or anchovies.
Conclusion
While Safe Catch provides the greatest assurance of low mercury levels due to its unique individual testing process, other brands' skipjack or chunk light tuna varieties are also a safe and affordable choice for most people. The most significant factor influencing mercury content is the species of tuna, with smaller skipjack containing less mercury than larger albacore. Consumers who are particularly sensitive, such as pregnant women and children, should opt for brands with verified testing and choose skipjack to minimize risk. By understanding the factors that influence mercury levels and making informed choices, you can continue to enjoy the nutritional benefits of tuna responsibly. For more detailed testing information, refer to independent research from organizations like Consumer Reports.
